The Big Bang Theory - How Sure Are We?

[back-marker]

Please excuse me if this seems like a really ignorant question. :)

I understand the basics behind the big bang theory but I am having trouble figuring out how sure we are of it. In comparison to lets say evolution, how does it compare? I would rank evolution at 100% sure. What is the scientific consensus on the Big Bang?

[ngeo]

Ah, the innocence of youth!

You might notice there are 192 pages of threads in this section, back-marker, and most of them are about this very subject. This being the ATM section, I would say there is no consensus here. I would call the "Big Bang" (being informed that it is a "meta-theory", a theory about theories) educated speculation.

[back-marker]

Gotcha. Just realized this is the section is to bring up other ideas. Silly me.
How about mainstream science? What do they think?

[ngeo]

After a few years of observing them, I would say that in the public pronouncements of mainstream scientists and research institutions, the "Big Bang" has the reputation of accepted fact with some loose ends like Dark Energy and Dark Matter that need to be tied up. That might be difficult. Also the "Big Bang" is intimately tied up with the standard model of particle physics, which is missing one particle, the Higgs Boson. That particle has yet to be located but the Large Hadron Collider now ready to operate in Europe should determine its location if any.

But (again, my own observations) among physicists there is always doubt, and to say "Big Bang" is to say only that the universe is expanding. Since they like to extrapolate backwards, that means at some point it was very small, dense, and hot. If you keep going back, you end up with a singularity, but you have to be careful with these scientists. The singularity is not part of the "theory"! But they seem pretty fixated on a particular age for the universe of around 14 billion years because the complex mathematics around which they operate seems to require it.

There is a lot of sweat equity in the Big Bang, and I think there is a lot of sweat ahead for the mainstream.

[Gillianren]

Welcome. I'm not a scientist, but I understand current mainstream scientific certainty for the Big Bang to be about 75% or higher, given evolution at 100%. Of course, it could be wrong, but whatever replaces it will have to answer more, and no idea I've seen presented seems likely to do so.

Maybe a moderator will kindly move this into Q&A or General Science?

[back-marker]

Thanks for the answers. I had read about the lose ends and stuff. That's what prompted me to asks the questions. I was previously under the impression that we were as sure about it as we are about evolution. Well perhaps not as sure but close to it.

Science needs to come up with other words that form better distinctions as to what stage a theory is at. Would avoid a lot of confusion with the general public. Perhaps call it a proof or something when we are sure the theory is correct.

Btw, the LHC wont really be in operation until 2008. It will be turned on in Nov of this year last I checked.

[RobA]

After a few years of observing them, I would say that in the public pronouncements of mainstream scientists and research institutions, the "Big Bang" has the reputation of accepted fact with some loose ends like Dark Energy and Dark Matter that need to be tied up. That might be difficult.

It's also important to note that Dark Energy and Dark Matter are not requirements of the Big Bang. The BB was around WAY before these were discovered - and discovered is the operative word.

Although we don't know what DM and DE are, the evidence for them came in totally independently of the BB. All cosmological theories had to be made to accomodate them.

The fact that the BB accomodates them as well as it does - including DM/DE's effect on the CMBR - is (IMHO) strong support for the theory.

[Nereid]

Moved, from ATM section to Q&A ...

Welcome to BAUT, back-marker! :)

[Ken G]

Interpreted broadly as meaning that the universe is expanding, I'd say the odds are higher than 99%. In short, I would accept 100 to 1 odds against my children's inheritance that this view will not be supplanted in my lifetime. What will happen with DM/DE I cannot guess, but I'd take 3 to 1 odds on DM and even odds on DE.

[Jeff Root]

To add one more voice, it doesn't seem possible that the
observed redshift of distant galaxies can be explained in any
other way than as a Doppler shift, with speed proportional
to distance. That means everything is moving apart. Which
in turn means that everything was once close together.
Beyond those near-certainties you start to get scope for
reasonable disagreement. The closer to the initial moment
of creation, the greater the likelyhood of disagreement.

-- Jeff, in Minneapolis

[antoniseb]

In the same way that Evolution had the right overall picture when Darwin first proposed it, but that the specific mechanisms for evolution are still being discovered and detailed, the Big Bang overall seems pretty certain, but the details of how it is expanding depend on understanding some physics that hasn't been made clear yet.

[Cougar]

I would call the "Big Bang"... educated speculation.
That would be a horribly wrong mischaracterization. As made clear by Chris Hillman on UCI's John Baez website.... (http://math.ucr.edu/home/baez/RelWWW/wrong.html#bang)

"[T]he idea of a beginning (particularly a violent beginning) to the Universe seems to trouble many nonscientists (and even some scientists). Ironically, it is possible that if more people understood what cosmologists really believe they know about the early universe, the standard Hot Big Bang theory would not attract so much psuedoscientific "critiques". Let there be no mistake--- the standard Hot Big Bang theory is scientifically speaking about as secure as the theory of evolution by natural selection. But this theory does not say what many noncosmologists think it does--- the real theory makes far less grandiose claims than bad popularizations tend to suggest, and at the same time, is far better supported by a tremendous body of interlocking chains of evidence than most people realize."

