Did the Big Bang happen?

[Peebothuhlu]

I’m gonna try to reply to everyone who asked me stuff while I was out lol. I’m tired so I apologize if I miss anything.

1. On the whole whether finite or infinite, the universe does not “require God” to explain the science: I agree. I see God less and less as the ‘thing’ that fills in the gaps these days and take a much more purely fideistic approach to faith. So my asking these questions is, legitimately, not faith-driven. I am curious about the science.

2. Do I think the universe is finite or infinite? Um… I have no idea. I like the idea of the universe possibly being curved and therefore being a four-dimensional sphere. But even with such a model where if you keep going in one direction theoretically you could end up back in the same place, that doesn’t mean the universe is finite from a time perspective.

3. I like the theory of quantum eliminating the singularity causing an infinite state of time before the Big Bang. It is much simpler to my mind than trying to figure out what “happened” “before time”.

4. When I said always I was speculating a universe that has existed forever. Infinite time.

Hello!

Welcome to the forums and stuff.

I've been following along and learing stuff from other posters.

Here's something I've heard/read back a while.

So, you may of may not be familiar with the 'Rest State' of electrons? (I'm also not sure of positrons and neutrons have 'Rest stastes, either).

The comentor made the point that this 'Rest stat seem to 'Just be'. You know, one of those things the diety beatifyers latch onto and keep calling "Fine Tuning".

Well said comentor then suggested... what if it ISN'T fixed? What happens if somthing causes that energy level to change? As in an electron loses even more of its energy 'some how'?

The conjecture is that said atom would hence change its rather fundamental properties... potentially leading to a cascade effect reaching even deeper into the 'String level' or reality.

VORP!

Suddenly you have a 'New' state of elemental 'Being' resetting everything outwards from itself at the speed of light.

Indeed, the talker mentioned that because said change front is moving at the speed of light we never see it comming if, indeed, such a thing were even occuring.

I think they then moved on to explaining why some Cosmologists suggest that as the heat death of everything draws on, that the potential for such a 'Resettting tear' becomes more imaginable.

Whole ;New' realities being born in such 'Tears' in our fading, stretching, freezing, dark exhausted heat death future.

Hope I haven't butchered the memory too badly. Perhaps some one more learned on the forums can give the whole thing a better explanation?

All the best.

Cheers.

Not at work.

[Jehanne]

In his undergraduate textbook, Modern Physics (4th edition), Professor Kenneth S. Krane discusses cosmology in his last chapter.  In it, he states that the Universe is either finite or infinite in spatial extent.  Do you agree?  He also states that General Relativity can handle both scenarios, a finite Universe or an infinite one.  In either scenario, our Universe is expanding.  Of course, if our Universe is infinite, then, it is certainly conceivable that there are events that occurred in our infinite past or will occur in our infinite future, given that the speed of light, the rate of information transfer, is finite.

Now, if our Universe is finite, it is expanding, not only into its future, but in all three spatial directions, hence, its overall volume is increasing over time.  What, exactly, do you think, in this scenario, the Universe is expanding "into"?

When cosmologists speak of the universe being finite or infinite, they usually mean in spatial extent using a comoving frame.

In the classical version of general relativity, there were three options: either space is positively curved (like a sphere) and time is finite in both directions, space is flat (like a plane) and time is infinite into the future but not the past, or space is negatively curved (like a saddle) and time is infinite into the future and not into the past.

Which of the three possibilities actually occurs depends on the density of matter and energy: a higher density leads to more gravity and an eventual collapse associated with the positive curvature. Less density leads to negative curvature and expansion forever. A critical density leads to flatness (and, yes, expansion forever).

This whole description became more complicated with the discovery of dark energy (also known as the cosmological constant). Einstein had originally introduced this notion as a way of having a static universe but it was discarded (except for graduate student exercises) after the expansion of the universe was discovered.

I won't go into specifics, but the nice trichotomy above is shifted and it is possible to have expansion forever even if the universe is positively curved.

Anyway, in anything based on general relativity and NO quantum mechanics, the universe is finite into the past.

The question of what the universe is expanding into is a subtle one and requires a bit different perspective.

In modern cosmology, we discuss the geometry of spacetime, not just of space itself or time itself. The two together form the basic geometry of the universe. So when a cosmologists models the universe, they model it throughout both space and time as a single object. All dynamics occur within this object at different time slices.

