# Physics discussion: FTL drives, Speed of Light, Life in the Universe, etc



## Serendipity (Jul 16, 2017)

If the human race does not kill itself with stupidity, faster than light travel will happen in some form or another.... still have headaches about the real implications of that...


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## Vertigo (Jul 16, 2017)

Serendipity said:


> If the human race does not kill itself with stupidity, faster than light travel will happen in some form or another.... still have headaches about the real implications of that...


????? How do you figure that?


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## Serendipity (Jul 17, 2017)

Vertigo said:


> ????? How do you figure that?


Apart from the work on Alcubierre's Drive and Quantum Entanglement you mean?


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## Vertigo (Jul 17, 2017)

Quantum entanglement is not travel, though FTL data communications using it may be possible, and the Alcubierre drive is still only a speculative and unproven concept, really no more likely than wormholes or even hyperspace. I still think the strongest explanation of the Fermi paradox is that FTL travel is simply not possible. (Sadly... believe me I'd love for it to be possible )

The problem with quantum entanglement for communication is that you need to have entangled particles at each end of the communication 'channel' but they must be created together, therefore after creation one must be transported to the other location and that can only be done at a maximum of light speed. So to use quantum entanglement to communicate between two points say 10 light years apart you must first wait ten years whilst the entangled particles are sent from one point to the other. Then in order to have meaningful communication you need at least millions of such particles.

ETA: Charles Stross deals with this entanglement problem quite neatly in Singularity sky where your supply of entangled particles for communication is finite and, like a battery, is useless once used up until you can get more entangled particles.


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## Mirannan (Jul 17, 2017)

Vertigo said:


> Quantum entanglement is not travel, though FTL data communications using it may be possible, and the Alcubierre drive is still only a speculative and unproven concept, really no more likely than wormholes or even hyperspace. I still think the strongest explanation of the Fermi paradox is that FTL travel is simply not possible. (Sadly... believe me I'd love for it to be possible )
> 
> The problem with quantum entanglement for communication is that you need to have entangled particles at each end of the communication 'channel' but they must be created together, therefore after creation one must be transported to the other location and that can only be done at a maximum of light speed. So to use quantum entanglement to communicate between two points say 10 light years apart you must first wait ten years whilst the entangled particles are sent from one point to the other. Then in order to have meaningful communication you need at least millions of such particles.
> 
> ETA: Charles Stross deals with this entanglement problem quite neatly in Singularity sky where your supply of entangled particles for communication is finite and, like a battery, is useless once used up until you can get more entangled particles.



I don't think that lack of FTL is a viable explanation for the Paradox. Someone said it well: "Looking for evidence of technological activity in an inhabited Galaxy ought to be like looking for such evidence on Manhattan Island".

Without FTL, an expanding civilisation would be more or less forced to use as much as possible of the resources of a single solar system -which leads to the formation of a Dyson swarm quite quickly. (Certainly compared to the lifetimes of stars!)

The signature of such a swarm would be an object with the luminosity of Sol (approximately) but with a spectrum roughly corresponding to a blackbody at a temperature of around 300K, if the people are anything like us, perhaps with occasional weak flashes of visible light. (From gaps in the shell.) I'm not aware that anyone has ever looked for those.


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## SilentRoamer (Jul 17, 2017)

Serendipity said:


> If the human race does not kill itself with stupidity, faster than light travel will happen in some form or another.... still have headaches about the real implications of that...



Not sure why you would think this...



Serendipity said:


> Apart from the work on Alcubierre's Drive and Quantum Entanglement you mean?



Sorry what "work" on an Alcubierre drive are you talking about? This is a purely theoretical mode of travel, it talks about the contraction of spacetime ahead of the object and expansion of spacetime behind it and hasn't had serious scrutiny or revision for a while, whilst all sounding very good it is completely theoretical and hinges on properties of spacetime we are not even sure exist.  

With Quantum Entanglement - nothing actually goes FTL, the information is already present in the photon just a measured state does not exist. Nothing is physically transported.

Whilst I agree that progress marches ever on there are certain principles in physics which we expect to hold true. The speed of light to all observers is one of these things, if the speed of light were to be surpassed then it has all sorts of implications for our understanding (or lack thereof) of known science. 

Theoretically an Einstein-Rosen bridge has the ability to "allow" ftl travel through remotely connected regions of space, along with CTC's and other postulated theoretical spacetime metrics - although they are only theoretical.

Unfortunately I think we are approaching the Golden Age of humanity - we may already be there right now.


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## Serendipity (Jul 19, 2017)

OK - several points to reply to here - so bear with me....


Alcubierre's Drive - further work was done beyond the original paper, which started to identify how to take the theoretical to reality. All I remember is it was done in this century. Although there is a long way to go, we have already taken a step in the right direction. I would over time expect even more work to be done on the road to making this a reality - if other methods etc don't get there first.
Quantum Entanglement - yes, at the moment, you would need to have quantum entangled particles travel sub light speed before they can be used. However, once set up correctly, a thing or person or alien could use the quantum entangled particles to move data from one place to another. To the newly come user this would appear to be travelling faster then light. It all boils down to relativity - sorry couldn't resist that pun. A good novel that describes this as best as s/he knew it at the time was Greg Egan's Child's Ladder.
The final point is perhaps going to the most controversial. The homo sapiens has at the most been around for 1.8 million years, though could have developed any time up to 200,000 years ago. Now let's start stacking up the probabilities of the human race having been able to survive global disasters since then e.g. surviving the nuclear race, worldwide killer virus epidemic etc etc. Bottom line is either the human race has been very lucky or it has had some kind of guidance to survive. Ramifications of either situation I'm going to leave to your all too vivid imaginations, except for one point - faster than light travel does allow you to go back in time - and this is where my brain hurts...


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## SilentRoamer (Jul 20, 2017)

Serendipity said:


> OK - several points to reply to here - so bear with me....
> 
> 1. Alcubierre's Drive - further work was done beyond the original paper, which started to identify how to take the theoretical to reality. All I remember is it was done in this century. Although there is a long way to go, we have already taken a step in the right direction. I would over time expect even more work to be done on the road to making this a reality - if other methods etc don't get there first.



I will always bear with you - even if I may respectfully disagree. I believe we can have these differences of opinion and still be measured and civil! 

Ok so The Alcubierre drive - the problem I have is that we have to compare apples and oranges when looking at this compared to the existing fruit of human labour and the reason I say this: although our understanding of physics has changed over the centuries and decades it is as complete as it has ever been. The Alcubierre drive isn't based in the realm of scientific plausability because it does a number of things:

1. It assumes a number of intrinsic properties of spacetime (note we need to use the word spacetime here as the method of compression must deal with einsteinian and not newtonian understandings of the interconnected nature of spacetime, namely that time and space are not discreet.) 
2. It assumes an ability to somehow "control" spacetime at a fundamental level. 

Now obviously we can only look at this from the perception of modern man - no doubt an ancient human would balk at the notion of flying metal. However we do have the best understanding of physics we have ever had and the invariable speed of light is a constant that appears to hold true over the entirety of the Observable Universe. Laws of isotropy and homogeneity dictate this is the most likely state of the remainder of the unobservable U, whether finite and bounded and infinite and unbounded. 



Serendipity said:


> 2. Quantum Entanglement - yes, at the moment, you would need to have quantum entangled particles travel sub light speed before they can be used. However, once set up correctly, a thing or person or alien could use the quantum entangled particles to move data from one place to another. To the newly come user this would appear to be travelling faster then light. It all boils down to relativity - sorry couldn't resist that pun. A good novel that describes this as best as s/he knew it at the time was Greg Egan's Child's Ladder.



Ok I think you understand Entanglement but your terminology is a bit confusing. You talk about "moving" data but nothing is ever actually moved. Another problem - the most fundamental problem, is that Entanglement is random until observation. It's like me sending you a box, and keeping a box myself, I know whatever is in my box is also in your box, fantastic! Except I don't know what's in my box until I measure it and I have no way of controlling the result of the measurement. As I have argued - this has more applications for secure communications than it does for instant data transfer, especially as anything on geological scales is minuscule compared to the speed of light. 