As explained here.... (http://www.damtp.cam.ac.uk/user/gr/public/bb_pillars.html)

"The four key observational successes of the standard Hot Big Bang model are the following:


Expansion of the Universe
Origin of the cosmic background radiation
Nucleosynthesis of the light elements
Formation of galaxies and large-scale structure
The Big Bang model makes accurate and scientifically testable hypotheses in each of these areas and the remarkable agreement with the observational data gives us considerable confidence in the model."
So I'm with Ken G in his estimate about how sure we are about this theory. Of course, as with ANY scientific theory, the door is ALWAYS left open a crack to allow for future observations. And the big bang theory has become a very large, interlocking web of evidence and independent verifications. We may get a biased view of the entire theory because the most "interesting" parts are those that are at the cutting edge of the theory where there is research in progress. As Antoniseb indicates, there are many finer details being worked out, and of course the proposed answers to the cutting edge details are much less secure then the fundamentals of the theory.

[Spaceman Spiff]

To add one more voice, it doesn't seem possible that the
observed redshift of distant galaxies can be explained in any
other way than as a Doppler shift, with speed proportional
to distance. That means everything is moving apart. Which
in turn means that everything was once close together.
Beyond those near-certainties you start to get scope for
reasonable disagreement. The closer to the initial moment
of creation, the greater the likelyhood of disagreement.

-- Jeff, in Minneapolis

At the risk of appearing picky, but to quell a popular misconception -

The cosmological redshift, due to the large scale expansion of space-time, is not a Doppler Shift, or let's put it this way: one shouldn't use the (special) relativistic Doppler shift formula to compute a cosmological recession speed of a galaxy. See here (http://www.astronomycafe.net/cosm/expan.html), for example.

[ngeo]

At the risk of perpetrating (and perpetuating) a horror story, I will have to stand by my claim, Cougar. The Cambridge Cosmology site you link contains what I have termed “educated speculation” very early in the story: “The Universe began about ten billion years ago in a violent explosion; every particle started rushing apart from every other particle in an early super-dense phase. The fact that galaxies are receding from us in all directions is a consequence of this initial explosion . . . .
“Projecting galaxy trajectories backwards in time means that they converge to a high density state - the initial fireball.”

A beginning? Particles starting to rush apart from each other? An initial explosion or fireball? You can call it something else if you want, but I would call this speculation. And I have an eerie feeling that those interlocking chains of evidence for the “standard” theory (?) hang on the cutting edge research.

However, I can live with “hypothesis” if you like!

[Cougar]

Particles starting to rush apart from each other? An initial explosion or fireball? You can call it something else if you want, but I would call this speculation.This sounds like an argument from incredulity. Whether you are "comfortable" imagining the implications of the theory is really no argument and irrelevant.

At the risk of perpetrating (and perpetuating) a horror story, I will have to stand by my claim, Cougar.
You apparently speak from a dearth of understanding. The third "key observational success" of the standard Hot Big Bang model" listed above, the formation and abundances of the light elements, is really quite a bit more than a "key observational success." As Harvard's GR prof Tony Rothman says....
"When the temperature dropped far below one billion degrees [three minutes after the big bang] this 'primordial nucleosynthesis' stopped and, according to the [quantum] standard model, we should be left with roughly 25% helium by mass and 2 x 10-5 parts deuterium. It may seem like a miracle that astronomers in fact do measure about 25% helium in the real universe, but it is a miracle squared that they also measure something like 2 x 10-5 parts deuterium."
How else could these ratios have come into being? We know quite a bit about how stars fuse hydrogen into heavier elements. There is, in fact, no other way to generate these specific ratios other than the exceedingly hot but quickly cooling environment of a hot big bang.

As one of those linked sites makes clear, the farther back toward the "beginning" we go, the less we know about what's going on. But even I was somewhat surprised in recently reading a book that matter-of-factly stated that today's science has reached the point that we are practically certain about the conditions and processes occurring one second after the "big bang" and thereafter. Apparently these conditions are achievable in the more powerful particle accelerators, and hence can be tested and verified. Earlier than one second is research in progress.