So, as an analogy, I'm going to describe a 'universe' that is one dimensional in space and one dimensional in time and that is also curved in spacetime.

Imagine a globe. Imagine the latitude of a point describes the time and the longitude describes the spatial location. The two together will characterize the point. We imagine points further south are previous to those further north.

Space is then the collection of points at a particular time: this corresponds to a latitude line.

Now, starting at the 'beginning' of the south pole (more about this later), the latitude lines get larger as we approach the equator: in other words, space is expanding as we move forward in time. At the equator, we have maximum expansion, and then space begins to contract until we get to the end (the north pole).

So, looking at this analogy: what does space expand into?

The answer, literally and geometrically, is *the future*. And that is the answer to what space expands into.

Finally, notice that it is impossible to go south of the south pole: there is no 'before the south pole'. This is analogous to there being no 'before the Big Bang'. This is a geometrical aspect of this particular universe of spacetime.

I have other analogies along this line, but his one handles many questions many people have. I hope it helps.

Professor Sir Roger Penrose, a Nobel lauerate, has a model of an eternal Universe based upon General Relativity:

Wikipedia -- Conformal cyclic cosmology

[polymath257]

When cosmologists speak of the universe being finite or infinite, they usually mean in spatial extent using a comoving frame.

In the classical version of general relativity, there were three options: either space is positively curved (like a sphere) and time is finite in both directions, space is flat (like a plane) and time is infinite into the future but not the past, or space is negatively curved (like a saddle) and time is infinite into the future and not into the past.

Which of the three possibilities actually occurs depends on the density of matter and energy: a higher density leads to more gravity and an eventual collapse associated with the positive curvature. Less density leads to negative curvature and expansion forever. A critical density leads to flatness (and, yes, expansion forever).

This whole description became more complicated with the discovery of dark energy (also known as the cosmological constant). Einstein had originally introduced this notion as a way of having a static universe but it was discarded (except for graduate student exercises) after the expansion of the universe was discovered.

I won't go into specifics, but the nice trichotomy above is shifted and it is possible to have expansion forever even if the universe is positively curved.

Anyway, in anything based on general relativity and NO quantum mechanics, the universe is finite into the past.

The question of what the universe is expanding into is a subtle one and requires a bit different perspective.

In modern cosmology, we discuss the geometry of spacetime, not just of space itself or time itself. The two together form the basic geometry of the universe. So when a cosmologists models the universe, they model it throughout both space and time as a single object. All dynamics occur within this object at different time slices.

So, as an analogy, I'm going to describe a 'universe' that is one dimensional in space and one dimensional in time and that is also curved in spacetime.

Imagine a globe. Imagine the latitude of a point describes the time and the longitude describes the spatial location. The two together will characterize the point. We imagine points further south are previous to those further north.

Space is then the collection of points at a particular time: this corresponds to a latitude line.

Now, starting at the 'beginning' of the south pole (more about this later), the latitude lines get larger as we approach the equator: in other words, space is expanding as we move forward in time. At the equator, we have maximum expansion, and then space begins to contract until we get to the end (the north pole).

So, looking at this analogy: what does space expand into?

The answer, literally and geometrically, is *the future*. And that is the answer to what space expands into.

Finally, notice that it is impossible to go south of the south pole: there is no 'before the south pole'. This is analogous to there being no 'before the Big Bang'. This is a geometrical aspect of this particular universe of spacetime.

I have other analogies along this line, but his one handles many questions many people have. I hope it helps.

Professor Sir Roger Penrose, a Nobel lauerate, has a model of an eternal Universe based upon General Relativity:

Wikipedia -- Conformal cyclic cosmology

Which does have some appeal, I admit.

Still, we *know* that quantum gravity effects will be relevant at some point, so this type of splicing together may not be as straightforward as it appears in just GR.

[Jehanne]

Professor Sir Roger Penrose, a Nobel lauerate, has a model of an eternal Universe based upon General Relativity:

Wikipedia -- Conformal cyclic cosmology

Which does have some appeal, I admit.

Still, we *know* that quantum gravity effects will be relevant at some point, so this type of splicing together may not be as straightforward as it appears in just GR.

