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

[Ursa major]

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)?

 

[Brian G Turner]

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.

 

[Cathbad]

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

 

[Ursa major]

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.

 

[Dave]

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.

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.

 

[Vertigo]

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.

 

[mosaix]

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.

 

[Mirannan]

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.

 

[Vertigo]

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.

 

[Parson]

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?

 

[Vertigo]

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.

 

[Brian G Turner]

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?

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.

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!).

 

[Dave]

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.

 

[Mirannan]

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.

 

[SilentRoamer]

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.

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.

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.

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.

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.

 

[SilentRoamer]

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.

 

[Vertigo]

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.

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.

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.

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...

 

[Serendipity]

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.

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!

 

[Serendipity]

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

1. 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?
2. 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?]
3. 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.
4. 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....

 

[Brian G Turner]

Have split this discussion on physics into its own thread.