How was the universe created?

An artist's conception of the Big Bang birthing multiple galaxies. (Image credit: Mark Garlick/Science Photo Library/Getty Images)

We know that we live in an expanding universe. That means the entire universe is getting bigger with every passing day. It also means that in the past our universe was smaller than it is today.

Rewind that tape far enough, and the physics suggests our universe was once an infinitely tiny, infinitely dense point — a singularity.

Most physicists think this point expanded out in the Big Bang, but because all known physics breaks down in the extreme conditions that prevailed in our universe's infancy, it's hard to say with confidence what happened in those earliest moments of the universe.

Going back in time

For most of the history of the universe, it was dotted with similar celestial objects as are present now — they were just closer together.

For example, when our universe was less than 380,000 years old, the volume of the universe was about a million times smaller than it is today, and it had an average temperature of around 10,000 Kelvin. It was so hot and dense that it was a plasma, a state of matter where atoms are ripped apart into protons, neutrons and electrons. However, we encounter plasmas in many other situations in space and on Earth, so we have a pretty good understanding of how they work.

But the farther back we go, the more complex the physics become. When the universe was just a dozen minutes old, it was an intense soup of protons, neutrons, and electrons, still governed by the same physics that we use to understand nuclear bombs and nuclear reactors.

If we look back even earlier than that, however, things get really sketchy.

When we try to make sense of the universe when it was less than a second old, we have no theory of physics that can cope with the insanely high temperatures and pressures the universe experienced. All of our theories of physics break down, and we have no understanding of how particles, forces and fields operate in those conditions.

Birthing the singularity

Physicists can chart the growth of the cosmos using Einstein's general theory of relativity, which connects the content of the cosmos to its history of expansion.

But Einstein's theory contains a fatal flaw. If we follow general relativity to its ultimate conclusion, then at a finite time in the past our entire universe was crammed into a single, infinitely dense point. This is known as the Big Bang singularity.

The singularity is often framed as the "beginning" of the universe: But it's not a beginning at all.

Mathematically, the singularity at the Big Bang isn't telling us that the universe began there. Instead, it's telling us that general relativity itself has broken down, and has lost its predictive and explanatory power.

Physicists have long known that general relativity is incomplete. It cannot explain gravity at high strength or at small scales, known as quantum gravity. In other words, to fully understand the earliest moments of the universe, we need new physics.

This graphic shows a timeline of the universe based on the Big Bang theory and inflation models. (Image credit: NASA/WMAP)

A question for the ages

Sadly, we currently lack such physics. We have several candidates for quantum gravity, like string theory and loop quantum gravity, but these theories have not been fully developed, let alone tested.

But if either of those theories are correct, they can tell us interesting things about the early universe.

— The Big Bang: What really happened at our universe's birth?

— How does time work?

In the case of loop quantum gravity, the singularity is replaced with a finite-size chunk of space-time. In string theory, meanwhile, our universe originates from a "landscape" of possible universes. It's also possible that our Big Bang exists as just one of an infinite series of universes, multiplying without end in a multiverse. Only further advances in theoretical physics will help sort out the murkiness of these possible ideas.

But there's another problem: We may never know what caused the Big Bang. In its earliest moments, even our very conceptions of time and space break down. At such extreme scales, normal, everyday concepts like "beginning" and "before" may not even make sense.

Originally published on LiveScience.

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community@space.com.

Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute in New York City. Paul received his PhD in Physics from the University of Illinois at Urbana-Champaign in 2011, and spent three years at the Paris Institute of Astrophysics, followed by a research fellowship in Trieste, Italy, His research focuses on many diverse topics, from the emptiest regions of the universe to the earliest moments of the Big Bang to the hunt for the first stars. As an "Agent to the Stars," Paul has passionately engaged the public in science outreach for several years. He is the host of the popular "Ask a Spaceman!" podcast, author of "Your Place in the Universe" and "How to Die in Space" and he frequently appears on TV — including on The Weather Channel, for which he serves as Official Space Specialist.

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9 Comments Comment from the forums

Helio

There are some points worth addressing in this article, though it does a nice nice summary job.

The time of the CMBR is the 380,000 years stated, which would have been at 3,000K, not the stated 10,000K.

There should be, IMO, statements that help us delineate math from actual physics.
The LHC is only capable of addressing the physical nature, perhaps to a reasonable degree, of the state of the universe when it was a trillionth of a second old, but nothing sooner. This is as close as we have gotten to a supposed (not hypothetical since no test is possible even in principle) singularity.

