Happy Atheist Forum

Interesting article on the BBC site. (http://www.bbc.co.uk/news/science-environment-11030889)

It is kind of eerie to think that in a few trillion years, there will be nothing other than black holes and red dwarfs floating about the cosmos.

Quote from: "karadan"It is kind of eerie to think that in a few trillion years, there will be nothing other than black holes and red dwarfs floating about the cosmos.

I was aware that this outcome was possible. "Eerie" is perhaps the most appropriate word to use.

Probably best we leave the universe.  

Quote from: "Dretlin"

Quote from: "karadan"It is kind of eerie to think that in a few trillion years, there will be nothing other than black holes and red dwarfs floating about the cosmos.

I was aware that this outcome was possible. "Eerie" is perhaps the most appropriate word to use.

Probably best we leave the universe.  :hmm:  Where would we go?

Interesting link.

However, Dark Energy and Dark Matter are still just 'place holder' names for as yet undefined forces or apparent space time distortions. There is still the issue of Quantum Gravity to be solved and until that and the 'Standard Model' are unified the one thing we do know for sure is that we don't know everything.

Quote from: "Tank"

Quote from: "Dretlin"

Quote from: "karadan"It is kind of eerie to think that in a few trillion years, there will be nothing other than black holes and red dwarfs floating about the cosmos.

I was aware that this outcome was possible. "Eerie" is perhaps the most appropriate word to use.

Probably best we leave the universe.  :hmm:  Where would we go?

Other, younger universes of course! Duh  :D

Quote from: "Tank":hmm:

I wonder if this model will hold up in the future.

Quote from: "Dretlin"

Quote from: "Tank":hmm:

I wonder if this model will hold up in the future.

Exactly my point. They may well be right in their observations but as some of the apparent causes of those observations are currently not 100% watertight then there may be 'wriggle room' later when somebody does have a 'Eureka' moment and figures out the real relationship between Quantum Gravity and the Standard Model.

are there any competing interpretations of this data?

Quote from: "humblesmurph"are there any competing interpretations of this data?

I am unsure, though I will look and would encourage anyone to share it if they find it.

They are placeholders for 'we don't know yet' in precisely the same way as gravity is. They are descriptions of effects. What the cause is of those effects is not yet known, in all three cases, but the effects are real and observable. There's no mystery here. In the case of, for example, dark energy, we know that the expansion of the cosmos is undergoing acceleration, which is an effect that needs to be accounted for, so they came up with energy that can account for it, but of course we haven't actually observed this energy, only it's effect. Again, the same is true of gravity. We don't know what causes gravity, but we know it exists.

QuoteIt will eventually become a cold, dead wasteland, researchers say.

Like Russia?

It's all going down the drain... Welcome to MY world  

Our universe does have to end one day - if not for one reason, than the other. However, I think it might just be that in the cosmic dust of our universe, a new universe will be born. Without humans in it, but not being a fan of our species, I don't see it as a bad thing.

Quote from: "hackenslash"They are placeholders for 'we don't know yet' in precisely the same way as gravity is. They are descriptions of effects. What the cause is of those effects is not yet known, in all three cases, but the effects are real and observable. There's no mystery here. In the case of, for example, dark energy, we know that the expansion of the cosmos is undergoing acceleration, which is an effect that needs to be accounted for, so they came up with energy that can account for it, but of course we haven't actually observed this energy, only it's effect. Again, the same is true of gravity. We don't know what causes gravity, but we know it exists.

Good point. Although would I be right in saying we have a better understanding of the effects of gravity than that or DM & DE?

Quote from: "humblesmurph"are there any competing interpretations of this data?

I have not seen any and as it is a recent study and release of data it will be a while before we do see any reasoned criticism as opposed speculative comment.

Quote from: "Tank"Good point. Although would I be right in saying we have a better understanding of the effects of gravity than that or DM & DE?

Not precisely. It's a bit of a thorny problem, TBH. The fact is that DM and DE may well represent how poorly we understand gravity.

Dark matter is postulated because, given our understanding of gravity, there isn't enough detectable mass in the universe to keep it all hanging together without flying apart. This actually includes gravitationally bound entities such as galaxies, which simply must contain more mass then can be observed to remain gravitationally bound.

