Why does the Steady State Theory not work?

[Outpost4]

Good points. Agreed, "only" was a bad choice of words on my part. I'll stand by my argument, though, with your caveat that skepticism should be practiced.

The Standard Model is out there, a sitting duck, waiting to be shot down. So far nobody has done it. Give it your best shot.

We should have this same discussion about creationism.

 

[FordSVT]

ancient said:
The multiverse theory is a stretch at best, imo. Sure there are some interesting observations and all, but ours is probably the only universe, imo. Other dimensions, maybe, but not independent planes.

Don't me so sure!

A new study confirms the possibility of multiple universes.

 

[Asbo Zaprudder]

FordSVT said:

ancient said:
The multiverse theory is a stretch at best, imo. Sure there are some interesting observations and all, but ours is probably the only universe, imo. Other dimensions, maybe, but not independent planes.

Don't me so sure!

A new study confirms the possibility of multiple universes.

Many non-technical objections to parallel universes are based on the dubious meme of "the uniqueness of the self" compounded by that other, almost as dubious, meme "the existence of the self".

 

[Newtype_A]

Summed it up nicely, Geoff. I do suggest that the "tired light" phenomenon would probably have something to do with an unknown factor of gravity we don't understand yet (and there's SO much about gravity we don't understand). More research into how gravity functions at extra-galactic distances would probably shed some light on the matter.

I personally expect that we will find gravity is active at a much greater distance and at greater intensities than Relativity predicts, since that would seem to fit the largest number of observations IMO.

 

[iguana_tonante]

Whoa! I've been away for a while from the computer and the discussion really raised its stakes scientifically!

I'm sorry I let Outpost4 all alone defending the Big Bang Theory: I never meant to let you do all the work, mate!

Outpost4 said:
Good points. Agreed, "only" was a bad choice of words on my part. I'll stand by my argument, though, with your caveat that skepticism should be practiced.

The Standard Model is out there, a sitting duck, waiting to be shot down. So far nobody has done it. Give it your best shot.

I have to agree. There are some theories that could challenge the Standard Cosmological Model (on logical ground or by appeal to simplicity), and I readyly admit that I am not knowledgeable enough to dispel every single doubt about the Big Bang.

But (and it is a pretty big but ), there are very convincing reasons (both theoretical and practical) why the Standard Cosmological Model has reached a consensus of sort by the scientific community. I do not know them all, but I know that there are some people a lot smarter than me that find that solution pretty satisfactory, even if they are working to refine it to a degree. I am fully conscious that this is dangerously close to an appeal to autority, but today science is such a complex and vast field that it is impossible to be knowledgeable on it all. So, in matters that are not really my subject of research, I usually bow to conventional wisdom, since I know I'm not really able to confute their argument.

Maybe they are pulling my leg, but without this kind of collaborative approach, science is simply impossible to practice nowadays. If I were to find a better theory than the Big Bang (better meaning,"more capable of explaining observational evidences") I will be extatic. Unfortunately, I do not really think I will. If you can do it, please by all means be my guest and present it to the next conference meeting. I will be the first to cheer. But I have this feeling that much of the challenge I saw against the Big Bang theory is due more to the difficulty and counter-intuitiveness (is that a word?) of the subject than to contrary evidences.

I know it is a pain in the ass, but much of today's cosmology relies on advanced mathematics that I can barely understand and that can't be correctly conveied in a internet forum. If you are really interested in cosmology, I suggest you to pay a visit to a nearby college or astronomical observatory, where often there are classes and seminars about this subjects. Maybe they can explain things better than me, and offer you the full mathematical know-how that you need to fully treat this kind of subject.

 

[chrisspringob]

Newtype_A said:
I prefer to apply Occam's Razor: all things being equal, the simplest explanation must be the truth.

It seems to me (though I may be biased, or just too stupid to know better) that the premise "the Universe is expanding" creates more questions than it answers, and requires an ever increasing number of elements in order to be made consistent. Conversely, the premise "the wavelength of light shifts frequency over intergalactic distances" leaves only one un-answered question: HOW?

Given this, I think the steady-state theory could still be viable, at least insofar as it has the fewer number of unknowns and requires a smaller number of unnecessary elements to be discerned.

There are loads of reasons why the Big Bang matches the evidence better than Steady State + Tired Light theory. First of all, the Steady State Theory does *not* mean that the universe is static. In most versions of Steady State, the universe *is* expanding, but there's new matter being created, so the density of the universe never drops down to zero, and the process can go on indefinitely. See this explanation:

http://en.wikipedia.org/wiki/Steady_state_theory

The thing is, the universe should either be expanding or contracting. It should be contracting because of gravity, but if there's some force pulling it apart, then that could hypothetically be enough to more than offset the gravity. Now sure, it's possible that there's a repulsive force that's *exactly* strong enough to counteract gravity and keep things exactly static without expanding or contracting, but that seems kind of contrived to me.