[Ken G]

The Cambridge Cosmology site you link contains what I have termed “educated speculation” very early in the story: “The Universe began about ten billion years ago in a violent explosion; every particle started rushing apart from every other particle in an early super-dense phase. The fact that galaxies are receding from us in all directions is a consequence of this initial explosion . . . .
Yuck, that reads like a list of perpetuated misconceptions. The errors are drastic-- saying the particles "started" rushing apart suggests you had the particles first and then gave them a bunch of energy, when in fact there were two things, energy density and expansion, that appeared right from the start (in the current theory, this part will likely be modified in future). The particles came later. Worse, they call it an "explosion", which is the most widespread of the wrong ideas and it leads to questions like "if light is the fastest thing, why doesn't the light from the explosion expand faster and leave all the matter behind?". It was not an explosion, because an explosion requires a pressure difference between an inside and an outside, and it is the spatially falling pressure that causes the fluid to fly outward toward the lower pressure regions. That is a terribly wrong view of the Big Bang model. So given that they got all that wrong, I wouldn't put too much stock in the "educated speculation" part-- after all, everything in science is educated speculation, all that changes is how much is "educated" and how much is "speculation"!

Particles starting to rush apart from each other? An initial explosion or fireball? You can call it something else if you want, but I would call this speculation. I would too, had that been a reasonable description of the Big Bang theory, rather than the flowery misconceptions it is often reported as.
However, I can live with “hypothesis” if you like!
You won't get far with that term either. This is the word that is used prior to the acquisition of overwhelming scientific evidence.

[Fraser]

If you're interested, we did a two-part Astronomy Cast just on all the evidence for the Big Bang.

Part 1 (http://www.astronomycast.com/cosmology/the-big-bang-and-cosmic-microwave-background/)
Part 2 (http://www.astronomycast.com/extragalactic/more-evidence-for-the-big-bang/)

[ngeo]

From Wikipedia, baryogenesis:
“In physical cosmology, baryogenesis is the generic term for hypothetical physical processes that produced an asymmetry between baryons and anti-baryons in the very early universe, resulting in the substantial amounts of residual matter that comprise the universe today.
“Baryogenesis theories - the most important being electro weak baryogenesis and GUT baryogenesis - employ sub-disciplines of physics such as quantum field theory, and statistical physics, to describe such possible mechanisms. The fundamental difference between baryogenesis theories is the description of the interactions between fundamental particles.
“The next step after baryogenesis, is the much better understood Big Bang nucleosynthesis, during which light atomic nuclei began to form.”

I note that the author here describes hypothetical physical processes but these become the subject of “theories”.

From Wikipedia, Big Bang nucleosynthesis:
“There are two important characteristics of Big Bang nucleosynthesis (BBN):
“-It lasted for only about three minutes (during the period from 100 to about 300 seconds from the beginning of spatial expansion); after that, the temperature and density of the universe fell below that which is required for nuclear fusion. The brevity of BBN is important because it prevented elements heavier than beryllium from forming while at the same time allowing unburned light elements, such as deuterium, to exist.
“-It was widespread, encompassing the entire universe.”

Does the mainstream have overwhelming evidence that only an “initial” - that is, before 100 to 300 seconds after “the beginning of spatial expansion” - hot dense state would create the temperature and density necessary for nuclear fusion? Is there overwhelming evidence that the universe could not possibly create and heat up matter to this temperature and density before “100 to 300 seconds“, during an earlier cooler “phase“?

I would agree that everything in science is educated speculation. Since my provocative comment seems to have precipitated an argument over terminology, I will leave the field to those who appear to have more invested in the precise terminology than I do.

[Ken G]

From Wikipedia, baryogenesis:
“In physical cosmology, baryogenesis is the generic term for hypothetical physical processes that produced an asymmetry between baryons and anti-baryons in the very early universe, resulting in the substantial amounts of residual matter that comprise the universe today.Yes, as I understand it, this is the trickiest part of the current theory. But that is only a problem if you want to understand why the universe has baryons in it-- you can equally well just say there were baryons, and use the BBT to say what happened next. Remember, the BBT is not necessarily all things to all people-- in the final analysis it is just the observational interpretation of a universe expanding from a very hot and dense state.

Does the mainstream have overwhelming evidence that only an “initial” - that is, before 100 to 300 seconds after “the beginning of spatial expansion” - hot dense state would create the temperature and density necessary for nuclear fusion? Absolutely yes.

Is there overwhelming evidence that the universe could not possibly create and heat up matter to this temperature and density before “100 to 300 seconds“, during an earlier cooler “phase“?Yes, that would not agree with the CMB observations, nor the proton/neutron ratio etc., without just inventing new physics with no evidence to support it.



I would agree that everything in science is educated speculation. Since my provocative comment seems to have precipitated an argument over terminology, I will leave the field to those who appear to have more invested in the precise terminology than I do.
It's a hot button topic, because the degree of certainty is always very hard to characterize in science, and this is used to unfairly attack its accomplishments.