Dark energy is postulated because recent observations demonstrate that cosmic expansion is actually accelerating, which means it's overcoming the gravitational attraction present in the cosmos. That's why it's being touted as a 'cosmological constant', the idea being that the influence of dark energy was there from the beginning, but that until expansion reached a certain phase, its effect was damped by gravitational attraction. As the expansion passed this phase, DE could reassert its influence and cause expansion to accelerate. It seems like an additional entity, which is why the credulous jump on it as something that we have faith in while not being able to see it, but it's quite parsimonious at bottom, because something is causing expansion to accelerate.

In short, DM and DE represent a better understanding of gravity than we had previously, and are actually functional in gravitational terms. The only thing is, we don't actually know why. In reality, DM and DE, when treated as separate from gravity (which is always going to be problematic, precisely because they are a description of effects related to gravity in one way or another), are precisely as well understood as gravity. We can measure and describe their effects quite precisely, but we don't actually have the faintest idea of what they actually are. We can say how gravitationally bound objects should behave with the mass they are observed to contain, and we can measure how much our observations diverge from those predictions. This represents a measurable understanding of dark matter. We can also say that we understand how cosmic expansion should proceed under our understanding of gravity, and we can measure the divergence from those predictions. This represents a measurable understanding

One caveat is this: If Einstein was correct, then we at least have some picture of gravity as the warping of spacetime, but we have no clue about what causes that warping, so we're pretty much where we were before. It also isn't absolutely clear that Einstein was correct in this regard, and we won't know much more until some serious experiments are carried out, some of which are scheduled for the LHC when it gets to doing physics at full chat. If the Higgs-Boson is discovered, then we have the Higgs field, which will give us a mechanism for the warping of spacetime, and it is actually the warping itself that imparts mass in this model. Then, of course, we have the graviton, which would actually make gravity a force, because this is a force-carrying particle, akin to the photon.

It may also be that M-Theory is on the right track. This gets a little more complicated.

A good book that deals with a lot of this in quite accessible terms is Brian Greene's fabulous Fabric of the Cosmo. He also deals with some of the ideas arising from M-Theory (this is actually his own field, so it gets a fair bit of the airtime in his book). One thing I will say about the book is that it's important not to get too hung up on his treatment of entropy which, being laid out in terms for the layman, is less than rigorous. He, like many popular science authors, treats entropy as disorder, and doesn't really deal with it in a manner that makes it clear precisely why entropy is most readily described as disorder, while not actually being disorder. I found myself screaming at the pages on occasion, because his treatment is actually quite misleading.

Anyhoo, I hope that clears some of it up. I had intended this post to be quite terse, but got carried away somewhat. :lol:

Thanks for that most interesting and enlightening post Hack. I will have a look at the book recommendation.

As you point out discovering the mechanisms that underpin gravity/DM/DE would be a remarkable step forward and hopefully the LHC will shed light on these mechanisms.

Quote from: "hackenslash"Lots of awesome

 :hail:

Okay everybody, we have a few trillion years to figure out how to stop heat death.

And... go!

Eh... Only took us a... Vell, very short time to figure out how to stop life, so how hard can it be?! We just... Just... Errm... ..! Build the opposite of a gun and shoot dead people with it!  

No, no, heat death (http://en.wikipedia.org/wiki/Heat_death_of_the_universe). The theory is, eventually, the universe will reach maximum entropy. We've gotta stop it because the universe will become uninhabitable. Maybe we can trigger the big crunch.

Quote from: "Will"No, no, heat death (http://en.wikipedia.org/wiki/Heat_death_of_the_universe). The theory is, eventually, the universe will reach maximum entropy. We've gotta stop it because the universe will become uninhabitable. Maybe we can trigger the big crunch.

Uninhabitable, eh..? Well, we'll just have to make the opposite of the mother of all destructions  

I remember reading a time line of the heat death of the universe.  It is discomforting.  We think of existence as infinite, but there is an end point and it will be reached because the universe has all the time it needs to settle down and die.