FTL does allow time travel you are totally right! So many people fail to accept this but it is mathematically unassailable. 

Interesting discussion.


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## Ursa major (Jul 20, 2017)

Serendipity said:


> yes, at the moment, you would need to have quantum entangled particles travel sub light speed


Not in the case of photons, as far as I can _c_....


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## Serendipity (Jul 21, 2017)

Ursa major said:


> Not in the case of photons, as far as I can _c_....


Oh groan.... but you're right... but we're still limited to the speed of light.


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## Serendipity (Jul 21, 2017)

SilentRoamer said:


> I will always bear with you - even if I may respectfully disagree. I believe we can have these differences of opinion and still be measured and civil!
> 
> Ok so The Alcubierre drive - the problem I have is that we have to compare apples and oranges when looking at this compared to the existing fruit of human labour and the reason I say this: although our understanding of physics has changed over the centuries and decades it is as complete as it has ever been. The Alcubierre drive isn't based in the realm of scientific plausability because it does a number of things:
> 
> ...



1. I'm always happy to join in a healthy constructive debate...  After all that's how a lot of scientific progress ends up being made.

2. Alcubierre's Drive - I remembered correctly that there has been further work done since the initial paper came out in 1994. It involves changing the warp bubble into a warp ring. This was being worked on by NASA in 2012, but I haven't seen any reports since then. I believe they were setting up an experiment to see if they could measure the warpedness (is there such a word?) of the Alcubierre metric - part of the theory behind the drive. (The fact that we have not seen any results published means nothing - the Americans sometimes classify promising results for national security reasons - I'm not saying this is the case here - we just don't know.)

3. Quantum Entanglement - the principles you describe are correct in essence. However, there is a mechanism of effectively having the same type of event occur instantaneously at the same time at a distance. I would argue that there should be a way to engineer getting composite signals across that same space, particularly when you consider that communications engineers have already developed a large cadre of signal analysis and correction methods, which I believe would help in such a situation.

4. Agreed faster than light travel could lead to time travel - which is why this does my brain in!


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## SilentRoamer (Jul 21, 2017)

Hey Serendipity,

In Quantum Entanglement there is no "event" or physical change, merely a measurement of an existing physical state - one which we can't set beforehand. So my analogy holds true - we don't know what the measurement is until we make it, the nature of making the measurement forces the state - the particle at the other end always had the same state - it just wasn't measured! Spooky action at a distance!

Ok with regards to the Alcubierre drive - my original criticism still stands. The Alcubierre "drive" is an idea based on solutions to Einsteins field equations, the solutions are mathematically consistent BUT in order for them to work they need a form of negative matter - now this is a form of exotic matter that we don't even know exists, indeed we don't know if it is even possible for this matter to exist. Lets just say that this matter does exist - it doesn't preclude a physical mechanism that can deliver on the solutions to the field equations. The solutions also ignore QUANTUM properties - which is a given granting that Quantum and Standard physics aren't unified. So it may be that once more work is done unifying Gravity with QE that the solutions then become unworkable. 

Phew - that was fun


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## Cathbad (Jul 21, 2017)

I'm no longer convinced we're limited to the Speed of Light.  Wasn't it just a few years ago they discovered  particle that moved at _near_ light speed (thinking at first it had went faster than)?  And now they've taken a step toward teleportation.

Seems to me, given enough time, man has shown he can do virtually anything.


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## Vertigo (Jul 21, 2017)

The one thing we can never do though is break the rules of physics. Of course we don't yet know all the rules of physics but ultimately if the speed of light is proven to be a physical limit then, no matter how much time we have or how clever we are we can never do the impossible.

Don't be misled by that teleportation word being used. Quantum teleportation bears no resemblance to anything we would normally call teleportation. In other words we have not taken any steps towards teleporting a physical object from one place to another. I think it's really irritating that the scientist are using the word teleportation in this context.


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## Cathbad (Jul 21, 2017)

Vertigo said:


> Don't be misled by that teleportation word being used.



Oh, I agree.  But I do think it is a step in the direction of.


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## Mirannan (Jul 21, 2017)

Further to all this, Harold White of NASA has been working on a modified warp drive that brings down the mass requirement substantially (putting it mildly!) from about the mass of Jupiter to a tonne or so. In fact, preliminary experiments are already being done. Yes, warp field experiments being done _right now_.

As if that wan't enough, the same group is also working on a reactionless drive using quantum vacuum energy. Link: Quantum vacuum thruster


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## SilentRoamer (Jul 21, 2017)

Cathbad said:


> I'm no longer convinced we're limited to the Speed of Light.  Wasn't it just a few years ago they discovered  particle that moved at _near_ light speed (thinking at first it had went faster than)?  And now they've taken a step toward teleportation.
> 
> Seems to me, given enough time, man has shown he can do virtually anything.



Light speed isn't just some arbitrary speed though, the constant C is found in lots and lots of physics. It is a physical constraint and the limit at which information can be exchanged. Anything sub-light, even if it is near lightspeed is still sub light. In theory you can accelerate something to 99.99 C, but the energy requirements to make something physical move at C are infinite. So near lightspeed is absolutely within the realm of physics.

I also believe intellect can accomplish anything, anything within the realm of physics and I suspect physical laws (at least some) to be inviolate. An example of this for me is the Second Law of Thermodynamics.  

@Mirannan I find the idea of a Quantum thruster very appealing for future space travel. The warp drive still depends on matter we don't even know exists, so bringing the energy requirement down is irrelevant if we can't produce negative mass exotic matter.


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## Cathbad (Jul 21, 2017)

There was no way we could fly - according to the physics of the time.

There was no way an iron ship could float - according to the physics of the time.

Every generation seems to have believed their knowledge of physics was the end-all-get-all... the Final Word.

And apparently, we're still just as arrogant.


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## Vertigo (Jul 21, 2017)

I'm not sure that is quite accurate I think all lot of uneducated people might have said those things at one time but I'm not too sure all that many scientists did; da Vinci certainly believed we could do the former and Archimedes pretty much proved the latter. Science back then had a lot of ideas that hadn't been subjected to the scientific method (because that hadn't really been formulated) and so a lot of their ideas were never more than unproven theories. Our current set of theories make many predictions which so far are proving very robust, sufficiently so to believe they are at least getting close to the truth. I don't think any scientists are so arrogant as to believe we have reached the final truth but each iteration is getting closer. It is theoretically possible that a completely new branch of physics might yet come along and turn everything completely on it's head but I think it unlikely that anything as fundamental as the speed of light in vacuum is going to be overturned, there are just so many tested predictions that are based on it. As @SilentRoamer so neatly stated above: "we do have the best understanding of physics we have ever had and the invariable speed of light is a constant that appears to hold true over the entirety of the Observable Universe." I don't think this is arrogance but just pragmatism based on observation.

It's a bit like Moore's Law which, of course is not a law and has more recently been 'failing'. Eventually we start hitting physical limits and we can't keep gong faster, smaller etc. for ever.

But of course we cannot predict the future. I just think the weight of probability is massively against it.


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## Cathbad (Jul 21, 2017)

da Vinci was an artist, not a physicist.

An artist's mind is often more accepting of possibilities than most scientists. And they - including writers - have been the very reasons for science stretching its boundaries.

And... are you sure "pragmatism" isn't just an excuse for "arrogance"?

Just askin...

At 60, I can honestly say that I have learned that "Absolutes" are bound to change.


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## Ursa major (Jul 21, 2017)

We seem to be relatively confident (rightly or wrongly) about what is possible _within_ space, but still have little or no idea what that space is. Until we can grasp what it is**, we can't really say what is possible and what is not if we could have some sort of access to whatever it is that space is.


** - One of the possibilities -- the idea that what we experience (including ourselves) within the volume of space is a projection from a surface surrounding that volume -- really baffles me, even at the simplest level (which is beyond what my brain can manage). For instance: are distances within that volume necessarily going to be the same as linear distances on that surface (whose physical characteristics are completely unknown to us, if only because we're not sure that surface exists at all)?


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## Brian G Turner (Jul 21, 2017)

We're kind of off-topic here from a possible Planet 10 here, and into an interesting subject in it's own right.

