echi's dumb questions

No. The official scientific answer is "we have no f*ing idea what was before the big bang, so we don't even bother to guess.



Yes, that is exactly what it means. Space itself is expanding, so even if objects were not moving around in space (which of course, they are) they would still be have the distances between each other becoming greater.

Space itself is expanding...

How can it be said, then, that everything, even space, was present at the Big Bang? What's the difference between saying that "space is expanding" and saying that "more space is being created all the time"?

I think I disagree with this (note I am intentially couching my answer here).

I think that most cosmologists would answer with a large degree of certainty that there is no "before" the Big Bang. Time started with the Big Bang and therefore asking what happened before the big bang is like asking what the people living on Mars eat.

As some physicist said to a similar question (I don't remember who or why, but I remembered the quip because it struck me as funny); "There is no there there".

Other than having studied physics (and having dipped my toes in this subject) I don't feel qualified to give this answer without couching it.... but I am kind of sure I am giving the "official" scientific answer (by this I mean by the answer that is given by most real cosmologists).



When you are discussing these things, you should keep in mind that Cosmologists (and Physicists in general) base these ideas on Mathematics, and discuss these ideas in Mathematics.

When a Physicist says that space was "compressed" or "curved" or whatever, they are using the mathematical meanings of these terms. It is impossible for someone who has not mastered enough mathematics to understand the arguments these statements are based on.

Of course most people can understand the mathematics if they are willing to take the time to learn them-- but these arguments about the nature of space are very mathematical. Taking the English, dictionary definitions of these terms that scientists use to refer to mathematical concepts they have studied years to understand, inevitably leads to misunderstandings.

I sympathize. I'm told it's like trying to describe a symphony without resorting to notes and other musical notation.

Echi, I have found this website to be informative in helping me understand this stuff I've seen on PBS. Might help you too.

http://superstringtheory.com/cosmo/index.html

Thanks, all...

I checked out that link, b-fly.....pretty cool.

I'm guessing that the determination that space, itself, is expanding (as opposed to just more space being "created") is arrived at by observing the behavior of light and matter, which would be noticeably different if the expansion was due to something else. (How wrong am I?)

Okay. So, space is expanding. If we run the numbers in reverse we get a convergence of everything...including space. But how small, how compressed could it have been? Does the science hit a wall at the quantum level? Could there possibly be anything smaller? (I'm thinking, "yes".)

I'm not sure what you mean when you say new space being created. Do you mean, new space being created at the edges of an expanding boundary of the universe? If that is what you mean, then yes that is definitely wrong. We can observe no edge to the universe, and that wouldn't explain the fact that all celestial bodies are receeding from each other.

Unfortunately, we cannot be exactly certain about the shape of the universe given the extremely limited knowledge we have. It is sort of like dropping an amoeba into the ocean and asking him what the shape of the universe is. He knows its wet, wet in all directions as far as he can see...can/should he generalize this assumption, and say that the universe is an infinite space of water?

This is basically the same question that scientists are faced with. There is a lot of pressure to come up with an answer, a theory, that people can believe in. It would be misleading to say that we have any kind of confidence whatsoever. To say that we do is, in my opinion, really a merging of science and religion...it is better to stick to the observable facts and let people draw what conclusions from this they may.

The most critical basic observed facts are as follows:
1) As far as we can tell, in every direction the universe has a uniform distribution of matter.
2) Everything is moving away from everything else.
3) The things that are farther away are also moving away faster then the things that are close.

Modern theories are based almost entirely on different possible explanations of these facts. First, the fact that everything appears to be uniform is shamelessly generalized into the assumption that the entire universe is homogeneous. If the entire universe is homogeneous, then the universe must either be infinite and open, or finite and closed. By infinite I mean that there is an infinite amount of matter. By closed I mean that if you travel in one direction long enough you will end up where you started.

For the case of infinite open, this is the flat universe model. Basically imagine an infinite flat sheet, onto which 3 more dimensions are superimposed. The sheet is expanding as well.

The other popular shape is a sphere. This seems to be by far the more popular theory. Instead of superimposing the dimensions onto a plane, superimpose them onto the surface of a sphere. Then explain expansion by saying that the radius of this sphere is increasing. It's called a hypersphere because its got more than 3 dimensions. Thus the matter is finite and its closed so you will come back to the same point if you travel in one direction. Also, according to this theory valid points are only on the surface of this sphere -- meaning if you were to arbitrarily pick coordinates for each dimension, most of these points would not be locations in the actual physical universe. Since every point is on the surface of this hypersphere, the center of mass point is somewhere inside the sphere, and that is invalid location...so technically according to this model there is no such thing as center of mass.