[StupendousMan]

Yuck, that reads like a list of perpetuated misconceptions. The errors are drastic-- saying the particles "started" rushing apart suggests you had the particles first and then gave them a bunch of energy, when in fact there were two things, energy density and expansion, that appeared right from the start (in the current theory, this part will likely be modified in future). The particles came later. Worse, they call it an "explosion", which is the most widespread of the wrong ideas and it leads to questions like "if light is the fastest thing, why doesn't the light from the explosion expand faster and leave all the matter behind?". It was not an explosion, because an explosion requires a pressure difference between an inside and an outside, and it is the spatially falling pressure that causes the fluid to fly outward toward the lower pressure regions. That is a terribly wrong view of the Big Bang model. \

I am firmly convinced that the hot Big Bang model is the best explanation we have so far. I also agree that it is easy to criticize some descriptions of the model, as Ken G. does above. However, I must admit that it is not very easy to provide a quick answer to the question "What is the Big Bang theory?" without using some of the words we often criticize.

Let me try:

Me: "The universe was once very hot and very dense. It very quickly became less hot and less dense ..."

Listener: "You mean it exploded?"

Me: "Well, no. It was expanding, but not exploding. All parts of space were moving away from all other parts of space, see, and ..."

Listener: "So particles were moving away from each other, like galaxies are today?"

Me: "Yes, exactly -- well, no. There weren't any atoms, and familiar particles like electrons and protons represented only a tiny portion of the mass-energy density at time, which was dominated by ..."

Listener: "ZZzzzzzzzzz....."

If one very carefully picks ones words, one has a difficult time keeping the discussion brief and easily understood. The conditions at that time were not at all like those today. It is difficult, perhaps impossible, to draw analogies which the layman will understand without resorting to some level of inaccuracy.

Perhaps I'm wrong. If someone can provide a good description of the Big Bang theory in 30 words or fewer, prove me wrong. Then we can all use that description in the future :-)

[Cougar]

Yuck, that reads like a list of perpetuated misconceptions.
Well, I have to agree. That introductory paragraph appears designed for a very lay audience. Considering that all the linked sites are supposed to be "What the Standard Hot Big Bang Theory Really Says," this is not good. I believe the ensuing discussion and the other links are more in keeping with the intended purpose.

...everything in science is educated speculation, all that changes is how much is "educated" and how much is "speculation"!
Ken, speculation is commonly interpreted to mean "A judgment, estimate, or opinion arrived at by guessing: conjecture, guess, guesswork, supposition..."

This is clearly not what "everything in science is."

...I will leave the field to those who appear to have more invested in the precise terminology than I do.
As demonstrated by the above definition of speculation, "precise terminology" can make the difference between whether your statement is wrong or right. Surely you have some "investment" in such things?

[Cougar]

Does the mainstream have overwhelming evidence that only an “initial”... hot dense state would create the temperature and density necessary for nuclear fusion?
Ken answered (correctly) what you meant to ask, but your question is rather ambiguous. Of course "nuclear fusion" occurs in stars. The point is that only an initial hot, dense (and rapidly cooling) state would create the observed relative amounts of hydrogen, helium, dueterium, and lithium nuclei from fusing the hydrogen nuclei.

It's a hot button topic, because the degree of certainty is always very hard to characterize in science, and this is used to unfairly attack its accomplishments.
Entire books have been written about certainty in science. Here's a good one: Searching For Certainty, What Scientists Can Know About the Future [1990] -- John L. Casti

Another good one along the same lines: The Universe, the Eleventh Dimension, and Everything: What We Know and How We Know It -- Richard Morris

[Cougar]

Perhaps I'm wrong. If someone can provide a good description of the Big Bang theory in 30 words or fewer, prove me wrong. Then we can all use that description in the future :-)
No way. Earlier today I tried to summarize the "Big Bang Scenario" (http://www.bautforum.com/showpost.php?p=904169&postcount=128) in 100 words or less. I quickly went over and still had to leave out A LOT.

[Tim Thompson]

How Sure Are We?
What was the last thing that Tonto (http://en.wikipedia.org/wiki/Tonto) said to The Lone Ranger (http://en.wikipedia.org/wiki/The_Lone_Ranger)? What do you mean we, white man! :)

If by "we" you mean professional astronomers, astrophysicists, cosmologists & etc., then the answer is that "we" are 100% sure that big bang cosmology is the best model we have to work with. We (I include myself now) are every bit as convinced of the validity of big bang cosmology as are biologists convinced of the validity of evolution. But of course, both evolution & big bang cosmology (BBC) have their critics, and in both cases some of those critics are found in the appropriate professional ranks, and so are not necessarily simply uninformed outsiders.

A trip through the ATM forum might lead one to think that BBC is more "controversial" than it really is, just as various types of creationists try to generate "controversy" over evolution, where none really exists. The reality is that, in both cases, the vast majority of the critics don't know enough to generate valid criticisms, and the vast majority of mainstream scientists have neither the time nor patience to deal with them. So, much criticism goes unanswered, creating the illusion that scientists have no response to a legitimate criticism, when the reality is that they just don't care enough to bother. Personally, I am somewhat amused by the force of emotion & character that goes into debating something like cosmology, which is about as far removed from the realm of the scientifically useful as one can get. It's a cinch that whatever the "true" cosmology is, if you don't like it, there isn't much you can do about it.