What stands out for me on that is that Newtonian physics was, for its time, a very good description of the universe as we perceived it then - with a few clear problems.

However, Einstein's theories are little different nowadays. There remains the issue of Relativity being unable to account for the motion of stars in a galaxy, for example. Every time we read/hear about "dark matter" or "dark energy" we are basically discussing the failure of Relativity to describe the observable universe, and underlining how incomplete our understanding of physics still is.

So holding on to C as an upper limit, just because a theory we know must be in error or incomplete says so? I wouldn't put good money on holding to that.


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## Cathbad (Jul 21, 2017)

And, something I've often made fun of... How can we draw a straight line on a spherical planet??


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## Ursa major (Jul 21, 2017)

Setting aside that planets don't tend to be truly spherical (the Earth is a lumpy geoid, not a sphere, although that doesn't really tell us much)....


A "straight line" on the surface of the Earth between two points is a portion of the great circle that passes through both those points.


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## Dave (Jul 21, 2017)

Brian G Turner said:


> We are basically discussing the failure of Relativity to describe the observable universe, and underlining how incomplete our understanding of physics still is.
> 
> So holding on to C as an upper limit, just because a theory we know must be in error or incomplete says so? I wouldn't put good money on holding to that.





			
				Hamlet Act 1 said:
			
		

> There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy.



If I could predict the future...  then I would put good money on it. Unfortunately, I can't.

Great discussion, in any case. Pity it is so off topic.


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## Vertigo (Jul 22, 2017)

Still off topic but no one seems to be complaining!

If the scientists were to say that it is absolutely impossible to travel faster than the speed of light and that it can never happen then I agree it would be arrogance. But they and we aren't, or at least most aren't, what they and we are saying is that on the basis of the current evidence it is very unlikely, which I don't think is arrogance. However to say that because we have achieved so much we can achieve anything including exceeding the speed of light is equally arrogant and, in my view, is based on less evidence than the contrary argument. Remember, the initial statement that fired the discussion was the assumption that we would exceed the speed of light and achieve teleportation, and that very soon.

For me (and here I risk going even further off topic) it's like the assumption that just because there are trillions of star systems out there and there is life here there *must* be other life out there. This is an equally flawed assumption; we so far have found life in just one place Earth and although life is pretty much everywhere on Earth all the evidence points to a 'tree of life' reducing back in the far past to a single genesis as the DNA indicates that all life on Earth is related. So far we have found no other life elsewhere; none. So, with only a single instance, no probability can be calculated it doesn't matter whether there are ten, ten thousand, ten million or ten trillion other planets out there the probability does not change unless and until a second instance of life is found. Anything else is faith not science. If we find another instance of life then the probability immediately shifts to it being highly likely there is lots of life out there but whilst we have only one instance no such assumption can be made.

I make no absolute assumptions but I do consider the weight of evidence to point to certain conclusions being far more likely than others.


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## mosaix (Jul 22, 2017)

If I remember correctly I have read, and maybe quoted it here on Chrons elswhere, it isn't that travelling faster than the speed of light that is impossible but breaking through the barrier of light speed.

Again, if I remember correctly, there are/were particles that travelled faster than light shortly after the Big Bang and before the current laws of physics were established - I think that's right. Hope so.


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## Mirannan (Jul 22, 2017)

I think it's worth mentioning that the definition of "travelling" may well be the issue here. Current warp drive theories, and the theoretical idea of a wormhole jump, don't have the ship doing the "travelling" moving faster than light - at least, locally to the ship. What is happening is that space itself is being warped in such a manner that, from outside, the ship appears to be travelling faster than light.

There is another example of this. It is almost certain that there are objects beyond our visual horizon (because they are further away in lightyears than the number of years since the Big Bang) that "appear" to be travelling faster than light away from us. But what is actually happening is that the space between here and there is expanding faster than light can travel.

A similar situation is thought to have existed during the cosmic inflation era; in that case, it was throughout space.


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## Vertigo (Jul 22, 2017)

Mirannan said:


> I think it's worth mentioning that the definition of "travelling" may well be the issue here. Current warp drive theories, and the theoretical idea of a wormhole jump, don't have the ship doing the "travelling" moving faster than light - at least, locally to the ship. What is happening is that space itself is being warped in such a manner that, from outside, the ship appears to be travelling faster than light.
> 
> There is another example of this. It is almost certain that there are objects beyond our visual horizon (because they are further away in lightyears than the number of years since the Big Bang) that "appear" to be travelling faster than light away from us. But what is actually happening is that the space between here and there is expanding faster than light can travel.
> 
> A similar situation is thought to have existed during the cosmic inflation era; in that case, it was throughout space.


And if my dust encrusted physics is correct that doesn't cause causality issues as no information is or can be passed in this way since nothing is actually 'travelling' it's just that the distance between us is increasing as the space expands.


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## Parson (Jul 22, 2017)

Vertigo said:


> And if my dust encrusted physics is correct that doesn't cause causality issues as no information is or can be passed in this way since nothing is actually 'travelling' it's just that the distance between us is increasing as the space expands.


Is that a potential answer to the question of the "speed" of gravity?


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## Vertigo (Jul 22, 2017)

Hmm... not sure. I did see something recently about gravity waves that seemed quite positive that they travel at the speed of light (despite Weber! ) I remember thinking 'that's interesting' when I read it. But, for the life of me, I can't remember where I saw it just that it was an interesting red herring when I was looking for something else.


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## Brian G Turner (Jul 22, 2017)

Vertigo said:


> For me (and here I risk going even further off topic) it's like the assumption that just because there are trillions of star systems out there and there is life here there *must* be other life out there.



If life arose here because of natural processes - no matter how common or rare - then it must be presumed to take place elsewhere. This is especially when we are continually surprised by the diversity life on our own planet, and the fact we haven't even begun properly exploring our own star system. 
The alternative is surely that life is a miracle and therefore works outside the laws of physics?



Mirannan said:


> the definition of "travelling" may well be the issue here.



That's a really good point - worm holes have long been suggested as a way to tunnel through the fabric of space-time and give the illusion of having travelled faster than light, without actually violating that principle. I suspect the jump gates in Babylon 5 worked on that.



Mirannan said:


> A similar situation is thought to have existed during the cosmic inflation era; in that case, it was throughout space.



That's another seriously interesting point - we've discussed studies here before now that suggest that universal constants in physics might be neither universal, nor constant. 

In this example, the value of C might be different in different areas of the universe (and in time), according to context. I can't recall anything specific to C (though on a side note, the speed of light does vary according to the medium it passes through. As a constant, the value of C is defined as through a vacuum, but vacuums themselves can be seriously interesting for the fact that they aren't!).


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## Dave (Jul 22, 2017)

Vertigo said:


> We so far have found life in just one place Earth and although life is pretty much everywhere on Earth all the evidence points to a 'tree of life' reducing back in the far past to a single genesis as the DNA indicates that all life on Earth is related. So far we have found no other life elsewhere; none. So, with only a single instance, no probability can be calculated it doesn't matter whether there are ten, ten thousand, ten million or ten trillion other planets out there the probability does not change unless and until a second instance of life is found. Anything else is faith not science. If we find another instance of life then the probability immediately shifts to it being highly likely there is lots of life out there but whilst we have only one instance no such assumption can be made.


I agree with your analysis completely, except that I must hold onto the possibility of panspermia, and that the DNA may have been seeded on Earth from elsewhere, holding out the possibility that it was seeded to a number of different planets at the same time. So then, the idea that related life exists elsewhere is not so improbable at all, but even quite likely.


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## Mirannan (Jul 23, 2017)

Dave said:


> I agree with your analysis completely, except that I must hold onto the possibility of panspermia, and that the DNA may have been seeded on Earth from elsewhere, holding out the possibility that it was seeded to a number of different planets at the same time. So then, the idea that related life exists elsewhere is not so improbable at all, but even quite likely.



Regarding hypothetical Europan or Martian life: IMHO if we find either of these it might not change anything much. Why?

Because there is sufficient exchange of material between Solar System bodies (for example, meteorites blasted off Mars found on Earth) that a colony of bacteria inside Earthly or Martian rocks (or Europan ice) could have been transported between the various bodies - especialy given the huge amount of time available.