I did like this statement, "Mathematically, the singularity at the Big Bang isn't telling us that the universe began there. Instead, it's telling us that general relativity itself has broken down, and has lost its predictive and explanatory power. " This expresses some of the difference between math and physics. But, given that the first solution to GR was that of a black hole, I wish I could understand the difference between a little BH and the supposed beginning singularity, as far as why the math gives GR an "F" grade.
Reply
Unclear Engineer

I think the "F" grade for the singularity is consistent with "black holes" in that GR does not work at the event horizon nor the singularity of the BBT. Yes, there are mathematical solutions inside the event horizon, but how would we be able to see if those solutions are real?

It still seems to me that GRT "breaks down" well before we have extrapolated the whole universe back into a tiny point, much less a singularity. The problem is that the mass of the universe, when compacted even slightly more than it is now, would be inside its own event horizon, so should be collapsing, not expanding with time. That is why "inflation" was added to the BBT to make space itself expand, so that the matter of the universe does not need to have traveled through space at more than the speed of light to have expanded from what we have backwards-extrapolated the currently observed expansion to have started from.

But "inflation" is just one of those things about the BBT that theorists assume must have happened because that is all they can think of that would make their backwards extrapolation capable of having been a real expansion in the past.

What makes inflation actually work is not understood. There are theories, but none proven. Same problem with "dark energy" that is theorized to be accelerating the expansion again, now.

For me, when things like "inflation" are added to the GRT, I look for more than just making the model fit the observations. I ask questions such as:

1. If we live in a 4-dimensional universe called space/time, and we assume that the 3 physical dimensions can expand and contract, why are we not also considering that time could have expanded (or contracted) as space inflated?

2. If "space" does "inflate" and can thereby move masses apart, even at more than the speed of light, doesn't that mean that mass somehow "sticks" to "space"? Would the speed of light through space tell us anything about how "sticky" space is? I am thinking of the analogy of bow waves of ships in water creating a limiting hull speed or shock waves in air from airplanes moving faster than the speed of sound. Somewhat similarly, particles with non-zero rest mass that are traveling at more than the speed of light in other matter release photons and slow down - is this the equivalent of a sonic boom shock wave, but in electromatignetic fields? Would "inflation" have created similar shock waves as it dragged matter that was somewhat resisting the drag force?

3. "Frame dragging" effects described by the GRT, which have moving mass dragging "space" along with it, are another thing that seems to be necessary to consider with "inflation" when we start trying to explain a "Big Bang" beginning to what we now observe. If space inflated, would the matter in it have simpley separated by the same amount, or would space have had to "drag" the resisting matter the same way that moving matter "drags space", so that the matter did not move as far as the space moved? And the corrolary is to ask if light gets moved differently than matter by "inflation" or other expansions of space.

4. And, when "space" expands, does that expand the dimesions of the things in space? Do atoms get bigger? Do photons get bigger? How about answering those questions using the wave theory of matter and phtons, and then again with the theory of particles for matter and photons, and do the results of those 2 interpetations come out the same?

I feel like the believers in the BBT need to address those questions, or at least admit that they are worth asking. Trying to dodge them by claiming they "don't make sense" and saying that asking them is "like asking what is north of the north pole" misses the point that asking that about the north pole reveals that the Earths surface is curved and calls into question the definition of "north" in 3-dimensional flat space compared to 2-dimensional curved space.
Reply
billslugg

"I wish I could understand the difference between a little BH and the supposed beginning singularity, as far as why the math gives GR an "F" grade." Helio

I googled "why didn't the Big Bank instantly devolve into a black hole?" and the answer I found was that the Schwartzchild Radius is based on a static system. The BB began with considerable internal pressure to overcome the gravity.

The math gives GR an "F" as we go back prior to 10^-35s due to each particle is its own black hole thus cannot communicate with each other. Extrapolating to earlier times is fruitless since the individual particles cannot communicate in order to get hotter.
Reply
Unclear Engineer

billslugg said:
the answer I found was that the Schwartzchild Radius is based on a static system. The BB began with considerable internal pressure to overcome the gravity.

I see "answers" like that posted, too. But, those are not really answers, they are really just quibbles with the question.
"Answers" like that implicitly assume that internal pressure or pre-existing outward momentum can make matter escape a black hole. But, GRT says that there is no speed that matter can achieve that will allow it to escape from a black hole.

So that anwer is what should be graded with an "F".

