Do I understand the Big Bang?

Please correct all my mistakes in my understanding of the this event.

  1. The Big Bang happened about 13.7 billion years ago. This has been confirmed by two independent studies.
  2. The Big Bang created the universe and everything in it. There is absolutely no way to ever know what was before the Big Bang.
  3. The Big Bang was a quantum fluke that created matter out of nothing. It created equal amounts of matter and antimatter.
  4. Due to another quantum fluke, more matter survived than antimatter.
  5. While the expansion was homogeneous, quantum randomness brought material together and gravity took over, creating stars, galaxies etc.
  6. The fundamental forces of nature are finely tuned allowing matter to exist. If these forces were slightly different, the universe would not exist.

Finally a question
If there was nothing before the Big Bang and all time and space was created at that time, could universe be created inside our own universe, where time a space already exist?

Tha nks

  1. From where did you learn this, and
  2. What two independent studies are you referring to?

Regarding 2: There are a lot more than two “independent studies” backing up the Big Bang. A lot more.

Regarding 3: Things have to be qualified. I.e.: Per our current knowledge of Physics we do not “know what was before the Big Bang.”

But there are several ideas about what what was going on and how it happened. E.g., there was this recent announcement. Which is not really mainstream but not so odd as to be completely written off as woo.

And the whole matter vs. antimatter thing is still pretty much up in the air.

For point 3, Lawrence Krauss wrote a book about how the positive energy of matter and the negative energy of gravity cancel each other out, making our universe a zero energy state. He claims this is why the universe arose out of nothing and that it could happen all the time.

As far as point 6, I wonder if the finely tuned universe can be used to make the argument for a multiverse. The odds that the cosmological constants are exactly right to allow for complex chemistry are infinitely small. If there were only one universe, the odds are tiny.

Correct, except that it is supported by more than just two studies. I think you are probably referring to the Wilkinson Microwave Anisotropy Probe (WMAP) and the Planck microwave space observatory, both of which study the cosmic microwave background (CMB) which is often referred to as an echo of the Big Bang, or more precisely the first light emitted when the universe expanded and cooled sufficiently to be transparent. These and other observed data support the current concordance model of the composition and distribution of matter and energy in the universe called the Lambda-Cold Dark Matter (ΛCDM) model.

In a sense, this is true. The matter and energy that emerged from the singularity technically pre-existed the event of the Big Bang, but beyond that we cannot say from where it came or what form it took prior to emerging from the singularity. There are some speculative notions about where our universe came from but nothing that can be falsified by observation or experiment, and unless we find evidence of gravitational radiation from outside of our universe it seems likely we will never be able to make a clear determination of this question.

Not really, and no. It is true that baryonic matter emerged from combinations of energy (baryogenesis) following a electroweak symmetry breaking and the quark epoch, after which hadrons could form. However, that matter was produced from previously existing energy, not “nothing”. Even virtual particles (those that hypothetically spontaneously come into existence through fluctuations in the vacuum energy and then disappear) don’t come from “nothing” but rather then baseline “vacuum” energy that exists as a consequence of Heisenberg’s indeterminacy principle. There was clearly slightly more matter than antimatter because nearly all matter we see today is normal matter with only trace amounts of antimatter being spontaneously produced by highly energetic phenomena. Unless someone is hiding a whole antimatter universe somewhere else, our universe is matter dominated, and specifically by so-called “dark matter” that seems to only interact with weak and gravitational forces.

It is unknown why there is more normal matter than antimatter; this is one of the great puzzles of modern cosmology.

It is unknown why large scale cosmic structures (sheets, walls, filaments, and superclusters) formed. There are many hypotheses but nothing that is actually testable. The distribution of the CMB of the universe was measured by the two satellite missions listed above (Planck and WMAP) and have provided hard limits on the degree of anisotropy that could occur, but we don’t know that the expansion of spacetime was strictly homogeneous or what may have caused gravitational fluctuations which permitted matter to clump up and form. Dark matter may have played a significant role in this but since we cannot directly observe or even understand what dark matter is we cannot draw any definitive conclusions or even state very firm hypotheses.

Sort of true. There are dimensionless physical constants which have to be in a pretty narrow range of values for the universe as we know it to exist, and other variations would not permit stars to form and fuse, or even basic chemistry as we know it to operate. However, we can only make very rough guesses about what other kinds of physics might emerge from different sets of parameters, and what scales the forces would operate at. It is certainly possible that our universe is just one of countless and potentially infinite numbers of universes being spontaneously formed, and so our particular formation and the ability to create a self-aware consciousness to examine and explore it may not be surprising but actually inevitable.

