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

[SilentRoamer]

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?

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.

 

[Vertigo]

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....

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.

 

[Danny McG]

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

 

[Brian G Turner]

the double slit experiment

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

 

[Venusian Broon]

PHYSICS PEDANT INCOMING....

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:

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?

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!

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.

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.

 

[Vertigo]

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!

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.

 

[Vertigo]

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?]

 

[Brian G Turner]

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.

 

[Venusian Broon]

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!

 

[LordOfWizards]

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 = mc2 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?

 

[Venusian Broon]

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.

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

 

[Vertigo]

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...

 

[Venusian Broon]

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'...

 

[Vertigo]

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!

 

[Brian G Turner]

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]

 

[Vertigo]

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).

 

[Brian G Turner]

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.

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.

 

[Vertigo]

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!

 

[Dave]

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.

 

[Serendipity]

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