Therefore, if we find life on Europa and it looks just like Earthly life in biochemistry (even if there are minor differences) we still don't know whether a) Europan bugs originated on Earth or Mars or b) Earth's life chemistry is the only one possible - the latter I find unlikely as, for example, there are hundreds of amino acids and nucleic acid bases that Earth life hasn't used. There is also the issue of chirality. Also the potential issue of contamination from the probe itself, of course. So Europan life just like ours tells us very little. 

However, if we find life elsewhere in the Solar System and it has radically different biochemistry - that changes everything. It means that the formation of life is easy and maybe inevitable. Earthlike worlds may be rare in the Universe, but I much doubt that icy moons with a water mantle are.

Incidentally, extrasolar panspermia is much more difficult. The distances involved are many orders of magnitude greater, and the energies are big enough that meteors are difficult to get to the right speed and if they were formed they would probably be sterile.


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## SilentRoamer (Jul 23, 2017)

Brian G Turner said:


> What stands out for me on that is that Newtonian physics was, for its time, a very good description of the universe as we perceived it then - with a few clear problems.
> 
> However, Einstein's theories are little different nowadays. There remains the issue of Relativity being unable to account for the motion of stars in a galaxy, for example. Every time we read/hear about "dark matter" or "dark energy" we are basically discussing the failure of Relativity to describe the observable universe, and underlining how incomplete our understanding of physics still is.



I think this is a very good point Brian. Although I don't think "dark matter" is a failure of relativity, I think it is just the last remaining value to ascribe to a physical property. I think the real problem is the unification of Quantum and Standard Theory, the micro and the macro. Specifically Quantum effects and Gravity. 



Vertigo said:


> I make no absolute assumptions but I do consider the weight of evidence to point to certain conclusions being far more likely than others.



This is what the scientific theory is all about. I have beliefs, I believe certain physical laws are independent of temporal or physical variance anywhere in the OU - the speed of light being one of them. However my beliefs aren't so that I can't accept the possibility science may discover some hitherto undiscovered properties of spacetime that allow us to break current constraints. 



Parson said:


> Is that a potential answer to the question of the "speed" of gravity?



I'm fairly certain that the current ocnsensus of Gravity wave propagation is speed of light. However it may be instant, but even if it is isn't there is no physical matter to move and no necessary breach of c.



Brian G Turner said:


> That's another seriously interesting point - we've discussed studies here before now that suggest that universal constants in physics might be neither universal, nor constant.
> 
> In this example, the value of C might be different in different areas of the universe (and in time), according to context. I can't recall anything specific to C (though on a side note, the speed of light does vary according to the medium it passes through. As a constant, the value of C is defined as through a vacuum, but vacuums themselves can be seriously interesting for the fact that they aren't!).



True, vacuums aren't fully vacuums. There are all sorts of Quantum events and abstract virtual particles and all sorts weird goings on. Vacuums do contain some energy I think. 

WRT the speed of light, I am fairly sure there are a lot of peer reviewed studies that show if the speed of light were variable across the OU then we would see certain things - such as red and blue shift variance from expected measurements when looking at distant galaxies and we just don't see that. 



Dave said:


> I agree with your analysis completely, except that I must hold onto the possibility of panspermia, and that the DNA may have been seeded on Earth from elsewhere, holding out the possibility that it was seeded to a number of different planets at the same time. So then, the idea that related life exists elsewhere is not so improbable at all, but even quite likely.



I always think life starts (or at least the checmial components start) in the great nebulae, chaotic areas in space, bathed in radiation, then comets pick up the seeds and spread them around. We haven't seen abiogenesis on Earth so maybe it didn't happen on Earth. Or maybe it was a miraculous event. I go for the former.


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## SilentRoamer (Jul 23, 2017)

A mod could probably move this thread from about two pages back into another thread - as it's way off topic.

A very good and sensible discussion though and some really interesting viewpoints.


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## Vertigo (Jul 23, 2017)

Brian G Turner said:


> If life arose here because of natural processes - no matter how common or rare - then it must be presumed to take place elsewhere. This is especially when we are continually surprised by the diversity life on our own planet, and the fact we haven't even begun properly exploring our own star system.
> The alternative is surely that life is a miracle and therefore works outside the laws of physics?


That's what I really want to believe but the alternative doesn't have to be a miracle, just an incredibly unlikely occurrence, for example (and I'm no biochemist so this is just throwing stuff in!) maybe the beginnings of the first cell might have been triggered by a single cosmic ray blatting (good scientific term that) a bunch of organic molecules in just the right way to kick start it. We just don't know exactly what started it going; there are many possible explanations that have been put forward but, to the best of my knowledge, none have proved to be repeatable in the lab 'under natural' conditions. In fact my personal belief is that it's most likely that simple life - bacteria and archea analogues - are quite common. I'm not so sure about complex life like eukaryote analogues. However the only point I was making is that until we find other life and, as said below, it needs to be unrelated to Terran life, no sensible statistical predictions can be made and it comes down to being a question of belief.



Dave said:


> I agree with your analysis completely, except that I must hold onto the possibility of panspermia, and that the DNA may have been seeded on Earth from elsewhere, holding out the possibility that it was seeded to a number of different planets at the same time. So then, the idea that related life exists elsewhere is not so improbable at all, but even quite likely.


My problem with panspermia is that we're just pushing the question further back. If life came here via panspermia then the next obvious question is: is there only one form of panspermia life or have there been multiple abiogenesis events resulting in multiple 'strain' of panspermia? Ultimately the same question is being posed one single abiogenesis event or multiple abiogenesis events.


Mirannan said:


> Regarding hypothetical Europan or Martian life: IMHO if we find either of these it might not change anything much. Why?
> 
> Because there is sufficient exchange of material between Solar System bodies (for example, meteorites blasted off Mars found on Earth) that a colony of bacteria inside Earthly or Martian rocks (or Europan ice) could have been transported between the various bodies - especialy given the huge amount of time available.
> 
> ...


You are, of course, exactly right; the only thing that will really tip the scales is finding life that is clearly unrelated to Terran life.

Great discussion! But you're probably right that it maybe ought to be in its own thread  Sorry think I might have been one of the first de-railers...


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## Serendipity (Jul 23, 2017)

Brian G Turner said:


> We're kind of off-topic here from a possible Planet 10 here, and into an interesting subject in it's own right.
> 
> What stands out for me on that is that Newtonian physics was, for its time, a very good description of the universe as we perceived it then - with a few clear problems.
> 
> ...



Could we not make planet 10, the planet of imagination?

Hen's teeth, I'm away for a day or so and there's a whole load of interesting comments to catch up on! I don't know where to start!


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## Serendipity (Jul 23, 2017)

Turning to some (of the many) serious topics here....


The speed of light is associated with electromagnetics. We already have the strong and week nuclear forces linked to electromagnetics. Gravity seems to be restricted to the speed of light. So somehow there is very likely to be a connection between gravity and electromagnetics. So basically all four fundamental forces are limited by the speed of light. But is mass, any mass, formed of one of these four fundamental forces? Or are mass and forces very much distinct? If the latter, then what is there to stop mass going faster than the speed of light?
Quantum Entanglement Messaging: I have a very simple mechanism for passing on messages between two places at faster than the speed of light if the set up of the entangled particles is already in place. A particle, when viewed, would be in either of two states. All you would need to do is view the particle at one end to set the state of the entangled particle at the other end. Now if you have a set of particles you can open as many boxes as there are entangled particles. If you stop at an odd number of occurrences of a certain state, then you can designate that as zero. Similarly if you stop at an even number of occurrences, you can designate that as one. Before you know, we can have communication as computers know it  and we all know they can send messages. Of course this is dependent on being able to read the state of the particles at the other end. [And, if you're unlucky enough to have a very large number of the wrong state occurring, you can always rely on standard error correction methods used in communicating messages today!][Er... should I have applied for a patent for this idea?]
Alcubierre's Drive: I'll be digging out the papers on this later this coming week... so expect some response when I can get my head around them.
As to whether we will find life elsewhere in our universe depends oddly enough on the definition of what life is. So far we, as a human race, have concentrated our searches on the one route to life that we know was a success, namely us. That's not unreasonable, given our limited resources. But what if we really could have a silicon-based life form using chemical compounds in a different way? 
O.K. that's enough wooden spoon stirring from me for today....