There is another point worth making. Science is a very operationally oriented affair; it's all about how, not why. It is not possible to ever determine if any scientific theory is true, but it is possible to determine whether or not a scientific theory works. By "works", we mean to say, whether or not a scientific theory is consistent with observed facts, and also consistent with other applicable, accepted, scientific theories. The vast majority of "us" are firmly convinced that this is the case for BBC. But theories can & do change, and if a better one comes along, it will take over fairly quickly. I don't see that happening any time soon. Personally, I don't think it will ever happen; it would be equivalent to coming up with a better idea than Newtonian physics for classical mechanics, and that isn't going to happen either.

And finally, one more important point. BBC is not a theory, it is a family of theories, really a metaphysical principle more than a physical one. It is the primary constraint that the universe is dynamic & expanding. There are zillions of ways to do that, and a lot of them are consistent with observation. So, we need to weed out the ones that don't work. As our ability to observe expands & deepens, so does our ability to distinguish between theories that do & don't work. Critics see this as a sign of weakness, while mainstream scientists see it as a sign of strength. This serves to emphasize just one of many major, philosophical differences between the mainstream and its critics.

[back-marker]

Yes, that's what I meant by we. The experts in the field.

I have been debating theists on You Tube and want to make sure I am not overstating how sure we are of it. Not that it will matter since the vast majority don't even have a concept of what a scientific theory is, but I keep plugging away at them.

[ExpErdMann]

What was the last thing that Tonto (http://en.wikipedia.org/wiki/Tonto) said to The Lone Ranger (http://en.wikipedia.org/wiki/The_Lone_Ranger)? What do you mean we, white man! :)

If by "we" you mean professional astronomers, astrophysicists, cosmologists & etc., then the answer is that "we" are 100% sure that big bang cosmology is the best model we have to work with.

Now is that 100% or 99.99...% ? In another thread you cited the QSSC as the best alternative model to the Big Bang. Seems to me that someone who is 100% sure of his model would have to assign 0.00% to the alternatives, eliminating them from all discussion. Just curious.

Also, I seem to recall a recent poll of astronomers and physicists that gave a much less hearty endorsement of the Big Bang model, something like 75%. Does anyone remember where that poll was?

[Tensor]

Now is that 100% or 99.99...% ? In another thread you cited the QSSC as the best alternative model to the Big Bang. Seems to me that someone who is 100% sure of his model would have to assign 0.00% to the alternatives, eliminating them from all discussion. Just curious.

The QSSC can be the best alternative model and still not be a worthwhile alternative. Seems to me that all Tim meant was that the QSSC can explain more observations than any of the other alternatives. That doesn't mean that is can explain enough of them to be a worthwhile competitor to the BBC.

[Cougar]

Also, I seem to recall a recent poll of astronomers and physicists that gave a much less hearty endorsement of the Big Bang model, something like 75%. Does anyone remember where that poll was?
This must have been in that dream you had the other night. :whistle:

[Ken G]

Ken, speculation is commonly interpreted to mean "A judgment, estimate, or opinion arrived at by guessing: conjecture, guess, guesswork, supposition..."Then you are saying that "educated speculation" is an oxymoron, so that's hardly much better. I was giving them the benefit of the doubt that it's possible to "educate" speculation.

[snarkophilus]

Also, I seem to recall a recent poll of astronomers and physicists that gave a much less hearty endorsement of the Big Bang model, something like 75%. Does anyone remember where that poll was?

Were 25% of them YECs?

How else could these ratios have come into being? We know quite a bit about how stars fuse hydrogen into heavier elements. There is, in fact, no other way to generate these specific ratios other than the exceedingly hot but quickly cooling environment of a hot big bang.

That's a dangerous sort of thing to say. There certainly could be other ways. Just none conceived are so simple or useful.

Here's my shot at Big Bang cosmology in 100 words or less. (We should have a contest for this!)

In the beginning, there was space. Right around the beginning, it was all packed into a tiny little volume (maybe even 0 volume). The space expanded, and then there was light. And a quark soup. Space expanded more, causing the temperature to drop. The quarks congealed into the matter we see today, giving off what we now see as the CMB. Space kept expanding, and it was cool enough for atoms to form. Also, somewhere along the line, gravity became important (relative to radiation), and that caused the matter to clump in a way that eventually produced galaxies and stuff.

Mmm... quark soup....

[Ken G]

Not that it will matter since the vast majority don't even have a concept of what a scientific theory is, but I keep plugging away at them.