Anyway, here are some good observational reasons for why the Big Bang works:

http://en.wikipedia.org/wiki/Big_Bang#Observational_evidence

and why Tired Light doesn't:

http://www.astro.ucla.edu/~wright/tiredlit.htm

Just to name a few, The Big Bang offers an explanation for the existence of the CMB, and it's hard to see how you could explain that if the universe was static. The Big Bang also explains the observed abundance of light elements pretty well, and it explains why we don't see any stars older than ~13 billion years. People have also done N-body simulations to model large scale structure formation in Big Bang cosmology, and it looks pretty much like what we observe. There's no plausible explanation for why the large scale structure of the universe would look like that if the universe had been around forever. Also, how do you explain things like why distant galaxies (meaning, galaxies for which we're now seeing what they were like many billions of years ago) are fundamentally different from the galaxies in the present epoch which we see nearby, in terms of their abundance of heavy elements and how blue or red the stars are? Why would galaxies be evolving like that if the universe has been around forever?

Also, if the universe was static, that still wouldn't explain away dark matter, because you still need dark matter to explain how galaxies can rotate as fast as they do without flying apart. In fact, I'd like to defend dark matter against accusations that it's something bizarre that requires a contrived explanation.

There's nothing that weird about dark matter. All you have to accept is that there are particles that only interact with other matter gravitationally, and that these particles make up the majority of the mass in the universe. Why is that so strange? There's nothing weird about that. We can map this stuff on large scales with a variety of techniques, and it appears to behave exactly like regular matter, it's just that we can't actually "see" it directly, because it only interacts with other matter via gravity. I don't think that's actually all that strange. It makes more sense than the alternatives (IMHO).

Dark energy, OTOH, is pretty strange, and there's no good explanation for it. But the BB Theory explains so many other things that I don't think we should throw it out just because we're currently having difficulty explaining why the expansion of the universe has slowed down and sped up in the manner that it has.

 

[Balthier the Great]

There's nothing that weird about dark matter. All you have to accept is that there are particles that only interact with other matter gravitationally, and that these particles make up the majority of the mass in the universe. Why is that so strange? There's nothing weird about that. We can map this stuff on large scales with a variety of techniques, and it appears to behave exactly like regular matter, it's just that we can't actually "see" it directly, because it only interacts with other matter via gravity. I don't think that's actually all that strange. It makes more sense than the alternatives (IMHO).

Well, there's no problem with it other than that we can't find it, and have no idea what it looks like. And because we don't know what it looks like, a test for its existance doesn't seem to be workable.

What we can actually say based on our observations is that the galaxies should be flying apart, and they aren't. That's all the evidence says.

Dark matter does require a few hoops. Like the fact that every other type of matter is made of atoms that can interact with each other via electrical, nuclear and other forces. Unless I'm missing something, atoms are the only stable type of matter, so what is DM made of? What is Dark Matter, exactly? If it's a real substance, it must have properties that we can describe accurately.

I think that what we're discribing as Dark Matter may well be some poorly understood property of gravity or matter itself. It makes more sense than starting to posit energies and matters that we have no reason to believe in.

 

[chrisspringob]

Well, I'm not sure what you mean by "energies and matters that we have no reason to believe in" or even "a test for its existance doesn't seem to be workable". There's plenty of evidence in favor of dark matter existing. (This is not to say that it's a settled question. Just that there's evidence in favor of it.) Zwicky first observed the fact that there didn't seem to be enough stars in galaxies to explain how fast they rotate. From there, there was the hypothesis of dark matter, and, based on various pieces of observational evidence over the years, all kinds of predictions for observational effects that we should be able to see if dark matter does in fact exist. So far, all of those observational effects have indeed panned out, and there are lots of things that dark matter can help explain, from the shape of large scale structure in the universe, to the shape of the CMB anisotropy spectrum, to the velocity dispersion of galaxy clusters (I'm glossing over various caveats and complications there, but the basic point stands).

Then there are things like observations of gravitational lensing, and the observed galaxy rotation curves, which show matter density profiles of galaxies that seem to match just what we would expect if the galaxies contained large halos of a kind of matter that only interacted with itself and other matter through gravity. These would seem to be pretty strong lines of evidence. Granted, it's possible that there's some form of modified gravity that explains it all, but IMHO, in this case, Occam's Razor argues in favor of the idea that there's some matter that only interacts with other matter gravitationally (dark matter), but it obeys the laws of gravitation and GR as we've come to know them, rather than saying that gravity operates differently on large scales (as you would under a modified gravity theory). Sure, we can't "see" the dark matter directly, but we can't see black holes either. That doesn't mean that there isn't any evidence in favor of their existence.

But anyway, if you think modified gravity makes more sense, I won't object. I just don't think it's as likely, given what I know about the issue. Anyway, this is just an aside from the main point of my earlier post, which was that even with Steady State and/or Tired Light theories, you still have to have either dark matter or modified gravity, as there are all kinds of observations that lead you in that direction, that are unrelated to the Big Bang.