Possibly. Black holes, which are systems in which matter has compressed to such a high density that the escape speed exceeds that of c, meaning that information cannot escape, could be the nuclei seeding new universes within our own, and in fact the Big Bang looks very much like a black hole in reverse (i.e. a “white hole” of matter spewing forth from a singularity). Because of this barrier between our universe and what goes on within the absolute horizon (also referred to as the “event horizon”) we cannot say anything about what goes on within a black hole or what the resulting physics might look like; it could possibly inherit properties of our universe, or produce completely unique and different properties and force interactions. There are some theoretical possibilities for “transversible” black holes or “naked” singularities but there is no evidence that these do actually exist in nature or could be manufactured without using some kind of “exotic” negative energy density matter which we do not know to even exist.

Although you did not state this common conceptual error, it should be noted that the “Big Bang” was not just a spewing of matter and energy into previously empty space, but an actual expansion of spacetime itself, hence why the observable universe is over 46 Blyr away even though the age of the universe is only 13.7 Byr of age; although energy and matter can only move at or less than c, spacetime can expand faster, and in fact has been accelerating as the universe has gotten older, and it is believed will continue to do so unless a new mechanism comes along to reverse it.


I am referring specifically to the age of universe. More correctly it is 13.8 billion years old. The first method involves studying cosmic microwave radiation and the second involve reversing the expansion rates of celestial objects.

3.) Has always annoyed the crap out of me. I don’t blame the OP for thinking that, because this is due in part to space documentaries trying to dumb it down to much for the lay person.

Thanks for clearing that up Stranger.

Going back to #3.
The universe did not arise out of nothing but out of previous energy. Is this correct?
It would make sense because of the basic principle that something can’t arise out of nothing.
I think Stranger is saying that the mechanism of matter formation after the Big Bang is well understood but the nature of the energy that gave birth to that matter is not understood at all. Right?

We have a problem here with language. English is useful for describing things that happen, cause and effect, past and future. But all that breaks down at the moment of the Big Bang. We know what happened after the Big Bang, when time was moving forward and effects were following from causes. But asking what happened before the Big Bang is like asking what’s north of the North Pole. The question itself doesn’t make sense. The word “before” can’t apply to a situation where time hasn’t started yet. For that matter, the word “happened” can’t apply either.

Our experience doesn’t help us here. We never experience in nature, and can never duplicate in the lab, a situation where time does not exist and “then” some"thing" may or may not “happen”. People say they can’t understand how nothing became something. But the word “became” implies before and after, which implies time, which did not exist before the Big Bang.

I also heard a very pithy response to people who make pronouncements about nothingness and what it can’t do. “Show me some nothingness and let me examine it to determine if you’re right.”

As for part 6 of the OP, it may turn out that the fundamental constants of the universe are not subject to change but they are in fact dependent on each other. Consider this. Stand halfway between a light source and a wall. What is the ratio of the height of the shadow to the height of you? It’s two. Okay, now show me a universe where it’s 1.9 instead. Is that possible? I don’t know. The same is true of the relationship between the strong nuclear force and the weak nuclear force. Maybe one depends on the other. We don’t know. People are always asking what would happen if we change this or that or the other thing without changing anything else. And the honest answer is that we don’t know if it’s POSSIBLE to change one thing without changing anything else. We only have this one universe to observe. Maybe the universe is like math and geometry. Try as hard as you want, you can’t just decide that 2+2=5. You can’t change the fact that sqrt(10)>3. And you can’t change the fact that 3.141592653<pi<3.141592654. You can’t change the fact that Euler’s Conjecture is false despite the first counterexample requiring six digits. You can’t change the fact that all 2D maps can be colored with 4 colors or less. Maybe the universe is like that. Maybe the number of postulates and axioms is much smaller than we think.

The concept of “fine tuning” conjures up a radio operator twiddling knobs and dials. But we have no way of knowing just how many knobs there are on a universe making machine. Maybe it’s just one knob. Maybe there aren’t any knobs, just a single big red button.

It appears that you are assuming that empty space is empty when it is mostly not empty.

The vacuum at it’s lowest energy state is full of “stuff” and it actually takes massive amounts of more energy to get rid of that “stuff” to make it truly empty and it is unstable too. The average value of the fields is close to zero in this minimal energy state but “vacuum fluctuations” and “virtual particles” make this space very “full”.

I am sorry and I don’t know of a good beginners guide to what is meant by vacuum fluctuations.

The physical vacuum of space is not excited is considered empty. In an excited state it contains radiation and matter.

This is over simplified and will be hard to conceptualize but I will try. On a cosmological/astrophysical context our current understanding is that due to the Casimir effect in space-time with a non-trivial topology vacuum polarization drives the inflation process. In this theory structures arise due to topological defects producing the “stuff” we think of as matter and energy.

There are unanswered questions related to vacuum energy and the Casimir force but the important take away is to realize that there is a lot more to the universe than we intuitively consider and the portions that we are made of and we interact with are not concretely distinct like your post is suggesting.

Empty space being mostly not empty is the important part here.

