1. I have a question, but I strongly suspect that the answer to my question
is going to be that my understanding is not correct. So I will pre-empt this
objection by first making sure that my understanding is correct.

My Understanding Is:
In mathematics, a guess is called a conjecture or a hypothesis depending
on how likely we feel the guess is to be true; so we have the Taniyama-
Shimura Conjecture, and the Riemann Hypothesis. When a guess is
proven to be true it is called a theory or a theorem; so we have Tunnell's
Theorem, Fermat's Little Theorem, etc. which are things that maths has
proven to be true.

In Science, a guess is called a theory, and if we can prove it is true it is
elevated to the level of a Law; so we have Newton's Laws of motion, but
Einstein's Theory of Relativity. I do not say this in a derogatory way, and
am not implying that in science a theory is necessarily any less valid, I
simply point out the essential difference between those things we know
are true, and those things we think are true.

So in science a theory can be thought of as a model that helps us to
explain our observations of the real world. We might in time alter the
model to allow for new observations, or we might throw it away all
together and replace it with a new theory. But, and this is important, a
theory is not necessarily supposed to be an exact representation of the
observation it is modelling; I can't believe that anyone thinks that
molecules actually look like those multi-coloured mobiles that hang from
science classrooms all over the world, they are just models to aid our
understanding.

My Understanding Is:
There is a fundamental question about the Universe concerning the fact
that it is observed to be homogeneous, at an electro-magnetic level,
despite the fact that parts of it are so far apart that they cannot possibly
have been in contact with each other at any time in the past. Stephen
Hawking has called this the electro-magnetic horizon paradox. Then in
1981 Alan Guth came up with a theory to explain this paradox. The theory
of inflation says that shortly after the big bang the universe went into a
phase of hyper-inflation that allowed parts of the universe to be further
apart than time and the speed of light would indicate they could be. Wind
the clock forward a quarter of a century and inflation is now widely
believed to be the answer to this fundamental question.

However, there is little if any direct evidence that inflation actually
happened; observations of the CMB are consistent with the idea of
inflation, but that doesn't mean it actually happened. There is also no
known mechanism that could have caused inflation to occur, no
conceivable experiment that can demonstrate that it occurred and not a
shred of evidence that it actually happened. Oh yes, the universe is flat, I
concede that much, and inflation would have turned a wrinkled universe
into a flat one, but that doesn't prove that inflation is the reason the
universe is flat.

If we can agree that what I have said above is fundamentally correct, I
will proceed to ask my question.

2.

3. I dont know who exactly is the person you're waiting for who has the authority to say they agree but I think what youve said is fairly reasonable!

4. Apologies for the delay but I can only do this at weekends.

So, from the complete lack of folks laughing their heads off at the first
part I proceed to ask you to consider Occam's Razor. This basically says
that when asked to choose between two competing hypotheses, choose
the simplest. Then we have:

Hypothesis 1.
An event that we can neither prove nor explain, nor provide a causative
for, occurred.

Hypothesis 2.
It didn't happen.

By this criteria the theory of inflation is a complete non-starter.

Now consider what I call the first rule for evidential reasoning.

Falsifiability. It must be possible to conceive of evidence that would prove
the claim false. The rule of falsifiability is essential for this reason: If
nothing conceivable could ever disprove the claim, then the evidence that
does exist would not matter; it would be pointless to even examine the
evidence, because the conclusion is already known - the claim is
invulnerable to any possible evidence. This would not mean, however,
that the claim is true; instead it would mean that the claim is meaningless.

Now it is possible for us to conceive of evidence that would prove the
theory of inflation false; that would be evidence in favour of some other
tenaciously to the theory of inflation it seems safe to conclude that the
evidence in favour of this alternative proposition is wanting. So we can
conceive of it, but it does not exist. So, at the moment, and in fact for the
last twenty-five years since Alan Guth came up with the idea, the claim
has been essentially un-falsifiable.

So my question is: Which part of science does this un-falsifiable theory
that fails even such a basic test as Occam's Razor; that has absolutely no
evidence in favour of it; for which there is no known mechanism that
could have caused it to happen, come from ?

It seems to me that the belief in this theory is about as rational as a belief
in God.