Well, if any force in this universe can stop the heat death, I guarantee you it's the human race. I think the human race or whatever we will have become over time will be more than capable of doing so, I sincerely doubt we will reach any cataclysmic disaster if one does not happen in the next decade or so because by then the human race may become impossible to extinguish thanks to our technology. I believe there is merit to the law of accelerating returns and I am a transhumanist, I believe the singularity will come sometime in this century. I can't even imagine what we will be like in over a few trillion years but the human race will surely dwarf any "god" we thought up in the past or present. SCIENCE FTW!

I think you're overestimating the abilities of humans. Our influence on the universe is piddling, and will almost certainly remain so. More importantly, decrease in entropy requires the input of energy, and is therefore only achievable on a local level. The input of energy at a local level necessarily increases entropy overall. Every time we do work of any kind, we make energy unavailable to do work, which is the definition of entropy. What this means for our ability to reverse heat death is simple. We can't.

We might be able to escape heat death by jumping to younger universes, though.

Sure. I am overestimating humans if we're thinking of them in terms of the standard Homo Sapien. I'm thinking of creatures one with their own technology completely erasing the line between their biology and technology. The majority of the population thinking with all the ambition and creativity of the human race but with the ever rapidly evolving computational power and perfection of a machine. New theories we've never thought of or wouldn't think of because of math beyond our brain's capabilities to process quickly or comprehend much at all will become child's play as we run equations through our heads millions of times every second.

Although I would imagine that we may sooner figure out how to leave our universe before we can actually stop it's expansion but you never say never, physics isn't absolute, considering the phrase dark matter is just a place holder who knows what we will eventually learn about the universe. in a couple of years we could have to rewrite everything we know about physics.

As soon as AI starts upgrading itself to the point of Matrioshka brain status, anything and everything will be possible. Links between universes will be a walk in the park
By that point humans will live their lives as pure energy anyway.

Just a couple of points, in the interest of a little rigour.

Quote from: "Ultima22689"Sure. I am overestimating humans if we're thinking of them in terms of the standard Homo Sapien. I'm thinking of creatures one with their own technology completely erasing the line between their biology and technology. The majority of the population thinking with all the ambition and creativity of the human race but with the ever rapidly evolving computational power and perfection of a machine.

This is wishful thinking, to be honest. Even given huge technological mastery, the sheer scale of the cosmos is an issue.

QuoteNew theories we've never thought of or wouldn't think of because of math beyond our brain's capabilities to process quickly or comprehend much at all will become child's play as we run equations through our heads millions of times every second.

This is a misunderstanding of the possible future capabilities of the human brain, and I think it seriously doubtful that we will evolve much more capacity than we already have. It may certainly be possible to have  neural implants, increasing our capacity, but there are physical limitations to how large our brains can grow naturally. More imortantly, though, it isn't clear that the kind of neural implants we're talking about are even possible, for all sorts of reasons, not least the simple fact that all our brains are wired completely differently. If your brain were downloaded and implanted into mine, it would make absolutely no sense, because your synaptic connections are all radically different from mine. I'm not ruling it out, but it's important to be aware of the limitations.

QuoteAlthough I would imagine that we may sooner figure out how to leave our universe before we can actually stop it's expansion but you never say never,

ACtually, I can, although I suspect that this is simply a non-rigorous use of the word 'universe'. There is no way to leace the universe, because there is no outside the universe. The universe is literally all that exists. Of course, it may be that you are employing the word in the sense of that which arose from the big bang, in which case, I refer you to my earlier comments about our cosmos being a closed system.

Quotephysics isn't absolute, considering the phrase dark matter is just a place holder who knows what we will eventually learn about the universe. in a couple of years we could have to rewrite everything we know about physics.

That's doubtful. Rewriting everything we know about physics would require that we've missed something fundamental. Our current physical theories are immensely accurate, so they are definitely giving us the right picture. The picture is incomplete at the moment, but our best theories are definitely right. The two remaining questions in physics that really matter are the unification of General Relativty and Quantum Mechanics (or answering the question of why they may not be unified) and describing what gravity actually is. These two questions can actually be stated to be one and the same. If we discover the graviton or the Higgs particle, then both questions are answered and we can work toward a quantum theory of gravity, which is really the last piece in the puzzle. All areas in physics, whether relativistic mechanics, quantum mechanics or particle physics, are all geared toward fitting this final piece into the puzzle. Much of the rest will be, I suspect, mopping up the details.