I firmly believe this is the real issue, not who is "right". Right and wrong are philosophical concepts, I agree with Tim Thompson that what science is about is what works. This is a hugely liberating principle for science, and this, along with its flexibility in the face of change, are among its great strengths. So the real issue of importance in communication with nonscientists is not why science is right (you'll argue that until you are blue in the face and you still can't prove anything), it's what is science, how do its principles get applied, and how many concrete tests has it passed. Science is a process, not a destination, and at any point along the way, it is measured by the value it has generated at that point. Those are the "true" things that distinguish science, not being "right". Indeed, the history of science is a trail of carnage from the point of view of being right!

[Ken G]

Here's my shot at Big Bang cosmology in 100 words or less. (We should have a contest for this!)

In the beginning, there was space. Right around the beginning, it was all packed into a tiny little volume (maybe even 0 volume). The space expanded, and then there was light. And a quark soup. Space expanded more, causing the temperature to drop. The quarks congealed into the matter we see today, giving off what we now see as the CMB. Space kept expanding, and it was cool enough for atoms to form. Also, somewhere along the line, gravity became important (relative to radiation), and that caused the matter to clump in a way that eventually produced galaxies and stuff....

I'll have a go:
The large-scale force in the universe is gravity. This leads to instability, and means the universe has to be dynamical-- i.e., in motion. Thus it either has to be expanding or contracting, and it can be doing it differently everywhere or the same everywhere. Observations show it is expanding everywhere, and there is no evidence that this varies with location on the largest scale, but it does with age (being dynamical). No known physics could have started the expansion other than the beginning of our universe, and as it expanded, it cooled dramatically, generating the matter we now find.

[ngeo]

In response to my question, “Is there overwhelming evidence that the universe could not possibly create and heat up matter to this temperature and density before “100 to 300 seconds“, during an earlier cooler “phase“?” Ken G wrote, “Yes, that would not agree with the CMB observations, nor the proton/neutron ratio etc., without just inventing new physics with no evidence to support it.”

Taking out any particular number of seconds, exactly what is the overwhelming evidence of disagreement with CMB observations and proton/neutron ratio etc. for a universe that did create and heat up matter to the temperature and density necessary for nuclear fusion prior to nucleosynthesis, as opposed to one that was cooling down already existing matter? (This is to neither agree nor disagree with the related subject of stellar nucleosynthesis having produced all the elements.)

As far as the microwave background is concerned, there is a feature of the FIRAS instrument that I would like explained, which is that there were two blackbodies on this instrument: an external calibrator which was removed periodically, and an internal calibrator through which half the photons passed in making the spectrogram. It seems to me this internal blackbody calibrator guarantees a blackbody. Can anyone say why this should not be so?

[Ken G]

Taking out any particular number of seconds, exactly what is the overwhelming evidence of disagreement with CMB observations and proton/neutron ratio etc. for a universe that did create and heat up matter to the temperature and density necessary for nuclear fusion prior to nucleosynthesis, as opposed to one that was cooling down already existing matter? It's simply lack of known physics. If I'm unconstrained by known physics, I'm not doing science at all, I'm just telling a made up story that can be fit to observations. First this happened, for no reason, then that happened, also for no known reason. But the goal of science is to take processes you already understand and try to use them to explain something you don't understand yet. If you succeed, and can make predictions of new observations, then you have a working theory, not just a story. You can pretty much start the Big Bang any time you want, because physics doesn't explain starting points it explains evolution of starting points, but after that you have to just follow the physics as you know it and see what you get. Extrapolating time backward from a certain point can also be a useful way to anticipate and predict the results of new observations, but of course once you have gone back as far as you can possibly get any new constraints or data, even in principle, you have gone back as far as science can take you. Some might argue you can take the physics back even before there is any possibility for direct or indirect observational confirmation, but that's just a subjective opinion of theirs-- my statement is the only one supportable by actual science.

[Tim Thompson]

As far as the microwave background is concerned, there is a feature of the FIRAS instrument that I would like explained, which is that there were two blackbodies on this instrument: an external calibrator which was removed periodically, and an internal calibrator through which half the photons passed in making the spectrogram. It seems to me this internal blackbody calibrator guarantees a blackbody. Can anyone say why this should not be so?
I can say why it should not be so. The easiest way to tell if you are observing a blackbody is to measure the difference between the observed signal and a known reference signal. The internal calibrator can be adjusted to a known temperature. If the difference between the signal from the internal calibrator & the sky is zero, then you know that the sky is a blackbody at the temperature of the calibrator (which is why it has to be adjustable). It's always easier to measure departures from zero than "absolute" signals (there are no truly absolute measurements anyway). The external calibrator fills the field of view with a known blackbody. So you compare that to the internal calibrator, and if you don't see a zero spectrum, then you know there is a systematic error inside the instrument, contaminating the results, which you can subsequently account for. So, when the COBE team reports a final result of 2.725±0.002 K (Mather, et al., 1999 (http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v512n2/38652/38652.html?erFrom=-6408360003734775772Guest)), the 0.002 comes primarily from the uncertainty in the deviation from zero in the difference between the sky & the reference. The calibration of FIRAS is described in Fixsen, et al., 1994 (http://adsabs.harvard.edu/cgi-bin/bib_query?1994ApJ...420..457F). Also see the FIRAS instrument webpage (http://lambda.gsfc.nasa.gov/product/cobe/about_firas.cfm).