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## Brian G Turner (Jul 23, 2017)

Have split this discussion on physics into its own thread.


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## SilentRoamer (Jul 23, 2017)

Serendipity said:


> Turning to some (of the many) serious topics here....
> 
> 
> The speed of light is associated with electromagnetics. We already have the strong and week nuclear forces linked to electromagnetics. Gravity seems to be restricted to the speed of light. So somehow there is very likely to be a connection between gravity and electromagnetics. So basically all four fundamental forces are limited by the speed of light. But is mass, any mass, formed of one of these four fundamental forces? Or are mass and forces very much distinct? If the latter, then what is there to stop mass going faster than the speed of light?


Mass and energy are equivalences - under the right circumstances they are interchangeable but that's not the same as being the same thing. Two £5 notes are not the same as a £10 although they have an equivalence.

The main thing preventing mass going faster than light are the energy requirements. As you approach c the amount of energy you need to continue accelerating approaches an arbitrarily large number - with the final outcome being an infinite energy requirement to achieve the speed of light - note we are not talking about faster than the speed of light but the speed of light itself. It takes an infinite amount of energy to accelerate any object with mass to the speed of light.

This is to say nothing of cause > effect, if you can send anything faster than light - then you have effect > cause. c isn't just the speed of light, its the speed limit for information exchange - if something can break that speed limit it can arguable provide a state for a system BEFORE a measurement. This wouldn't just change the laws of physics, it would change physical reality, it would essentially send the arrow of time spinning.

All physical laws that can be known and measured are constrained by the almighty invariance of c. Thankfully! 

Worth remembering though that modern science treats light as both a physically discreet object (photon) and also as a statistical waveform where the photon resides in all probabilities until the measurement is made (for anyone interested the best way to understand this is to study the double slit experiment.) We are specifically using the Newtonian explanation of light and gravity.

Earlier someone mentioned inflation and how things travelled faster than c - that's not really true. The metric scale expansion of space was just happening at a bigger level, the best analogy I can provide for this is:

Draw a load of little galaxy shapes on a balloon before you blow it up - now imagine that those galaxies are embedded in a 4 dimensional surface, blow up the balloon and the points all move away from each other - but none of them actually move - the scale of the distances just increases. If you can hold this in your mind whilst also taking into consideration the speed of light - it is the explanation why there are no physical edges to space we can see - only temporal edges.


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## Vertigo (Jul 23, 2017)

Serendipity said:


> Turning to some (of the many) serious topics here....
> 
> 
> The speed of light is associated with electromagnetics. We already have the strong and week nuclear forces linked to electromagnetics. Gravity seems to be restricted to the speed of light. So somehow there is very likely to be a connection between gravity and electromagnetics. So basically all four fundamental forces are limited by the speed of light. But is mass, any mass, formed of one of these four fundamental forces? Or are mass and forces very much distinct? If the latter, then what is there to stop mass going faster than the speed of light?
> ...


1. Okay I'll take a stab at this though someone more knowledgeable will probably be able to do better. So The equations say (and this is very much confirmed by observation) that mass is intimately tied in: E = mc^2. The fundamental relativity equation. When all the sums are done you find that as a particle's speed approaches the speed of light so its mass approaches infinity and so an infinite amount of energy is required to accelerate it further. The only particles (I think) that actually travel at the speed of light are massless particles like photons. Now's where it gets a little horrible: The prior statement is only from the outside observer's point of view. From the subjective point of view, the traveller's point of view if you like, your mass stays the same and indeed you _appear_ to exceed the speed of light; as you approach the speed of light you will subjectively appear to cross say 1 light year in significantly less than a year. How can this be possible? Well the catch is time dilation; as you approach the speed of light your internal clock slows down relative to the outside world so, whilst to the outside world it looks like it takes you say 1.5 years to cross that 1 light year distance, it seems like only say 8 months to you (those are only rough invented figures not calculated ones by the way). And time dilation is again a measureable effect and one that, for example, must be taken into account to get accurate GPS readings. So I'm afraid pretty much everything in physics is interrelated in this way: mass, energy, speed of light etc.
Ah @SilentRoamer got there ahead of me!!!

2. I thought of that one as well and I actually think it could work but there are, as I see it, a couple of provisos:
a. You're going to need a lot of entangled particles. Charles Stross addresses this one quite well in his Eschaton books. They have FTL comms, which does indeed cause all sorts of causality issues which is actually largely what the books are about. However your supply does get exhausted; once observed that pair cannot be used again. In the Eschaton books this is very expensive as you have to constantly be sending new entangled particles across space _conventionally_ before they can be used.
b. This is the difficult one. The receiver must know exactly when the sender is going to transmit. Why? Because they must not observe the particle until the sender has done so otherwise they become the transmitter and, so far as I know, there's no what the receiver can know when the sender has done their observation. In other words the communication must always be done at prearranged times. Which is a bit of a limitation (that Stross conveniently ignored).

3. I await your further input!!  Actually Alcubierre drives are something I know little about. I understand the basic idea, but I don't understand the detailed arguments for and against. In Cixin Liu's Three-Body Problem books he uses a similar physical concept to the Alcubierre drive but it is, I think, a little different. In his books they flatten space time around the spaceship allowing massive acceleration as you are not working against a gravity gradient. Or something like that; I was a little confused.

4. Life can actually be simplified down to a fairly simple statement (I think). Life is self replicating chemicals in which the aggregate entropy _decreases_ instead of the more normal increase. I think that's a little short actually; there's things like energy gradients involved as well. And I'm not sure anyone has yet figured out a full set of silicon based chemical reactions that will achieve this. Again I'm on slightly shaky ground here but there are certainly other chronners know more about this one than me (I know @Stephen Palmer has looked into this area a lot). The other argument on this one is that we've got a lot of silicon in this solar system but so far no sign of this happening.


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## Danny McG (Jul 23, 2017)

Vertigo said:


> The one thing we can never do though is break the rules of physics.



My inner Trekkie is pleading for you to say this in a Scottish accent


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## Brian G Turner (Jul 23, 2017)

SilentRoamer said:


> the double slit experiment



A photon walks into two bars. But is only seen in one ...


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## Venusian Broon (Jul 23, 2017)

PHYSICS PEDANT INCOMING....



Vertigo said:


> 1. Okay I'll take a stab at this though someone more knowledgeable will probably be able to do better. So The equations say (and this is very much confirmed by observation) that mass is intimately tied in: E = mc^2. The fundamental relativity equation.



It's the 'poster boy' of equations, because it is very simple, but I'd say the more fundamental equation it's derived from is a bit more complex, but more general :    
	

	
	
		
		

		
			





Now to just to stir the pot the little - regarding this observation:


> The speed of light is associated with electromagnetics. We already have the strong and week nuclear forces linked to electromagnetics. Gravity seems to be restricted to the speed of light. So somehow there is very likely to be a connection between gravity and electromagnetics. So basically all four fundamental forces are limited by the speed of light. But is mass, any mass, formed of one of these four fundamental forces? Or are mass and forces very much distinct? If the latter, then what is there to stop mass going faster than the speed of light?



According to Relativity, Gravity emerges from the interaction of mass and space-time. Is Gravity then a fundamental force? Now people looking for theories of everything tried adding new dimensions from the normal four used in General Relativity and found that by adding another dimension, one could derive the equations we use for EM. Hence there is possibility that just by adding lots of dimensions one can derive all the known forces - a reason I think why string theory's usually start out with about 13 of them!

I suppose like Vertigo and SilentRoamer, one cannot say that mass and forces are distinct, the above is saying that the 'fundamental' forces are really just emergent features that arise from the interaction between spacetime, mass and energy.

Of course this is a Relativistic view - QM would disagree!




Vertigo said:


> 3. I await your further input!!  Actually Alcubierre drives are something I know little about. I understand the basic idea, but I don't understand the detailed arguments for and against. In Cixin Liu's Three-Body Problem books he uses a similar physical concept to the Alcubierre drive but it is, I think, a little different. In his books they flatten space time around the spaceship allowing massive acceleration as you are not working against a gravity gradient. Or something like that; I was a little confused.