As for evidence of expansion, the only evidence comes from the observed red shifting of electromagnetic waves. No other kind of behavior. But, this is extremely reliable and we can be confident that it does accurately tell us that everything is moving apart.



Most people are comforted by picking an available hypothesis, believing it, and sticking to it. For the religious, it is "god made everything, there was nothing before god" for some cosmologists, it is "the big bang made everything, before the big bang there was nothing."

But that is not science, it is faith. I do not disagree that this may be a prevalent opinion of scientists. However, if you ask any of them why they believe, you will not get a good straight answer. If you look deeper you will discover that there really is no such evidence. The truly wise do not attempt to stretch evidence beyond the breaking point to make such ludicrous claims.

I have heard that before the Big Bang there was a previous Universe which ended in a "Big Crunch", with all time and space being compressed into that tiny point before exploding and starting the process all over again. In this sense, the universe undergoes the cycle of birth and death.

The big crunch theories were put to death when we realized that the expansion of space was accelerating.

Stuh,

You are greatly oversimplifying things by confusing folk understanding with science.

We know a lot more, and we have a lot more evidence for it than you imply. (We don't know even a small percentage of everything, but we have a good understanding with a decent amount of certainty about some things)

You are correct that science starts with observations... but it can go much further than this. The observations lead to hypotheses which lead to predictions. These predictions are then tested with more experiments and more observations. These are all based on increasingly complex mathematical models.

When there is enough evidence that a hypothesis (or mathematical model of how the Universe workks) is the only conceivable way to explain the observations it becomes a theory. The term "theory" in science means that is accepted as the only possible way to explain things by the scientific community.

Let's start about time. Our ideas about time are now governed by General Relativity. General Relativity is now is now accepted by the scientific community and it is very effective at explaining observations and making correct predictions about future observations.

In the mathematical model of the Universe based on General Relativity, time is (for the lack of a better) "relative" meaning that if two things happen... you and another observer will disagree about which happened first based on things like speed and mass-- and they will both be right from their frame of reference.

If two people will disagree about which of two events happen first... it makes discussions of the word "before" a bit problematic. The problem with your "before the Big Bang" idea is that since space would have to pass through a singularity, there is no way that the time of any event in the other Universe could be compared with any event of ours. Before and After and Same time have no meaning in this sense.

But my point is that there is a good deal of math and science behind the statements made by Cosmologists. There have been mathematical models proposed and tested, experiments done and analyzied, sattelites and telescopes launched, black holes and quasars predicted and found, background radiation measured, atomic clocks launched etc. etc. etc.

This is whole lot more than faith.No one is saying we know everything or that we are absolutely certain about anything.

But there is a whole lot of evidence backed by research and math and discussion. There are somethings that we (as a scientific community) are pretty damn sure about-- and with reason.

Specifically where?



Actually there are two kinds of scientific theories. You describe the formal, taught in science class, rigorous definition. Unfortunately many of the modern theories do not fit this model and yet still get the term "theory" for instance "string theory", or some of the other theories I have been mentioning, which are little more than wild guesses.



Mmm...and the Standard Model isn't?

Have you noticed that every piece of evidence for GR is equal evidence for a quantized theory of gravity? In other words, there is no evidence for GR other than that we have been able to concoct some predictable math for it.



You are confusing general relativity with special relativity, which nobody is contending.



Yes, indeed, and yet none of these experiments provide any evidence for GR over the graviton. So whats your point?



No...you're missing the point. There are many clashing theories which have the experts divided. These theories are not substantiated the same way that the more basic scientific theories are...which is why they should actually be considered only hypothesis.

The evidence just isnt there. I would argue that your belief at this point is faith based. You have faith that what they are telling you is right because it involves a lot of math, a lot of smart people ave worked on it, and spent a lot of time working on it...but when your belief extends beyond your personal comprehension, its faith.

reading along, with interest

Let me take the easy point to disprove first, then when I have time we can talk about the specifics.



I disagree with your definition of faith. I don't think that combining a trust with the experts in a field, with a basic understanding of how science works, amounts to "faith".

I always hate getting sucked into arguments about the meanings of words. But I want to point out there is a clear distinction between "relgious faith" and a scientifically informed trust of what the experts have discovered. I understand both from personal experience.

My training is in Physics, and although I am not an expert... I have studied the basics (GR and Quantum included) enough to understand the arguments the experts are making. I understand the mathematics enough to understand the arugments even though I don't the background or depth that people working in the field have.

But let's take another field.... Every so often I go to the doctor. He does certain tests and comes back with recommendations about LDH and HDH etc. I have almost no experience in biology, or medical science or anything dealing with the science of life. I certainly have no more than a passing understanding of what role LDH plays in my biology.

But I trust the doctor because I understand the science process, and the role medicine plays in our society and the concrete results medicine has played in increasing life expectancy and drastically decreasing the incidence of serious diseases.