[Cougar]

How else could these ratios have come into being? We know quite a bit about how stars fuse hydrogen into heavier elements. There is, in fact, no other way to generate these specific ratios other than the exceedingly hot but quickly cooling environment of a hot big bang.
That's a dangerous sort of thing to say. There certainly could be other ways. Just none conceived are so simple or useful.
Yes, I've gone a bit out on a limb here, but the limb is pretty solid. I believe it's a fact that no other way has been conceived. Ask Hoyle. (Well, he's dead now, but you can read his stuff.) He was trying to show how stars could generate the observed ratios of elements in order the support his steady state theory. Instead, he essentially showed how they couldn't, thus providing one of the strong pillars of the big bang (and laying the groundwork for the theory of stellar evolution in the process, IIRC.)

But it's remotely possible that there could be other ways that no one has yet imagined to generate the observed elemental abundances. But the limb is solid because it is based on our understanding of quantum physics, which is considerable.

Here's my shot at Big Bang cosmology in 100 words or less. (We should have a contest for this!)

In the beginning, there was space. [Big bang doesn't say this!] Right around the beginning, it was all packed into a tiny little volume (maybe even 0 volume). The space expanded, and then there was light. And a quark soup. Space expanded more, causing the temperature to drop. The quarks congealed into the matter we see today, giving off what we now see as the CMB. [Not even close!] Space kept expanding, and it was cool enough for atoms to form. Also, somewhere along the line, gravity became important (relative to radiation), and that caused the matter to clump in a way that eventually produced galaxies and stuff.

Sorry to be so critical, but this is not a very good summary of what big bang cosmology says. :o Go back to those links I gave earlier. They generally give a very good explanation of what the big bang is... and isn't.

[back-marker]

The only book I've read devoted to The Big Bank Theory was The First Three Minutes by Steven Weinberg. It was probably over a decade ago when I read it. I'm sure there have been many more pieces to the puzzle that have been added since he first published it.
I'm wondering what book you guys would recommend today.
Thanks

[ngeo]

Thank you Tim Thompson, I have read the papers you link and you add clarity.

“The internal calibrator can be adjusted to a known temperature. If the difference between the signal from the internal calibrator & the sky is zero, then you know that the sky is a blackbody at the temperature of the calibrator (which is why it has to be adjustable).”

My problem is that if the signal from the sky becomes mixed with a blackbody signal from the internal calibrator, it cannot be known whether the signal from the sky is a blackbody since the blackbody projects a blackbody pattern onto the final signal.

[Ken G]

My problem is that if the signal from the sky becomes mixed with a blackbody signal from the internal calibrator, it cannot be known whether the signal from the sky is a blackbody since the blackbody projects a blackbody pattern onto the final signal.

You are unaware of the "principle of superposition" as applies to light, which means that if you superimpose one signal on another, with no coherence relation between them, then the detector will measure the simple sum of the two. It's just like when you add two apples to two apples, you get four apples, but nothing happened to either of the original groups of two. There is no "projecting" of patterns onto each other, just a sum, and this is the simple algebra used in the experiment.

[ngeo]

Thank you Ken G. I will respond to your earlier comments above in the "questions on space etc." thread. Re your comment immediately above, what happens if there is no sky signal?

[Tensor]

Thank you Ken G. I will respond to your earlier comments above in the "questions on space etc." thread. Re your comment immediately above, what happens if there is no sky signal?

Then you would only get the internal signal, but that is a known factor and can be subtracted out. Why would they do that? That is the secret of Heterodyning (http://en.wikipedia.org/wiki/Heterodyne). In the case above, you would combine the known internal signal with the sky signal. With no sky signal all you have is the internal signal and when that is subtracted out, you end up with no signal at all. Just what is coming from the sky in your example.

[ngeo]

Thank you Tensor, I am convinced there is a microwave background signal.

[Cougar]

The only book I've read devoted to The Big Bank Theory was The First Three Minutes by Steven Weinberg. It was probably over a decade ago when I read it. I'm sure there have been many more pieces to the puzzle that have been added since he first published it.
I'm wondering what book you guys would recommend today.
That is a classic. But it was written in 1977, so yes, it doesn't get into Guth's theory of inflation or the newer finding of acceleration of the expansion. Here is an excellent, more up to date overview....

Blind Watchers of the Sky, The People and Ideas that Shaped Our View of the Universe [1996] -- Rocky Kolb

Then to get the word on inflation from the horse's mouth....

The Inflationary Universe, the quest for a new theory of cosmic origins [1997] -- Alan H. Guth

One of the first to address the supernova Ia findings of acceleration....