Ah proper Science fiction...find me some particle with negative mass then we can talk about trying to put a working Alcubierre drive together. Otherwise we might as well count angels dancing on the heads of pins. 

From memory someone stated that if gravity waves could not be found, there might be a case that areas of space holding negative mass were dampening them down...unfortunately we have discovered gravity waves, so that knocks that one out!  

Negative mass / Negative energy density is one of those things that are very easy to mathematically imagine, but physically much less so.



Vertigo said:


> 4. Life can actually be simplified down to a fairly simple statement (I think). Life is self replicating chemicals in which the aggregate entropy _decreases_ instead of the more normal increase.



I disagree with this statement. The laws of thermodynamics, like the speed of light, are pretty tight and although still an assumption and therefore possibly able to be broken, if they were broken it would be a _major _breakdown in our understanding of physics.

When you take into account all the various elements that come together that make life I'm pretty sure entropy, as ever, increases.


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## Vertigo (Jul 23, 2017)

Venusian Broon said:


> PHYSICS PEDANT INCOMING....
> 
> 
> 
> It's the 'poster boy' of equations, because it is very simple, but I'd say the more fundamental equation it's derived from is a bit more complex, but more general :


My physics education is far too far back for me to remember that one! 


Venusian Broon said:


> I disagree with this statement. The laws of thermodynamics, like the speed of light, are pretty tight and although still an assumption and therefore possibly able to be broken, if they were broken it would be a _major _breakdown in our understanding of physics.
> 
> When you take into account all the various elements that come together that make life I'm pretty sure entropy, as ever, increases.


As I understand it local entropy can decrease so long as overall entropy either increases or remains the same. There are a lot of chemical reactions that decrease entropy locally but increase entropy overall (typically by heating the outside environment). So here is Nick Lane on the subject which is where I got it:



> Many substances accumulate to levels that far exceed their natural thermodynamic equilibrium, because they react very slowly. If given a chance, oxygen will react vigorously with organic matter, burning everything on the planet, but this propensity to violence is tempered by a lucky chemical quirk [a kinetic barrier] that makes it stable over aeons. Gases such as methane and hydrogen will react even more vigorously with oxygen but again the kinetic barrier to their reaction means that all these gases can coexist in the air for years at a time, in dynamic disequilibrium... They can be coerced into reacting, and when they do they release a large amount of energy that can be harnessed by living cells; but without the right catalysts nothing much happens. Life exploits these kinetic barriers, and in so doing increases entropy faster than would otherwise happen. Some even define life in these terms, as an entropy generator. Regardless: life exists precisely because kinetic barriers exist - it specialises to break them down. Without the loophole of great reactivity pent up behind kinetic barriers, it's doubtful that life could exist at all.


Also:


> Respiration _conserves_ some of the energy released from that reaction ['burning' food in Oxygen] in the form of ATP [a sort of chemical battery used by life], at least for the short period until ATP is split again [releasing the stored energy as heat]. In the end respiration and burning are equivalent; the slight delay in the middle is what we know as life.


Good stuff! This is from his book The Vital Question recommended by @Stephen Palmer and enthusiastically seconded by me! 

Essentially, as I understand it, life decreases local entropy by creating order (our bodies) but it does so by increasing the external entropy and, of course, it is only temporary; when our bodies decay all that stored order is released.

But I should add that I only mentioned the life issue as an other example of science versus faith. I have faith that there is other life out there but so far the science has not proved it.


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## Vertigo (Jul 23, 2017)

dannymcg said:


> My inner Trekkie is pleading for you to say this in a Scottish accent


One thing we cannae do Cap'n is break the laws of physics.. [better?]


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## Brian G Turner (Jul 23, 2017)

I thought the argument that life defied entropy was simply because it was being considered as a limited system in isolation to the rest.

Simply put, the sun powers the existence of all the major forms of life on Earth - therefore the supposed decrease in entropy from the development of complex life is outweighed by the massive increase in entropy through the sun's energy output, of which only a tiny proportion is used.

Or something like that.


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## Venusian Broon (Jul 23, 2017)

Vertigo said:


> Essentially, as I understand it, life decreases local entropy by creating order (our bodies) but it does so by increasing the external entropy and, of course, it is only temporary; when our bodies decay all that stored order is released.



The quote you had seemed to suggest to me that life actually increases total entropy faster (of the local system) which kinda makes sense to me. So tentatively, the more complex the organism/plant/animal the more energy and materials are required just to maintain its complexity - hence you 'burn through' entropy faster .

Interestingly I was watching a refutation of breatharism and someone did the mathematics on respiration (his argument was that if these practioners of breatharism produced carbon dioxide in their breaths then they were respiring just like the rest of us and not surviving on some strange 'energy') and I found it quite surprising, as I'd never calculated it before, that an average human loses ~35 grams of mass every hour just through breathing. 35 gram of sugars being slowly 'burnt' just to keep you going every hour - never mind doing anything more complex, like needing to replace proteins etc...

I suppose I'm always thinking of processes rather than things when someone mentions entropy, as one could wonder how something as ordered as an ice crystal could 'defy' entropy, but there was a process that created the crystal and you need to analyse that process. Which _should _always have entropy increase!


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## LordOfWizards (Jul 23, 2017)

Well, I'm very pleased with this thread so far. Everyone is not only keeping civility, but quoting mostly accurate sources, and admitting when their notions are basically conjecture. Currently, there are fairly diverse interpretations of modern physics, and plenty of unknowns.

Someone mentioned "The Speed of Gravity" earlier. Now common assumption based on actual measurements (Gravity waves, Pulsars measured lensing by Jupiter, the perihelion of Mercury, etc.) is that General Relativity is an accurate representation of the "speed of gravity", and that it appears to agree completely with Einsteins Field Equations in predicting that gravity travels at light speed. (Advanced scientific Paper on the topic)

Yet there are schools of thought, and one rather compelling paper (here) that argues quite logically that it would seem as if Gravity may well travel much faster than light, and therefore offer some future avenue that harnesses gravity to exceed the speed of light.

One question that comes to mind for me is this component of special relativity that suggests mass cannot be accelerated to the speed of light without infinite energy. If that is truly the case the how is it that mass can be converted into energy by splitting the atom? Well, the answer is that it just isn't that simple. The Equation _E_ = _mc_2 merely implies that matter can be converted into energy, and that really isn't what's happening. Yes, some mass appears to have "disappeared" in the reaction, but it was mass in the form of alpha particles and nuclei particles that according to certain quantum theories aren't really masses at all. They are energy states. Eigenvalues in a wave equation. 

It all makes more sense if you think of mass as just another form of energy, and what's going on is a conversion from one type of energy to another. Specifically in the case of atom bombs: Potential energy converted into Kinetic energy. 

I tend to be of the camp that says: We are not there yet. There are too many complexities and contradictions in modern Physics to be absolutely certain on the question of FTL, or any other possible immensely advanced technology. Einstein himself said that "Imagination is more important than knowledge." I whole-heartedly agree. This is why I love science fiction. Has anyone else noticed how often science fiction ends up becoming science fact?


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## Venusian Broon (Jul 23, 2017)

LordOfWizards said:


> It all makes more sense if you think of mass as just another form of energy, and what's going on is a conversion from one type of energy to another.



That's a good way of thinking about it - all matter is a particular 'condensate' of the original energy unleashed in the big bang. As the universe expanded and cooled so that it could no longer spontaneously form matter-antimatter pairs it was an asymmetrical quirk in a particular particle/anti-particle decay that had lead to an imbalance of matter so that when all the antimatter was extinguished there was enough left over to form all the lovely hydrogen, helium and lithium that we needed to start seeding the first stars.

At least that's how we think it all happened. At the moment.  





LordOfWizards said:


> Has anyone else noticed how often science fiction ends up becoming science fact?



What's the saying? "Be careful for what you wish for."