5. Originally Posted by numbers
So my question is: Which part of science does this un-falsifiable theory
that fails even such a basic test as Occam's Razor; that has absolutely no
evidence in favour of it; for which there is no known mechanism that
could have caused it to happen, come from ?
There are a couple things going on here...
First, inflation has the power to answer several questions that were unanswerable before - flatness, horizon, and monopoles. So it is powerful in that it resolves some key issues. If we discard inflation, we will still need to address these issues.

Second, there is evidence in favor of inflation. Specifically, when we compare what theory predicts with what WMAP observed, there is a striking resemblance. Basically WMAP provided strong evidence in favor of a flat universe and inflation. Any modern introductory astronomy text should provide a good overview with WMAP and theoretical prediction figures if you're curious.

Thirdly, there is a mechanism that can cause inflation. As the early universe expanded, it cooled. Around time when the universe was 10<sup>-35</sup> seconds old, theory predicts that the universe was cool enough that the GUT force decoupled into the electroweak and strong forces - releasing a tremendous amount of energy. What is meant by this "decoupling," is... well, Maxwell was able to show that electricity and magnetism were actually the same effect, and now we refer to it as electromagnetism. In the '60s, Weinberg, Salem, and Glashow showed that the E&M and the weak force could be unified in what we now call the electroweak force (they won the Nobel prize by the way...). A grand unified theory (GUT) is one where we can unify the electroweak force to the strong force - which hasn't been achieved yet. And if we can tie that to gravity, then we'd have a "theory of everything," which is what M-theory is trying to achieve. Anyway, at 10<sup>-35</sup> seconds is when theory predicts that the GUT decoupled into the electroweak and strong forces (with gravity having already decoupled around the Planck time, 10<sup>-44</sup> seconds) which would have released a tremendous amount of energy.

Lastly, I value Occam's razor, but there is another "razor" test - that of beauty. When a theory has a certain beauty to it, it leaves us with confidence that we're on the right track. Such is the case with inflation and M-theory.

Cheers,
william

6. Here is a link to WMAP:
http://map.gsfc.nasa.gov/index.html

And here you can find more info about how WMAP impacts the study of cosmology, the big bang, and inflation:
http://map.gsfc.nasa.gov/m_uni.html

This section mentions the predictions of inflation which can be tested.
http://map.gsfc.nasa.gov/m_uni/uni_101inflation.html

This site mentions how inflation can be tested but they don't use the actual data:
http://www.astro.ucla.edu/~wright/cosmo_04.htm

And what the heck... Wikipedia seems to have a nice write-up on inflation, so here that is:
http://en.wikipedia.org/wiki/Cosmic_inflation
you might notice the bit about how string theory may provide an alternative to inflation....

Here is a Sky & Telescope article which is pretty accessible:
http://skytonight.com/news/3311206.html?showAll=y&c=y

This and the links therein seem informational:
http://imagine.gsfc.nasa.gov/docs/fe...p_exhibit.html

(Still haven't found what I'm really looking for though...) :?

Yet more...
http://physicsweb.org/articles/world/19/5/5

This one is quite advanced... but if you ever wondered what it would be like at an astrophysics seminar, this is it. It appears to be a lecture given by a fellow from Oxford:
http://www.dark-cosmology.dk/worksho...kar/sarkar.pdf

(By the way, I'm not trying to overwhelm you guys with all this stuff, it's just that I can't find what I'm really looking for, and these seem too good to pass up....)

Oh well, I give up. But here is a powerpoint lecture given by Katie Freese from the University of Michigan. This has over 90 slides... usually it takes about a minute or so per slide, so this must have been one long talk! But it looks pretty good and I am familiar with her.
http://cosmo06.ucdavis.edu/talks/freese.ppt

Anyway, if nothing else, the two previous links should give the impression that these things are thought about to a great extent....

Cheers

7. Impressive couple of posts there william. 8)

8. Originally Posted by william
So it is powerful in that it resolves some key issues. If we discard inflation, we will still need to address these issues.
Then I respectfully suggest that science address those issues rather than side-step them with what is no more than a guess that is no more deserving of the title "Theory" than is my theory that the next car to pass my house will be red.