The BB theorists answer is "Inflation moved space itself (and matter with it) in a manner that overcomes the limitations of GRT." (The GRT only limits the speed of matter and light through space.)

And the implications of that BBT assumption are what prompts my questions in my previous post.
Reply
rod

I pass along my observations here. During inflation, space expands some 10^21 c or faster.
https://www.scientificamerican.com/custom-media/biggest-questions-in-science/the-founder-of-cosmic-inflation-theory-on-cosmologys-next-big-ideas/
What was the size of the universe when inflation began? “A typical GUT-scale inflationary model would include about 60 e-folds of inflation, expanding by a factor of e^60 ≈ 10^26. From the end of inflation to today the universe would expand by another factor of ∼ 10^15 GeV/3K ≈ 10^27. This means that a distance scale of 1 m today corresponds to a length of only about 10^−53 m at the start of inflation, 18 orders of magnitude smaller than the Planck length (∼ 10^−35 m).” ref - https://ui.adsabs.harvard.edu/abs/2013arXiv1312.7340G/abstract
Inflation starts in a universe 10^-53 m size, 18 order of magnitudes smaller than the Planck length. Using the cosmology calculators, the CMBR z = 1100 today, and H0 = 67 km/s/Mpc - 73 km/s/Mpc. The universe radius when the CMBR appears as light is some 39-42 million light years so diameter some 78-84 million light years. Space expands from inflation size (10^-53 m) to some 80 million light years or so in diameter in 380,000 years when CMBR becomes light. Space expands many times faster than c velocity to create the universe astronomy sees today, according to BB model and inflation model. Basic origin of the universe ideas like what I documented, should not be overlooked when telling the public, how science explains the creation of the universe. In nature today, we see no such universe with such small sizes and experimental evidence confirming space expands faster than c velocity is lacking or even perhaps that space is expanding when using H0 converted to c.g.s. units ~ 10^-18 cm/s/cm.

See discussion in the forums, https://forums.space.com/threads/confirmed-james-webb-space-telescope-has-bagged-the-oldest-known-galaxies.59123/
concerning space expanding and differences between doppler redshift and the cosmological redshift model.
Reply
rod

I did like this article by space.com. I note statements like this in the report.

"Going back in time For most of the history of the universe, it was dotted with similar celestial objects as are present now — they were just closer together. For example, when our universe was less than 380,000 years old, the volume of the universe was about a million times smaller than it is today, and it had an average temperature of around 10,000 Kelvin. It was so hot and dense that it was a plasma, a state of matter where atoms are ripped apart into protons, neutrons and electrons. However, we encounter plasmas in many other situations in space and on Earth, so we have a pretty good understanding of how they work. But the farther back we go, the more complex the physics become. When the universe was just a dozen minutes old, it was an intense soup of protons, neutrons, and electrons, still governed by the same physics that we use to understand nuclear bombs and nuclear reactors. If we look back even earlier than that, however, things get really sketchy. When we try to make sense of the universe when it was less than a second old, we have no theory of physics that can cope with the insanely high temperatures and pressures the universe experienced. All of our theories of physics break down, and we have no understanding of how particles, forces and fields operate in those conditions."

Interesting. If you go back before 1 second after the postulated BB event, you run into the math of inflation and very tiny universe size, smaller than an electron at the beginning (assuming you avoid GR singularity). We have other reports that show the universe is said to be a quark-gluon plasma during 10^-6 second or earlier after the BB event. See https://forums.space.com/threads/quarks-what-are-they.58460/
It does seem in the cosmology department; folks enjoy going back well before 1 second time mark in the BB model. Without such extrapolations, the appearance of the cosmic fireball said to be the CMBR we see today has no explanation for its origin. Suddenly and mysteriously the CMBR light just appears :) I like to remember when I read these scientific creation stories that the universe started out in an area smaller than an electron and expanded to a radius of some 40 million light years or slightly larger in 380,000 years. Space expands more than 100 x c velocity in the creation model presented to the public to explain the CMBR observed today. Cosmology concepts like this should be clearly presented to the public.
Reply
Helio

Unclear Engineer said:
I think the "F" grade for the singularity is consistent with "black holes" in that GR does not work at the event horizon nor the singularity of the BBT. Yes, there are mathematical solutions inside the event horizon, but how would we be able to see if those solutions are real?
I have assumed that GR does a fine job at the EH -- Schwarzschild simply kept pushing GR to reach the escape velocity of light. But inside the EH, it becomes far more challenging to introduce any hypothesis that can be tested to strongly state what happens inside, no doubt.