Some science fiction ends extremely badly for us humans


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## Vertigo (Jul 24, 2017)

Venusian Broon said:


> The quote you had seemed to suggest to me that life actually increases total entropy faster (of the local system) which kinda makes sense to me. So tentatively, the more complex the organism/plant/animal the more energy and materials are required just to maintain its complexity - hence you 'burn through' entropy faster .
> 
> Interestingly I was watching a refutation of breatharism and someone did the mathematics on respiration (his argument was that if these practioners of breatharism produced carbon dioxide in their breaths then they were respiring just like the rest of us and not surviving on some strange 'energy') and I found it quite surprising, as I'd never calculated it before, that an average human loses ~35 grams of mass every hour just through breathing. 35 gram of sugars being slowly 'burnt' just to keep you going every hour - never mind doing anything more complex, like needing to replace proteins etc...
> 
> I suppose I'm always thinking of processes rather than things when someone mentions entropy, as one could wonder how something as ordered as an ice crystal could 'defy' entropy, but there was a process that created the crystal and you need to analyse that process. Which _should _always have entropy increase!


Yes my understanding from the book is that it does exactly that; quite massively increase the total entropy. When I said life decreases the local entropy I meant local to the body of the lifeform, rather than local to the environment it was in.

One of the incredible (and relevant) statistics to come out of that book was just how 'inefficient' a process life is:



> Modern cells [using enzymes] minimise their energy requirements, but we have already seen that they still get through colossal amounts of ATP, the standard energy 'currency'. Even the simplest cells produce about 40 times as much waste from respiration as new biomass. In other words, for every gram of new biomass produced, the energy-releasing reactions that support this production must generate at least 40 grams of waste. *Life is a side reaction of a main energy-releasing reaction*. That remains the case today, after 4 billion years of evolutionary refinement. If modern cells produce 40 times more waste than organic matter, just think how much the first primitive cells, without any enzymes, would have had to make! Enzymes speed up chemical reactions by millions of times the unconstrained rate. Take away those enzymes, and throughput would need to increase by a similar factor, say a millionfold, to achieve the same thing. The first cells may have needed to produce 40 tonnes of waste to make 1 gram of cell!


(my highlighting the key bit relevant to entropy)(and don't I wish I had bought that book in eBook form making cut and paste possible....)

ETA: Incidentally I had never heard of Breatharianism before...


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## Venusian Broon (Jul 24, 2017)

Vertigo said:


> One of the incredible (and relevant) statistics to come out of that book was just how 'inefficient' a process life is:
> 
> 
> (my highlighting the key bit relevant to entropy)(and don't I wish I had bought that book in eBook form making cut and paste possible....)



I do remember reading an article in NS that actually modern Eukaryote cells (the ones that make all higher animals) are in fact highly inefficient - in terms of the mechanisms they use and how they process materials - and that most bacteria are, in a general sense, much more streamlined and energy efficient. Which means that the first cells, being bacterial in nature, were perhaps not as clunky and as inefficient as Nick Lane is suggesting!

The author of the article was suggesting that because of this divide it suggested that although it seems quite easy for bacterial organisms to spring into existence (they seem to have appeared on Earth as soon as the conditions allowed them too) and therefore likely to be everywhere in the universe, the step to Eukaryote cells and multi-cellular creatures might be a very improbable step, as it appears to be a _backwards_ step when comparing individual cells.

Anyway we appear to be drifting well away from physics at the mo'...


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## Vertigo (Jul 24, 2017)

Venusian Broon said:


> I do remember reading an article in NS that actually modern Eukaryote cells (the ones that make all higher animals) are in fact highly inefficient - in terms of the mechanisms they use and how they process materials - and that most bacteria are, in a general sense, much more streamlined and energy efficient. Which means that the first cells, being bacterial in nature, were perhaps not as clunky and as inefficient as Nick Lane is suggesting!
> 
> The author of the article was suggesting that because of this divide it suggested that although it seems quite easy for bacterial organisms to spring into existence (they seem to have appeared on Earth as soon as the conditions allowed them too) and therefore likely to be everywhere in the universe, the step to Eukaryote cells and multi-cellular creatures might be a very improbable step, as it appears to be a _backwards_ step when comparing individual cells.
> 
> Anyway we appear to be drifting well away from physics at the mo'...


I seem to recall that it wasn't quite such a one sided argument. In some respects eukaryotes are more inefficient but in other they are more efficient. I think the main reason for the inefficiency is the difference in the genome. Bacteria typically have around 5,000 genes eukaryotes have about 20,000 ranging up to 40,000; a single e. coli bacterium has around 13,000 ribosomes, whereas a single liver (eukaryote) cell has at least 13 million. This makes the burden of protein synthesis and cell division much higher for eukaryotes. On the other had it lets them become much bigger and more complex... However, as I recall, the statement above referring to primitive cells is actually referring to the common ancestors of bacteria and archaea before the two diverged. Certainly modern bacteria use enzymes, I just can't remember quite when that evolved.

But of course you are quite right this is just another diversion!


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## Brian G Turner (Jul 24, 2017)

This month's _BBC Sky at Night_ magazine (available for free on Amazon for Prime members: BBC Sky At Night Magazine: Amazon.co.uk: Kindle Store) has a feature on the question of panspermia. It's a little short, but there is for/against section which basically boils down to:

FOR: All evidence points to panspermia being entirely possible, even probable. Experiments have demonstrated that simple organisms can survive even the harsh conditions of space.
AGAINST: Solid evidence of life on other planets is required before panspermia is accepted, otherwise the danger is of simply pushing back the origins of life rather than addressing it

(the latter, of course, reflects what Vertigo said earlier!).

What's especially interesting is that the for argument is provided for by Chandra Wickramasinghe, who postulated a hypothesis for pansermia with Fred Hoyle back in the 70's/80's. I have one of his books, and while I agree with some of his ideas, he's very much a fringe thinker - I'm given the impression he considers life as statistically improbable to the point where he seems to be arguing a single origin for life, rather than it being a natural development within the laws of chemistry - something I'd argue for (though I may have misunderstood his opinion).

Also for Amazon Prime members, I noticed there are some "graphic novels" available for free download that provide basic intros to major branches of physics - I've just downloaded the ones on _Relativity_, _Quantum Physics_, and _Particle Physics_ to double-check my understanding. 
Amazon.co.uk: Comics & Graphic Novels: Kindle Store

(Note: These are for the UK - I'm not sure what's available on Amazon.com for our US members).

[EDIT: And here are the free magazines for UK Amazon Prime members: Magazines]


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## Vertigo (Jul 24, 2017)

Brian G Turner said:


> FOR: All evidence points to panspermia being entirely possible, even probable. *Experiments have demonstrated that simple organisms can survive even the harsh conditions of space. *
> AGAINST: Solid evidence of life on other planets is required before panspermia is accepted, otherwise the danger is of simply pushing back the origins of life rather than addressing it.


I have a bit of a problem (though I haven't seen the whole argument) with the highlighted comment. Just because they can doesn't mean they will. Also as @Mirannan commented; whilst intrasolar panspermia might be possible, even likely, extrasolar is much more problematical; that requires the organisms to not only survive in space but to survive for the millienia it would take for them to cross interstellar space without FTL (d'you see what I did there!) and whilst being bombarded, unprotected, by cosmic rays. So if they didn't cross interstellar space then they either originated on a planet in the solar system (back to square one) or they evolved in space.

Life evolving in space is still problematic, I think. Yes, organic molecules can form, that's very easy, but life requires an energy barrier to create an energy gradient. All modern life now does this with biochemistry - very complex cell walls that provide an energy gradient that allows some, but not too many, protons to cross - but something as complicated as that just isn't going to occur spontaneously (not without intelligent design). This is one of the arguments for life evolving at alkaline hydrothermal vents, as it has been shown that such barriers and gradients occur naturally within their structure and would be suitable for the beginnings of the processes of life. I don't know but I think such would be very unlikely in a place where liquid water (another essential component of our abiogenesis) would be very unlikely.

Nick Lane actually argues that any planet in the universe that has tectonic activity and water is likely to have alkaline hydrothermal vents and so its likely to produce simple life. What he's much less confident about is that life evolving to form complex life (eukaryote analogues).