A lot of this is in “we don’t know” territory, and all of the rest of it is in “to the best of our knowledge”. The most popular models hold that time itself originated with the Big Bang, and so it’s meaningless to speak of “before the Big Bang”, but there are other models where time can be extended indefinitely into the past, and the “stuff” of the Universe pre-existed the Big Bang, and it’s very difficult, maybe even impossible, to tell which model is correct.

The matter-antimatter asymmetry is firmly in “we don’t know” territory. We do know that, everywhere in the observable Universe, matter is more common than antimatter (if it weren’t, there would be some boundary between the two regions, and such a boundary would be noticeable… but we don’t notice it). And we also can’t think of any good reason why one type would be more common than the other. Maybe it started off that way, maybe it started off balanced and something later upset that balance, maybe there are antimatter regions too but they’re too far away to be within the observable Universe, we just don’t know.

As for the fine-tuning argument, you run into the problem of “as we know it”. Matter as we know it depends on certain constants being fine-tuned, but we don’t know what would happen with other values of those constants: Maybe other values would lead to something else that’s just as interesting, in its way, as our sort of matter.

So because space has energy in it, it is not empty?

Perhaps the set of very interesting universes is similar to the recently-discussed set of Liouville numbers: there may be infinitely many interesting parameter settings, but the set has tiny measure. Isn’t it widely supposed that tiny changes to elementary particle parameters would prevent useful chemistry or useful star cycles?

Zero-point energy is a complex subject that is fraught with misunderstanding and woo and is also at the edge of our current understanding but has been experimentally verified at this point.

Basically the vacuum constantly fluctuate in their energy state because of the Heisenberg uncertainty principle. This zero-point energy is significant if inaccessible to us but particles can “borrow” from this energy and so there is a very active soup of particles and anti-particles being created and destroyed in “empty space” all the time.

This principle also relates to Hawking radiation as in one form of the theory these particle/anti-particle pairs happening close to a black hole end up being on different sides of the event horizon so they don’t just borrow that energy for a small time period but kind of steal it.

PBS SpaceTime is a pretty reliable source for accessible videos on this subject so I will provide a link here on a video that may help.

I am not a physicist (any more), but there is a point about the OP which I think he understands but seems to be often confused. At least this is how I understand things.

What happened with the Big Bang is that spacetime started to grow. There was no time before the Big Bang-one can no more sensibly ask what existed before the Big Bang than one can ask what exists inside the origin of a coordinate system. 0,0 is the origin, there isn’t anything inside that. There is no time before the beginning because there is no time (because there was no spacetime before the Big Bang) before time zero.

BTW, Brian Greene in “The Fabric of the Cosmos” on p. 313 states that at the beginning of inflation, the speck of the inflaton field that gave rise to the entire universe weighed about 20 lbs. That is all it took to create all the matter and energy and spacetime that exists in the universe. Humble beginnings! :slight_smile:

And 13.8 billion years is … complicated. Not only because of all that relativity of time and time space concept, but also from subjective individual point of view. and space is 100 b. old by dog years standard … We still need a lot of wetware upgrades to understand anything.

No, the 13.8 billion years part is perfectly simple and understandable, just what it says on the tin. There are plenty of parts of this that are difficult or impossible for us mere mortals to comprehend, but that’s not one of them.

Its that number that’s the problem because it presumes as set beginning calculated in Earth years. It implies that something specific happened at that time in the past. Also,
The passage of time may not have been uniform especially in the beginning. Doesn’t this make the number arbitrary?

The only reason to not use our own clock would be to use one that is more authoritative.

Under General Relativity there are no privileged frames for us to use. There is no universal clock, and our clock is just as valid as any other clock in the universe.

That is the catch about General Relativity in general, it is all relative.

Whether two spatially separated events occur at the same time is not absolute and so one couldn’t arbitrarily choose another observer’s reference frame. The order of events or sequence of events may be different from another reference frame.

Using our clock is really the only option we have.

If you were travelling on a path very different than most of the rest of the observable universe, then your clock wouldn’t agree with their clock. But most things in the universe are traveling along at pretty close to the same speed. We don’t see stars or planets zipping past us at large fractions of the speed of light. Compared to the speed of light, the speed differences in most of the things we observe are pretty small.

That is to say, if there are astronomers on a planet orbiting a star in the Andromeda galaxy those astronomers are going to make an estimate of the age of the Universe very very close to our estimate. And this is because the matter that makes up their planet and star and galaxy hasn’t been doing much that’s different than the stuff that makes up our planet and star and galaxy.

If you were an astronomer on a planet zipping through the Milky Way galaxy at 99.99% of the speed of light, then your estimate of the age of the universe might be different than ours. But the problem is that there aren’t any such planets or stars. And the reason there aren’t is because planets and stars are formed out of clouds of gas that are sitting around in empty space, and there would have to be some force acting on them to accelerate them like that. What would that force be?