There was no big bang singularity

When we look at the Universe today, we see that it is full of galaxies in all directions and over a wide variety of distances. On average, we also find that the further away a galaxy is, the faster it seems to move away from us. However, this is not due to the actual movements of individual galaxies across the space; This is due to the fact that the fabric of space itself is expanding.

Prediction from General Relativity in 1922 by Alexander Friedmann, and confirmed by the work of Edwin Hubble and others in the 1920s. This means that as time pbades, the material in it expands and becomes less dense, as the volume of the Universe increases. It also means that, if we look at the past, the Universe was denser, warmer and more uniform.

If you were to extrapolate more and more far in time, you would start to notice some big changes to the Universe. In particular:

• you would come to a time when gravitation did not have time to bring matter back into clusters big enough to have stars and galaxies,
• would you come to a place where Universe was so hot we could not form neutral atoms, then even atomic nuclei
• where matter-antimatter pairs would form spontaneously
• and where protons and individual neutrons would dissociate into quarks and gluons.

Each step represents the Universe when it was younger, smaller, denser, and warmer. Finally, if you continued to extrapolate, you would see these densities and temperatures rise to infinite values, because all the matter and all the energy of the Universe were contained in a single point: a singularity. The hot Big Bang, such as it was designed for the first time, was not just a hot, dense and expanding state, but represented a moment where the laws of physics were collapsing. . It was the birth of space and time: a way to spontaneously reveal the entire universe. It was the ultimate act of creation: the singularity badociated with the Big Bang.

Yet, if that were correct, and the Universe had reached arbitrarily high temperatures in the past, there would be a number of clear signatures of what we could observe today. There would be temperature fluctuations in the glow of the remains of the Big Bang that would have extremely large amplitudes. The fluctuations we see would be limited by the speed of light; they would appear only at scales of the cosmic horizon and smaller. There would be cosmic relics of high energy and remnants of the past, like magnetic monopolies.

And yet, temperature fluctuations are only one part out of 30,000, thousands of times smaller than the singular predictions of the Big Bang. The fluctuations of the superhorizons are real, confirmed by WMAP and Planck. And the constraints on magnetic monopoles and other ultra-high energy relics are incredibly tight. These missing signatures have a huge implication: the Universe never reached these arbitrarily large temperatures.

Instead, there had to be a break. We can not extrapolate arbitrarily far, to a hot-and-dense state that reaches all the energies we can dream of. There is a limit to how far we can go and still describe our universe. In the early 1980s, it was theorized that before our universe was hot, dense, expanding, cooling, and full of matter and radiation, it swelled. A phase of cosmic inflation would mean that the Universe was:

• filled with energy inherent in space itself,
• which causes rapid exponential expansion,
• which extends on the Universe,
• gives it the same properties everywhere,
• with quantum fluctuations of small amplitude,
• which extend to all scales (even super -horizontal),

then inflation comes to an end

When he does, he converts this energy, which was previously inherent to the space itself, into matter and radiation, leading to the hot Big Bang. But this does not lead to an arbitrarily hot Big Bang, but rather to a maximum temperature that is at most hundreds of times less than the scale at which a singularity could emerge. In other words, this leads to a hot Big Bang that arises from an inflationary state, and not from a singularity.

The information that exists in our observable Universe, which we can access and measure, only corresponds to the last ~ 10 ^-33 second of inflation, and all what comes next. If you want to know how long inflation has lasted, we simply do not have a clue. It lasted at least a little longer than 10 ^-33 seconds, but it lasts a little longer, much longer or for an infinite duration is not only unknown,

. There is a great deal of research and speculation about this, but nobody knows it. There is no evidence that we can point to; no observations we can make; no experience we can perform. Some people (wrongly) say something like:

Well, we had a Big Bang singularity that gave birth to the warm, dense and expanding Universe before we knew about inflation, and inflation is only an intermediate step. Therefore, it goes: singularity, inflation, then the hot Big Bang.

There are even very famous graphics published by the best cosmologists who illustrate this image. But that does not mean it's right.

In fact, there are very good reasons to believe that this is not fair! One thing we can mathematically demonstrate, in fact, is that it is impossible for a swelling state to emerge from a singularity. Here's why: Space is growing at an exponential rate during inflation. Think of the operation of an exponential: after a while, the Universe doubles its size. Wait twice as long and double twice, which is four times bigger. Wait three times longer, double three times, which is 8 times bigger. And if you wait 10 or 100 times longer, these doublings make the Universe 2 ¹⁰ or 2 ¹⁰⁰ times larger.

Which means that if we go back in time the same amount, or twice, or three times, or 10 or 100 times, the Universe would be smaller, but would never reach a size of 0. Respectively, it would be half, a quarter, an eighth, 2 ^-10 or 2 ^-100 times its original size. But no matter where you go, you'll never get a singularity.

There is a theorem, famous among cosmologists, that shows that an inflationary state is past – temporal – incomplete. What this means, explicitly, is that if you have particles that exist in a swelling Universe, they will eventually meet if you extrapolate in time. This does not mean however that there has been a singularity, but rather that inflation does not describe everything that has happened in the history of the Universe, as His birth. We also know, for example, that inflation can come from a singular state because an inflation region must always start from a finite size.

Whenever you see a diagram, an article or a telling story about the "singularity of big bang" big bang / singularity existing before inflation, know that you are dealing with an outdated method of thinking. The idea of ​​a Big Bang singularity came out of the window as soon as we realized that we had a different state – that of cosmic inflation – preceding and setting up the early state , hot and dense of the Big Bang. There may have been a singularity at the very beginning of space and time, with the resulting inflation, but there is no guarantee. In science, there are things that we can test, measure, predict and confirm or refute, like an inflationary state giving rise to a burning Big Bang. Everything else? This is nothing more than speculation.

Discover some additional information on the (lack of) Big Bang Singularity The Last Starts With A Bang Podcast

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Almost everyone has heard the story of the Big Bang, but if you ask someone, from a layman to a cosmologist, to finish the following sentence : "At first there was …" get a series of different answers One of the most common is "a singularity", which designates a moment where all the matter and all the energy of the & # 39; Universes were concentrated in a single point: the temperatures, densities and energies of the Universe would be arbitrarily, infinitely large, and could even coincide with the birth of time and space itself.

But this image is not only wrong, it is almost 40 years old! We are absolutely certain that there was no singularity badociated with the hot Big Bang, and there was not even a birth to space and time. Here is what we know and how we know it.