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## Brian G Turner (Jul 24, 2017)

Vertigo said:


> that requires the organisms to not only survive in space but to survive for the millienia it would take for them to cross interstellar space



Not simply millenia, but millions of years. However, at that point we're talking about any organisms being frozen within bodies of ice. Which is going to provide some degree of protection until that ice actually thaws, but demand an incredible degree of resilience.



Vertigo said:


> Life evolving sin space is still problematic, I think.



I agree. Even with my science fiction hat on I'd say it may be possible, but not necessarily probable. However, every discovery about space continues to confound our expectations, so I personally wouldn't shut the door entirely on that one.

What I think is more likely is for essential organic molecules to end up being carried into star systems, where they end up on planets/moons or similar bodies. In most instances, to no effect. But in rare ideal situations, abiogenesis occurring as a natural physical process where conditions allow.

Over time, such a planet or moon may be struck by other bodies, causing material to be ejected into space, sometimes carrying such organisms. In most instances, such material will remain within that star system. Where they reach other ideal environments on other planets or moons, then development can continue to take place.

However, we also know there are instances where more violent events can eject entire planets or moons from solar systems - massive Jupiter-like planets as they spiral toward their host star, for example. As I understand it, space can be presumed to be filled with wandering planets and moons precisely because of such mechanics.

Any life therefore carried on such bodies may have a chance to then spread to other solar systems that are reached, as per the original assertion.

All that's required is for any organism - or genetic material - to remain preserved and viable. On that point, I also want to invoke rogue RNA as a way for such material to perhaps not simply start new life, but also change any existing life that may be encountered through horizontal gene transfer.

All this may sound a little far-fetched to some, but while such events may seem rare and improbably in a human time frame, in a cosmological one counted over billions of years I would argue we're talking about probable periodic events.

Not only that, there is tantalising evidence that our own solar system, and even the development of life on Earth, may have undergone multiple such events.

Direct proof for much of this remains limited at present. However, so much of what I've read in the science press over the past couple of decades seems to suggest this sort of model  - in whole or in part - as increasingly probable.

2c.


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## Vertigo (Jul 25, 2017)

Ah there we come to a definition of panspermia I guess, as I wouldn't consider organic molecules travelling through space to be life and therefore I wouldn't consider them to be panspermia. Life crossing interstellar space embedded in ice or on rogue planets I wouldn't discount as impossible but in either case they will still be unprotected from the horrendous levels of cosmic radiation. Within a stellar system I can certainly see the potential for life crossing between planets.

But I would stress that when I talk panspermia I am specifically talking about life rather than it's building blocks.

And, oh dear, we seem to be in danger of derailing the derailed thread!


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## Dave (Jul 25, 2017)

Vertigo said:


> But I would stress that when I talk panspermia I am specifically talking about life rather than it's building blocks.


I was, however, most certainly thinking only of its building blocks. If I require a different word to be created for this then that may be  required (the dictionary definition of panspermia seems to be one regarding spores and germs.) I certainly don't think life itself can travel extra-solar (even spores or germs) unless it is intelligent enough to build FTL ships to carry it.


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## Serendipity (Jul 25, 2017)

Dave said:


> I was, however, most certainly thinking only of its building blocks. If I require a different word to be created for this then that may be  required (the dictionary definition of panspermia seems to be one regarding spores and germs.) I certainly don't think life itself can travel extra-solar (even spores or germs) unless it is intelligent enough to build FTL ships to carry it.



Um... what about stars passing close enough to each to be able to transfer life's building blocks from one system to another? We had a recent example of Scholz's star that passed within 0.82 light years of the Solar System 70,000 years ago. See Scholz's star - Wikipedia


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## Vertigo (Jul 25, 2017)

Serendipity said:


> Um... what about stars passing close enough to each to be able to transfer life's building blocks from one system to another? We had a recent example of Scholz's star that passed within 0.82 light years of the Solar System 70,000 years ago. See Scholz's star - Wikipedia


Fascinating I was completely unaware of that! Thanks!

However:


> Comets perturbed from the Oort cloud would require roughly 2 million years to get to the inner Solar System.[2] At closest approach the system would have had an apparent magnitude of about 11.4.[4] A star is expected to pass through the Oort Cloud every 100,000 years or so


That would suggest the life would still be subjected 2 million years of exposure to deep space and associated radiation damage before it reached the inner system. Also life would have had to reach that far out in the 'donating' system in the first place in order for the exchange to take place. But still interesting all the same!


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## Danny McG (Jul 25, 2017)

What a quote....

"We had a recent example of Scholz's star that passed within 0.82 light years of the Solar System 70,000 years ago"

Only 70,000 years ago eh? That IS recent


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## Serendipity (Jul 25, 2017)

Vertigo said:


> Fascinating I was completely unaware of that! Thanks!
> 
> However:
> 
> That would suggest the life would still be subjected 2 million years of exposure to deep space and associated radiation damage before it reached the inner system. Also life would have had to reach that far out in the 'donating' system in the first place in order for the exchange to take place. But still interesting all the same!



Scholz's star came in as far as 52,000 astronomical units from the Sun - which equates to the inner edge of the Oort cloud. Apparently we should by laws of probability expect a star to come INSIDE the Oort cloud once every 9 million years, i.e. much closer than Scholz's star. So the potential for transferral of life would very much increase under these circumstances...

However, these numbers do beg some very interesting questions in themselves - like can there be a hidden very small dark star locked into orbit around our Sun or did life as we know it start in another star system from us?


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## Venusian Broon (Jul 25, 2017)

Vertigo said:


> Fascinating I was completely unaware of that! Thanks!
> 
> However:
> 
> That would suggest the life would still be subjected 2 million years of exposure to deep space and associated radiation damage before it reached the inner system. Also life would have had to reach that far out in the 'donating' system in the first place in order for the exchange to take place. But still interesting all the same!



I thought this too, but actually being embedded in ice is about the best possible protection from cosmic rays - even better than heavier elements. As it stands cosmic rays can penetrate up to about 3km into the Earths crust (although I don't know if that is because the most energetic rays finally get snuffed out at that level or that's as deep as we can mine at the moment!)

I see calculations that a water shield of one metre is enough to reduce radiation to terrestrial background levels - although I can't vouch that is true.

Hence 'dirty snowballs' or really big chunks of Oort/Kupier belt objects are the ideal transport - also given that extremophile life would also likely have a very slow metabolic rate in frozen conditions. Nice for the long journey times - although if they are not just frozen solid and just packaged, they will need some form of energy, however small to just eek by.

However this does not explain how they got there in the first place - could these ice objects be common 'nurseries' that always have the conditions for very simple life to appear (so that they are absolutely everywhere?)

If this was the case then spreading into inner systems and rocky worlds is then quite easy - not only are all these objects subject to all sorts of gravitational disturbances with bigger objects knocking them about all over the place, but big events such as supernova's could really push huge amounts all over the place.


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## Vertigo (Jul 25, 2017)

Well not quite 'much closer' Scholz's star came to 52,000AU and we can expect as close as that or closer once every 9 million years. The Oort cloud is believed to range from around 50,000AU 100,000-200,000AU. But that is very theoretical we can't detect bodies of that size that far out so it is only what we currently believe the Oort cloud to look like. So Scholz's star was already at the inner edge of the cloud. I think a body massive enough to be a star out there would have been detected; the limit of the Sun's gravitational effect before the galactic gravitation takes precedence is what defines the limit of the Oort cloud. However something like Planet 10 is another matter (which neatly brings us back to the original thread!).

All in all I agree life _could_ have started in another star system but here I must apply Occam's Razor. Which is the more likely; that it evolved here or out there? Sure it is probably just as likely to evolve on another star as on Earth but I think the transfer is far far less likely. Which, of course, is not to say it's either impossible or didn't happen. But you must always keep in mind that life is just as likely to have evolved here as it is to have evolved in any close passing star system. So why is there so often so much resistance to the idea that it did so and this search for a frankly less likely solution?

As you say @Venusian Broon, life has to have managed to get into the other star system's Oort cloud/Kuiper belt first. And I'd venture to suggest that it's probably a lot harder to get out that far than to have come in from that far. Again, though, not impossible just less likely.


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