Is Big Bang True? Physics and SR/GR

[Drakkith]

If you have learned about Compton scattering, you'll understand the energy of quanta decreases, this happens because photon collides with electron and change its direction and give electron some energy, thus, photon loses some of its energy

Which doesn't explain redshift, as the absorption and emission spectra of different objects is equally redshifted, which wouldn't be the result of compton scattering. Do you know what absorption and emission spectra are?

 

[SHISHKABOB]

If you have learned about Compton scattering, you'll understand the energy of quanta decreases, this happens because photon collides with electron and change its direction and give electron some energy, thus, photon loses some of its energy

so there are clouds of electrons floating in space between us and galaxies, etc. and these clouds are such that they exactly change the energy (and thus frequency) of intervening photons that they appear to be red-shifted?

That's what it sounds like you're implying. Otherwise how does Compton scattering play into the red-shifting of light from so many sources?

The red-shifting of light even correlates with distances determined through other methods, I think. Is this correct? For example Andromeda. I'm pretty sure we can look at the blue-shift of the light coming from Andromeda, but we can also use the Cepheid variable stars their. I have never heard of any disagreement there.

 

[Chalnoth]

If you have learned about Compton scattering, you'll understand the energy of quanta decreases, this happens because photon collides with electron and change its direction and give electron some energy, thus, photon loses some of its energy

Bear in mind, however, that inverse Compton scattering also occurs, where the electron adds energy to the photon.

That said, since the CMB was emitted, our universe has been extraordinarily transparent. WMAP estimates that approximately 92% of the light from the CMB arrives at us without scattering.

 

[clamtrox]

Matter can be and is created and destroyed all the time. We do it in particle colliders every day here on Earth. ENERGY and MASS cannot be destroyed or created, only transferred. Furthermore, the theory of the Big Bang never says that this energy was created from nothing. It only describes the universe after a certain point in time after the Big Bang. What happened before this point in time is beyond that model.

Energy is a coordinate-dependent quantity, and even worse, it's not really conserved in GR anyway (remember that the conservation law is about the energy-momentum tensor, not a single component of it). Mass is only due to interactions with the Higgs field so you shouldn't really be so zealous about them either.. :-)

Usually how one thinks about this is that the gravitational field's energy (which is a muddy concept so I'm not going to be very precise about it) is negative, and for a flat universe, you can show that the sum of gravitational energy and energy of the matter content is exactly zero. So there is nothing (or atleast energy conservation) stopping you from having a theory of quantum gravity which produces flat universes out of the vacuum.

 

[CaptFirePanda]

If Big Bang is true, and it's not Compton scattering that cause the redshift. Then explain this
http://www.thunderbolts.info/tpod/2011/arch11/110329redshifts.htm
This throw doubt on the Big Bang

Where is the proof the NGC 7319 is opaque? Also, I'm pretty sure your reference has no associated credibility.

 

[Eric333]

philosophically big bang is the most likely, as everything would have to start somewhere...how it happened is of course the question being investigated.

 

[Mark M]

philosophically big bang is the most likely, as everything would have to start somewhere...how it happened is of course the question being investigated.

'Philosophically' does not matter. What matters is scientific evidence, and that's why we KNOW the big bang model is correct.

 

[clamtrox]

philosophically big bang is the most likely, as everything would have to start somewhere...

Can you show your work? How do you evaluate the probability?

 

[DaveC426913]

Can you show your work?

 

[Chiclayo guy]

If the Big Bang was thought of as an event of no real consequence – not really the beginning of anything - merely a hiccup or burp in an eternal and infinite universe, would that in any way influence the thinking, assumptions or focus of present investigation?

 

[Drakkith]

If the Big Bang was thought of as an event of no real consequence – not really the beginning of anything - merely a hiccup or burp in an eternal and infinite universe, would that in any way influence the thinking, assumptions or focus of present investigation?

We would only think this if we found evidence for it, which would most definitely influence many things.

 

[Mark M]

If the Big Bang was thought of as an event of no real consequence – not really the beginning of anything - merely a hiccup or burp in an eternal and infinite universe, would that in any way influence the thinking, assumptions or focus of present investigation?

It wouldn't affect the big bang model, no. The big bang model merely attempts to describe the universe after the big bang, how the particles and elements formed, and how structures developed.

As Drakkith points out, it most certainly would have an affect on our thinking in other areas. But if we discovered the big bang was the beginning, I think that would have an effect too - we don't know which is true, even though the idea of the big bang being the beginning of time became more popular because of the Hawking-Penrose singularity theorems. What happened at or before the big bang doesn't have any relevance to the big bang model itself.

 

[Flowerpunkt]

Q: So, is Big Bang true or wrong?

A: Its definitely not true ... since any scientific theory can't be proven (can be only confirmed to a certain level).
This is a wrong question to me and it should not bother science.

 

[DaveC426913]

Q: So, is Big Bang true or wrong?

A: Its definitely not true ... since any scientific theory can't be proven (can be only confirmed to a certain level).
This is a wrong question to me and it should not bother science.