My trust in my doctor... and in medical science in general is not the same as "faith". Even though I personally know very little about proteins or genetics or any of the specifics of the science, I still know it is science and I think this is an informed decision. I would certainly separate a trust in medical science from a "faith" in paranormal cures.

Likewise I will state that evolution is the scientifically correct explanation of the origin of species even though I am not an expert.... again because I understand the scientific community that supports this theory. It is impossible for anyone to master every field. This is why we have scientists and a scientific review process.

But let's get back to the physics, where I feel a bit comfortable as one with some training.

I don't want to argue certainty here. I am going to say that there is a lot more evidence for what Cosmologists state about the Universe than you are implying.

For example, you state that my point about the relativity of time is based on Special Relativity which you then state that "nobody" is contending. I think this means you agree that my point is valid.

But Special Relativity of course is a special case of General Relativity. Based on my (somewhat informed) understanding of General Relativity, saying what happens before the Big Bang doesn't make sense.

I couched my answer, but it is my belief that expert Cosmologists would agree with my statement-- although if one comes and answers directly, I would (after listening to the argument) probably accept her answer. If there is a general consensus with most Cosmologist that this is correct-- I would accept this as pretty darn certain.

I am pretty sure that most Cosmologists would say this... and I have good reason to think this from my training and other things I have read and heard. But I won't go any farther than this until I find a Cosmologist to ask.

Well, as you say yourself, the exact meaning of the word faith is an issue of language semantics which is not worth getting into. I don't think that "faith" necessarily implies that you have zero evidence whatsoever to base your belief on. I think that faith just means trust in the absence of concrete evidence. In this case, you have faith that concrete evidence exists for something...even though you have not seen that concrete evidence. I don't mean to imply that faith in this sense is unreasonable. If we didn't have faith, if we didn't make assumptions, we would be inept. But even though we may work with these faith based assumptions, I do not believe we should entirely forget what we are taking on faith, because we inevitably make some mistakes. But enough about faith.

I could not do what the professional mathematicians do for science. But that is not always necessary to critique their work...because the math is based on generalized assumptions, and the assumptions are based on observations. If one does not agree with the generalized assumptions based on the experimental observations, one also cannot trust the result of the math that uses those assumptions as initial conditions!!!

I do not disagree with the evidence, and I do not disagree with the math, and I do not disagree that the math works at making approximations...but I also recognize that

a) we do not have the complete picture, we do not have a grand unifying theory,

b) and many of the generalizations based on evidence I found downright absurd, and are assumptions that I would not be confident enough in to depend on to run my toaster over -- and that does not take any knowledge of math.

c) in this thread, the only ambiguities I have presented having little faith in are ones that divide the professional scientific community, and therefore you cannot use simple trust in the professionals. If all of the experts agreed, then perhaps your argument would hold more weight...but as it stands, you are arbitrarily picking some professionals to trust and some not to trust, and without having the personal knowledge, you just can't do that.

I understand that there are limits to what we can observe. But is it possible that energy exists that is "sub-quantum"? (Is this even a meaningful question?)
If there is sub-quantum energy/matter, although it would be invisible, would it not be capable of producing larger-scale, gravitational effects? If so, then:
A) could this account for dark matter?
B) could "sub-quantum" energy behave in such a way as to produce (larger-scale) gravitational effects that may account for the (perceived) different forces?

Although I have two degrees in Physics, a BS and an MS, this is pretty advanced stuff, and I am not remotely qualified to give very good answers to your question. If you get your idea of how scientists study this from newspapers and layman's magazines, you'll get an incorrect idea. I have, however, had an opportunity to question someone on exactly this subject who is very qualified, and, although there is certainly some description that can be given at an elementary level, it's basically impossible to give a good explanation at that level. By way of illustration, I am linking in a recent scientific paper discussing this general topic. You can see that the actual theories don't come very much out of mere discussion of laymen type concepts.

Here is one such link:

Article on Inflationary Cosmology

Thanks, Brandon.
I don't expect to be able to understand all of the mathematical proofs and reasonings, but I can't see why the basic concepts, at least, should be so difficult to discuss in a non-mathematical form. (Perhaps my stubborness is related to my ignorance!)

Some simplfied explanation can be given in non-mathematical form, but when they verify a theory by measuring the vacuum polarization, or measuring dipole anisotropy of the cosmic microwave background, it takes a lot of words to explain what that means and why it proves anything related to cosmology. The bottom line is that I can ask a surgeon a question about an operation I'm going to have, but often he will have no choice but to answer my question in baby-talk, because I'm simply not trained in the subject.

Okay. I see what you mean.

Do you think the idea of "sub-quantum" energy/matter is nonsense (or, at least, non-science)?