Originally Posted by william
Basically WMAP provided strong evidence in favor of a flat universe and inflation.

Originally Posted by numbers
Oh yes, the universe is flat, I concede that much, and inflation would have turned a wrinkled universe into a flat one, but that doesn't prove that inflation is the reason the universe is flat.
Assuming that the link exists is akin to the illogical assumption that because horses eat hay, and hay is missing from your meadow it must have been eaten by horses. The premise is true, but the conclusion is not the only one to follow from the premise.

In your third paragraph you attempt to provide a causative for inflation, and basically you say that it was caused by a force that would exist in a theory we do not yet have. Seems like a pretty tenuous and un-scientific explanation to me. I did find your mention of the cooling of the early universe very interesting but have so far failed to find a graph showing this cooling over time, the first five minutes, say. At one of your links I found this:

[Quote Starts Here] One second after the Big Bang, the temperature of the universe was roughly 10 billion degrees and was filled with a sea of neutrons, protons, electrons, anti-electrons (positrons), photons and neutrinos. As the universe cooled, the neutrons either decayed into protons and electrons or combined with protons to make deuterium (an isotope of hydrogen). During the first three minutes of the universe, most of the deuterium combined to make helium.[End Quote]

From which we can conclude that cooling sufficient for neutrons to combine with protons to make deuterium happened within the first three minutes. Can we get this down to a shorter timescale so that it impacts on the theory of inflation? Your post implies that cooling of the universe was a contributory factor to the initiation of inflation. But inflation kicked in at 10<sup>-35</sup> seconds. According to the above quote, less than a second later the temperature was 10 billion degrees. Does kind of beg the question: How hot was it before it cooled to 10 billion degrees?

As for beauty, I guess you already know you're on a hiding to nothing with that one, don't you. Can you define beauty, and has anyone proved a scientific link between beauty and truth?

We have a similar idea in maths; elegant and beautiful conjectures seem to turn out true more often than non-beautiful ones, and their proofs also have an inner beauty that I suspect a non-mathematician would be hard pressed to appreciate. The Riemann Hypothesis, for example, is a beautifull guess about the prime numbers, but we do have an awful lot of data to support the hypothesis whereas the data set for the theory of inflation is precisely one example which is not a lot to go on.

Thank you for your erudite and well-written response, but it has done nothing to make me change my views. The links are appreciated too, with some lovely pictures and graphs, but I see nothing in the nature of proof, and very very little in the nature of evidence. What there does seem to be a lot of is assumptions along the lines of "horses ate my hay" (see above).

9. I was tempted to leave this be... but I guess I'm more tempted to reply.

Originally Posted by numbers
Originally Posted by william
So it is powerful in that it resolves some key issues. If we discard inflation, we will still need to address these issues.
Then I respectfully suggest that science address those issues rather than side-step them with what is no more than a guess that is no more deserving of the title "Theory" than is my theory that the next car to pass my house will be red.
Inflation indeed addresses those issues. And inflation is more than just a "guess." Do a search using the keyword "inflation" on adsabs.harvard.edu and you'll see. If that doesn't work, then nothing will....

Originally Posted by william
Basically WMAP provided strong evidence in favor of a flat universe and inflation.

Originally Posted by numbers
Oh yes, the universe is flat, I concede that much, and inflation would have turned a wrinkled universe into a flat one, but that doesn't prove that inflation is the reason the universe is flat.
Assuming that the link exists is akin to the illogical assumption that because horses eat hay, and hay is missing from your meadow it must have been eaten by horses. The premise is true, but the conclusion is not the only one to follow from the premise.
Originally Posted by william
Basically WMAP provided strong evidence in favor of a flat universe and inflation.

Also, some of the links I provided should have made this much clearer. I probably can't make the case any better than they did, so you'll have to give them a read-through again.

In your third paragraph you attempt to provide a causative for inflation, and basically you say that it was caused by a force that would exist in a theory we do not yet have. Seems like a pretty tenuous and un-scientific explanation to me.
It is not that much of a stretch to think that the four forces were once one based on the success of combining E&M and electroweak. No working theory of a GUT or "theory of everything" is required to follow that line of reason.