We have a preponderance of evidence that the universe started off very small and very dense. You are correct that it cannot be "proven". Science does not attempt to prove things. However, science is perfectly happy with moving forward based on our best models, and we have a pretty good one regarding the Big Bang.

 

[Chalnoth]

Q: So, is Big Bang true or wrong?

A: Its definitely not true ... since any scientific theory can't be proven (can be only confirmed to a certain level).
This is a wrong question to me and it should not bother science.

It is true in the sense that it's an accurate description of reality...up to a point.

 

[audioloop]

there are various proposals,
Hartle-Hawking's no-boundary wave function, Linde's wave function, Vilenkin's tunneling wave
function...
they predict different types of gravity waves.

 

[Chiclayo guy]

We have a preponderance of evidence that the universe started off very small and very dense. You are correct that it cannot be "proven". Science does not attempt to prove things. However, science is perfectly happy with moving forward based on our best models, and we have a pretty good one regarding the Big Bang.

As an unofficial representative of the average public mind let me suggest that this is one of the issues within cosmology that absolutely confounds Mr John Q Public. If I may paraphrase hundreds if not thousands of comments…”The universe started everywhere, not at one central point.” Everywhere to me implies vastness…lots of distance plus locations like ‘here’ and ‘there.’

To say that the universe “started off very small” (I have seen estimates of golf ball and grapefruit size) seems to me to be diametrically opposed to ‘everywhere.’ I’ve tried to reconcile the problem by merging the two views… the universe started everywhere within the golf ball, but that sounds more like tap dancing than a plausible explanation.

I’m sure I’m not understanding something, but I’m just as certain that my fellow average public minds are as confused as I am. Is there no way to put layman speak to the issue so we can put it aside and go on to other concepts that we have absolutely no understanding of?

 

[Chalnoth]

I’m sure I’m not understanding something, but I’m just as certain that my fellow average public minds are as confused as I am. Is there no way to put layman speak to the issue so we can put it aside and go on to other concepts that we have absolutely no understanding of?

The way I usually prefer to put it is that in the distant past, things in our universe were much closer together. Go early enough, and everything that we can see was once contained in a volume smaller than an atom. Now, we're pretty sure that the universe continues some distance beyond what we can see, so we don't know just how big the universe was (if it even has a size!), but everything we can see came from just one teeny tiny patch.

 

[phinds]

I have seen estimates of golf ball and grapefruit size

I think you'll find that those are estimates of the OBSERVABLE UNIVERSE at the beginning, NOT "the universe"

 

[Drakkith]

I’m sure I’m not understanding something, but I’m just as certain that my fellow average public minds are as confused as I am. Is there no way to put layman speak to the issue so we can put it aside and go on to other concepts that we have absolutely no understanding of?

Imagine if everything in the observable universe (that means the parts we can see) occupied a volume of space no bigger than a golf ball. Now imagine a possibly infinite number of golf balls surrounding ours in every direction. That is what we think the early universe was like. Hot, dense, and still possibly infinite in size.

 

[Mark M]

One point to add to the previous few posts - even if the universe is finite (e.g. it has a positively curved topology, or that of a 3-torus), it remains true that it has no boundary. To get an analogy in lower dimensions, think of the surface of the earth. It has no edge, no boundary, but we can still speak of it's overall size (the distance required to circumnavigate it's surface). Generalize this to three dimensions. No matter how far you travel, you'll never encounter an edge. You'll just wrap back around, like a three dimensional analogue of Pac-man.

So, we can say two things - the universe has no boundary, and it has no outside.

 

[cueball B]

I have heard OP's arguments before. It was in a creationist VS science debate, to discredit the big bang theory and science, without bringing forward any proof to show why their model of the universe would be more plausible.

 

[phinds]

I have heard OP's arguments before. It was in a creationist VS science debate, to discredit the big bang theory and science, without bringing forward any proof to show why their model of the universe would be more plausible.

Yes, the OP was presenting a thoroughly non-scientific point of view and you will notice that once people pushed back on his nonsense he was not heard from again.

 

[profgemelli]

I have heard OP's arguments before. It was in a creationist VS science debate, to discredit the big bang theory and science, without bringing forward any proof to show why their model of the universe would be more plausible.

Boys listen to this and have a laugh. I have wondered for weeks what this "OP argument" was. I am interested in cosmology and alternative cosmologies, and I believed it had to be some well-known philosophical argument, and searched it on the internet. I found hundreds of citations of the socalled "OP argument", in many different fields, and I was puzzled about what it was, or what O and P stand for or who was this OP... I was about to write here to ask, when I eventually came across a site about internet slang, where I finally understood that OP stands for "Original Poster", and so it is not a specific argument! :-D

 

[Chronos]

Well, if you push the universe back to t=0, it was not even the size of a golf ball, or even an atom - it was a point of zero size and infinite density. Most cosmologists would agree this is unrealistic and signals the laws of physics, as we know them, are incomplete. It's not much different than the case of a point charge which, in theory, should have an infinite charge density. We are still working on the cosmological case by trying to formulate a theory of quantum gravity.