It still seems to me that GRT "breaks down" well before we have extrapolated the whole universe back into a tiny point, much less a singularity.
I'm guessing whatever determines the Planck unit of time does an effective job of creating nightmares in this math. The equations reportedly shoot off into infinity at this point in time.; "the wheels go flying off the cart."

But "inflation" is just one of those things about the BBT that theorists assume must have happened because that is all they can think of that would make their backwards extrapolation capable of having been a real expansion in the past.
Yes but Inflation provides such a great answer to the problem, but even this solution fails at t=0, I think.

From Hougton's book, George Gamow presented a great model for BBT where the infant universe was complete energy, namely radiation. But it seems he hit a "brick wall" when very close to t=0.

Along came Guth and Linde and took it further (ie Inflation) by substituting a powerful quantum particle for radiation. This gave them negative gravity that went nuts for about 1e-35 sec. when radiation emerged. The quantum wave functions had a host of wavelengths so that the shorter ones produced matter such as protons.

Additional expansion stretched the wavelength of those wave/particles otherwise electrons, etc. would be very much larger than we see today.

What makes inflation actually work is not understood. There are theories, but none proven.
I hope you don't mind it when I claim that science doesn't present theories that are provable, but falsifiable. Titus-Bode was so well liked that made it a law, until Neptune was discovered and falsified it.

2. If "space" does "inflate" and can thereby move masses apart, even at more than the speed of light, doesn't that mean that mass somehow "sticks" to "space"?
The amount of mass of a particle determines its motion through space. So I don't think it sticks to space, if I understand your question.

Would the speed of light through space tell us anything about how "sticky" space is? I am thinking of the analogy of bow waves of ships in water creating a limiting hull speed or shock waves in air from airplanes moving faster than the speed of sound.
I too have wondered about this. Using your analogy, I have wondered if photons are more like hydroplanes, or like speed boats, where the entire hull is above the water (spacetime) and without interaction. Thus, very fast boats would interact less and less with both space and time allowing very short times to other planets. But the math fails since this involves an absolute version of space, so relativity opposes such a view, as far as I can tell.

Somewhat similarly, particles with non-zero rest mass that are traveling at more than the speed of light in other matter release photons and slow down - is this the equivalent of a sonic boom shock wave, but in electromatignetic fields?
Finally an actually "bang"! I would suspect those particles would not have those speeds relative to what has become known as the Hubble Flow, when these particles first emerged after the Inflation period.

4. And, when "space" expands, does that expand the dimesions of the things in space? Do atoms get bigger? Do photons get bigger?
Strangely, some would say yes.
I see the DE force today as a force vector. It is very weak for small things like stellar systems, or even galaxies. Perhaps our planet is several inches wider in its orbit, but the gravitational force, for a change :), is a far greater force. The much stronger EM force likely laughs at the DE force, but this could change in a trillion years. ;)
Reply
Helio

Unclear Engineer said:
"Answers" like that implicitly assume that internal pressure or pre-existing outward momentum can make matter escape a black hole. But, GRT says that there is no speed that matter can achieve that will allow it to escape from a black hole.
There were opponents to Einstein's GR, but when tests can take it to 15 decimal places, it's not hard to find it, at the least, extremely valuable and effective. Pushing its limits at every facet is what good science does. If one can find it false at any corner, a Nobel may await that person.
Reply
Helio

rod said:
I pass along my observations here. During inflation, space expands some 10^21 c or faster.
https://www.scientificamerican.com/custom-media/biggest-questions-in-science/the-founder-of-cosmic-inflation-theory-on-cosmologys-next-big-ideas/
What was the size of the universe when inflation began? “A typical GUT-scale inflationary model would include about 60 e-folds of inflation, expanding by a factor of e^60 ≈ 10^26. From the end of inflation to today the universe would expand by another factor of ∼ 10^15 GeV/3K ≈ 10^27. This means that a distance scale of 1 m today corresponds to a length of only about 10^−53 m at the start of inflation, 18 orders of magnitude smaller than the Planck length (∼ 10^−35 m).” ref - https://ui.adsabs.harvard.edu/abs/2013arXiv1312.7340G/abstract
Yes, the book I mentioned above shows about 20 orders. FWIW, this is also about the increase in rotation from a cloud to a protostar. The gentle rotation of the cloud takes the star's surface speed < c.
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