As for the comment about dark matter being a place holder, this doesn't mean that there's something fundamental that we've missed, or that there is something missing from our theories. It just means that there is matter out there that doesn't reflect or emit radiomagnetic energy. There's nothing exotic about it, we just can't see it.

As Professor Farnsworth said: "Evacuate the Universe!"

Quote from: "karadan"It is kind of eerie to think that in a few trillion years, there will be nothing other than black holes and red dwarfs floating about the cosmos.

It's all about perspective. Is it not more eerie to think in just a few decades there will be nothing, as far as we care, in the universe? There you go a much more depressing thought. The univese is practically timeless compared to eyeblick we exist through. The universe wll continue to exist long after heat deat,h it will just be alot more boring.

Quote from: "Will"No, no, heat death (http://en.wikipedia.org/wiki/Heat_death_of_the_universe). The theory is, eventually, the universe will reach maximum entropy. We've gotta stop it because the universe will become uninhabitable. Maybe we can trigger the big crunch.

I'd skipped this post, but it does require a response.

Maximum entropy is a very tricky proposition to deal with. Bear in mind that, in the classical big bang model (which is not established by any stretch of the imagination), our cosmic expansion began as an super-dense, super-hot point. In this model, the cosmos was at maximum entropy before the expansion began. The expansion, however, changes the game, because it increases the maximum value that entropy can reach.

In the 'heat death' scenario, what actually happens is that a maximum in thermodynamic entropy is reached, by attaining thermal equilibrium. What this means is, essentially, that the entire cosmos becomes the same temperature. At this point, all thermodynamic processes stop. This is problematic for several reasons. Firstly, the expansion will continue, which means that the maximum attainable value for entropy will continue to increase, which seems to contradict the idea of reaching maximum entropy. Further, gravity will still be in play, albeit reduced in influence massively as the expansion continues and bodies become more disparate.

As for triggering the big crunch, that idea has been dead in the water for some considerable time, since it was discovered that cosmic expansion is increasing. The best model we have at the moment is that the cosmos will continue to expand indefinitely, and eventually all matter will decay into a sea of photons. After that, who knows? It may be that at this point, another quantum fluctuation will trigger the next cycle. Maybe the world-branes will collide, triggering another phase of expansion. There are a few model on the table, and which, is any, are correct remains to be seen. I'm actually quite excited, because we live in the greatest era of discovery since the dawn of man, which is pretty incredible, given what we've already discovered. Perhaps the LHC will provide some answers. What the GWD experiments will almost certainly provide, if not the answers themselves, is a better idea of what the final answers will look like, and what features they must have.

I'm actually quite hopeful that, in the lifetimes of some of the members here, we will finally have a quantum theory of gravity. At that point, most of physics will be concerned with dotting the 'i's and crossing the 't's. Of course, they said the same just before the discovery of Special and General Realtivity, and Quantum Mechanics. Maybe the answers that are provided in the next century will only open up more questions. I certainly hope so because, while it is nice to have answers, it's much nicer to have questions, because questions drive knowledge forward.

/waits for one of our bible bunnies to exclaim "AH HA! See that is proof that God is there! You don't know what it is, it MUST be God! Praise the Lord!"

I'm not educated in physics or astronomy whatsoever...but couldn't all the mass we're missing be black holes that aren't in galaxies, and therefore invisible to us?  How could we possibly know how much mass should be in the universe?

AH HA! See that is proof that God is there! You don't know what it is, it MUST be God! Praise the Lord!

Quote from: "AnimatedDirt"AH HA! See that is proof that God is there! You don't know what it is, it MUST be God! Praise the Lord!

Quote from: "DropLogic"I'm not educated in physics or astronomy whatsoever...but couldn't all the mass we're missing be black holes that aren't in galaxies, and therefore invisible to us?

No, Read the post about dark matter/energy above, and it is all explained. Galaxies hold together too well to be accounted for by the mass contained within them.

QuoteHow could we possibly know how much mass should be in the universe?

By how it behaves.