I did find your mention of the cooling of the early universe very interesting but have so far failed to find a graph showing this cooling over time, the first five minutes, say. At one of your links I found this:

[Quote Starts Here] One second after the Big Bang, the temperature of the universe was roughly 10 billion degrees and was filled with a sea of neutrons, protons, electrons, anti-electrons (positrons), photons and neutrinos. As the universe cooled, the neutrons either decayed into protons and electrons or combined with protons to make deuterium (an isotope of hydrogen). During the first three minutes of the universe, most of the deuterium combined to make helium.[End Quote]

From which we can conclude that cooling sufficient for neutrons to combine with protons to make deuterium happened within the first three minutes. Can we get this down to a shorter timescale so that it impacts on the theory of inflation? Your post implies that cooling of the universe was a contributory factor to the initiation of inflation. But inflation kicked in at 10<sup>-35</sup> seconds. According to the above quote, less than a second later the temperature was 10 billion degrees. Does kind of beg the question: How hot was it before it cooled to 10 billion degrees?
The universe had to cool in order for neutrons to combine with protons to form deuterium. There is a critical temperature to where the gamma rays had so much energy that any nuclei that would form would soon be broken apart. You can relate a photon's energy to a temperature by comparing the radiation emitted from a black body at that temperature to the wavelength of the photon in question ala Wein's law.

If we were to measure the temperature of the universe at a time when it was 10 millionths of a second old, the temperature would be well over a trillion degrees (10<sup>12</sup> K). Before that, it is not that hard to imagine it being even hotter.

As for beauty, I guess you already know you're on a hiding to nothing with that one, don't you. Can you define beauty, and has anyone proved a scientific link between beauty and truth?
Elegance simply gives us confidence that we're on the right track. That's all.

We have a similar idea in maths; elegant and beautiful conjectures seem to turn out true more often than non-beautiful ones, and their proofs also have an inner beauty that I suspect a non-mathematician would be hard pressed to appreciate. The Riemann Hypothesis, for example, is a beautifull guess about the prime numbers, but we do have an awful lot of data to support the hypothesis whereas the data set for the theory of inflation is precisely one example which is not a lot to go on.
Not sure what you mean about your comment on inflation here. As I said before and provided links for, there is very good reason to think that inflation may be correct.

Thank you for your erudite and well-written response, but it has done nothing to make me change my views. The links are appreciated too, with some lovely pictures and graphs, but I see nothing in the nature of proof, and very very little in the nature of evidence. What there does seem to be a lot of is assumptions along the lines of "horses ate my hay" (see above).
You're welcome.
I had the hunch that your views wouldn't change. If you seek proof, then good luck (and you better stick with math). I think you're thinking too much like a mathematician in that they control the stock market on proof. In all other fields of science, proof is not as clear-cut. And... if you were thinking that I could prove inflation, then I'm sorry I disappointed you. I think the best anyone could do is say that observation hasn't ruled it out yet....

Cheers,
william

10. William,

Please don't give up on this thread because I have enjoyed researching the links you gave me and have collected some interesting stuff together, especially on this cooling thing. Based on the figures so far I have put a tentative graph together showing the temperature of the early universe but there is something not quite right about it. I need some time to properly formulate my questions but I think we are on to something.

I am not looking for proof, simply a clearer understanding of why an idea with such tenuous evidenciary support can be regarded as a theory.

Many thanks,

Numbers

11. When a person dreams up some idea, it should be accepted as valid, since its valid to that person.

When nobody else comes up with a better explanation, they join and play with same idea so it becomes a working theory.

Finally when all mankind can't find a way to disprove it becomes the Law.

Everything has a start point, why not accept something new as valid start theory to encourge at least some progress in any direction or dimension.

12. I counter things like the horizon paradox with a principle of probability called "The Law of Large Numbers."

It states that, if you roll enough dice, you get pretty much homogenous results on the big scale. IE. you could roll 3 6's out of 10 rolls, but you could never roll 300,000 6's out of a million rolls. Technically you *could*, but the odds against are astronomical.

I think there are enough separate dice being rolled in the formation of distant celestial objects that I don't think it should be too much of a surprise to see uniformity in their chemical compositions because, on that large a scale, random isn't really random.

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