The Runaway Universe, the Race to Find the Future of the Cosmos [2000] -- Donald Goldsmith

These are just good, recent books....

The Universe at Midnight, Observations Illuminating the Cosmos [2001] -- Ken Croswell

Alpha and Omega, The search for the beginning and end of the universe [2004] -- Charles Seife

[Nereid]

[snip]

A trip through the ATM forum might lead one to think that BBC is more "controversial" than it really is, just as various types of creationists try to generate "controversy" over evolution, where none really exists. The reality is that, in both cases, the vast majority of the critics don't know enough to generate valid criticisms, and the vast majority of mainstream scientists have neither the time nor patience to deal with them. So, much criticism goes unanswered, creating the illusion that scientists have no response to a legitimate criticism, when the reality is that they just don't care enough to bother.Somewhat OT, but it would also seem that many of those ATM critics have huge issues with all of astrophysics (except, perhaps, when applied to solar system objects), not just the BBT. Personally, I am somewhat amused by the force of emotion & character that goes into debating something like cosmology, which is about as far removed from the realm of the scientifically useful as one can get. It's a cinch that whatever the "true" cosmology is, if you don't like it, there isn't much you can do about it.

[snip]One of the ironies here is the huge amount of emotion devoted to cosmology vs the apparent complete acceptance of just about every other application of physics to astronomy* (outside the solar system), with no awareness, let alone acknowledgement, of the double standard! :surprised

*Except for dark matter.

[antoniseb]

Here's my own version of 'Big Bang Cosmology'
Take a sphere of finite size. Spin it.

This handwaving is fine. If you'd like to discuss this in more detail, please open a thread in the Against The Mainstream section below.

[Mad_Morlock]

No hand waving, actually.

But I did draw a picture.

[link to ATM thread removed]

[Nereid]

Mad_Morlock, please read the PM I sent you, re posting of ATM ideas outside the ATM section of BAUT.

[Mad_Morlock]

It's actually not against the mainstream.

The swartzchild metric is very much a part of the mainstream.

The white hole metric is just tossed aside as imaginary gibberish produced by the mathematics. Much like Dirac's Sea of Negative Energy.

[Ken G]

The reason your ideas are ATM have nothing at all to do with using white hole solutions to GR, it is an even easier reason: they do not agree with observations. They only "agree" with your ATM (and incorrect to any educated astronomer) interpretations of observations. If I look up at constellations and see the Mona Lisa, do I now have a mainstream argument that Leonardo DaVinci created the universe? Constellations are mainstream, right?

[Mad_Morlock]

You know for a while educated people believed that the world was flat.

And that the sky was a big bowl placed over the Earth.

How do you know what to look for when looking for a White Hole? What do you think one would look like? How would you tell the difference between a black hole and a white hole?

[Ken G]

How would you tell the difference between a black hole and a white hole?

Those, my friend, are the questions for you to answer-- you are proposing the theory!

[Mad_Morlock]

Those, my friend, are the questions for you to answer-- you are proposing the theory!

Ok... here's some postulates.

1. A white hole would appear to be massive, like a Galactic Central Core black hole.

2. It would mostly like have an accompanying relativistic jet.

3. It would not have a well defined galactic formation. Instead it would appear to be surrounded by a gaseous cloud.

[Ken G]

Ok... here's some postulates.

1. A white hole would appear to be massive, like a Galactic Central Core black hole.

2. It would mostly like have an accompanying relativistic jet.

3. It would not have a well defined galactic formation. Instead it would appear to be surrounded by a gaseous cloud.

Your 1 and 2 sound like you have white holes all over the place, I'm missing how this is evidence for one superhuge one.

[Cougar]

Ok... here's some postulates.
Mr. Mad, if you want to discuss something different than the subject of an existing thread, you should start your own thread. I'm sure people will be glad to participate in your thread and tear your ideas apart... or otherwise comment on your ideas in one form or another. ;)

As Moderator Antoniseb just said:

"If you'd like to discuss this in more detail, please open a thread in the Against The Mainstream section below."

[Mad_Morlock]

Ok... I'll close this one off. (Postulate 3 should have cleared that up for you. Examine M87)

(Rest moved to Hawking Radiation.)

[Cougar]

I'll close this one off.... Back to Hawking Radiation?
Ha. With all the threads and forums happening here in parallel, I understand how easy it is to forget what thread you're in! This is The Big Bang Theory - How Sure Are We? I think the correct answser is, pretty darn sure. Of course, as clarified in this thread, the "big bang theory" is really a large collection of interlocking theories, all fitting together. And that's one of its strengths -- it all fits quite well.

[Mad_Morlock]

Yeah... we can describe big bang nucleosynthesis to a T... we can explain how it relates to CMB.

But what sets up the inital conditions for the BB?

I think the White Hole metric contains the solution, which is why I originally brought it up.

(I'll transfer that to the Hawking Thread.)