Without exception, every theorist that I have read, in popular, undergraduate (mostly) and graduate (a few) texts all agree that General Relativity is not the complete picture, and certainly not the final one.

[JairCrawford]

Professor Sir Roger Penrose, a Nobel lauerate, has a model of an eternal Universe based upon General Relativity:

Wikipedia -- Conformal cyclic cosmology

Which does have some appeal, I admit.

Still, we *know* that quantum gravity effects will be relevant at some point, so this type of splicing together may not be as straightforward as it appears in just GR.

Do you think something like the graviton could be the answer? Is there potential to discover a graviton at the LHC like we did with the Higgs boson?

[Jehanne]

Which does have some appeal, I admit.

Still, we *know* that quantum gravity effects will be relevant at some point, so this type of splicing together may not be as straightforward as it appears in just GR.

Do you think something like the graviton could be the answer? Is there potential to discover a graviton at the LHC like we did with the Higgs boson?

You're missing the point of Science entirely (at least in my opinion). Scientists develop models that describe nature and they continue to develop and test those models in search of better and better models, ad infinitum.

Seriously, you need to start with freshmen physics and go from there. The last chapter of Halliday, Resnick and Walker will give you the introduction to cosmology. If you want to understand General Relativity, you'll need to go to graduate school.

[JairCrawford]

Do you think something like the graviton could be the answer? Is there potential to discover a graviton at the LHC like we did with the Higgs boson?

You're missing the point of Science entirely (at least in my opinion). Scientists develop models that describe nature and they continue to develop and test those models in search of better and better models, ad infinitum.

Seriously, you need to start with freshmen physics and go from there. The last chapter of Halliday, Resnick and Walker will give you the introduction to cosmology. If you want to understand General Relativity, you'll need to go to graduate school.

I’m not sure how the potential (or lack thereof) of a discovery of a graviton is an unscientific question to ask? If the question is totally implausible due to the math, then just tell me. I’m going to have to take your word for it because I know my limitations when it comes to understanding complex math, which is why Im not about to try to do all of those things lol. I was reading the Wikipedia page for quantum field theory and the math formulas they showed might as well have been a foreign language. Again, I know my minds limits there. But such limitations do not quench my curiosity. I strive to understand as best as I can, in layman’s terms, despite my mathematical limitations.

Also I understand that question is very much a what-if. I know that science is about making observations and what-ifs are really just what-ifs. But at the same time, the graviton has been hypothesized for a while so I’m just curious if that would help answer questions about quantum gravity. I’m not, however, banking on it being “true until proven false” or anything like that because that would be blatantly unscientific.

[Jehanne]

I think that you would be best served by reading more Wikipedia articles; here's one on the expansion of the Universe:

Wikipedia -- Expansion of the Universe

As for the graviton, it's a hypothetical particle.  If it exists, it must be a spin-2 particle.

[polymath257]

Which does have some appeal, I admit.

Still, we *know* that quantum gravity effects will be relevant at some point, so this type of splicing together may not be as straightforward as it appears in just GR.

Do you think something like the graviton could be the answer? Is there potential to discover a graviton at the LHC like we did with the Higgs boson?

In quantum theory, every wave phenomenon has a particle aspect to it (wave/particle duality) and vice versa.

We know gravitational waves exist, so there should be a corresponding particle. That particle is the graviton.

The problem is that the waves we have been able to detect correspond to very low energy gravitons and many, many of them. So it is impossible for us to detect a single graviton in this way. But, to get to the high energies required to be able to do this, we would have to get particle energies *far* higher than anything the LHC can produce (by many several of magnitude).

So, no, there is no potential to find gravitons at the LHC: the energies required are just too high. All energies at the LHC are still well within the range of classical gravity (a la general relativity).

Getting a good theory of the graviton is essentially the same thing as getting a good theory of quantum gravity. And yes, that is what we need to answer some fundamental questions.

When I was young, the unification of gravity and quantum mechanics was a BIG unsolved problem. Now, we at least have some theories that manage to merge the two. The problem is that we have no way to get to the energies required to test them and the different models give different answers to questions we are curious about.

So, we just don't know.

[The Grand Nudger]

Let's say it didn't. Then what? Amazing, right? Something else happened, that only seemed to lay a mound of evidence behind it for that thing.