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There was no big bang singularity




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An illustration of our cosmic history from the Big Bang to the present in the context of the expanding universe.The hot big bang was a state of cosmic inflation, but the idea that everything regrettably, a singularity must be outdated. NASA / WMAP Scientist Team

Almost everyone has heard the story of the Big Bang, but if you ask somebody, from a layman to a cosmologist, to finish the sentence: "In the beginning there were …" They will get a number of different answers One of the most common is "a singularity" that refers to one At that moment all the matter and energy in the Universe focused on one single point: the Temperatures, densities, and energies of the universe would be arbitrary, infinite, and could even coincide with the birth of space and time.

But this image is not only wrong, it is almost 40 years old! Surely there was no singularity associated with the hot big bang, and maybe there was no birth at all in space and time. Here's what we know and how we know it.

The GOODS North survey shown here contains some of the most distant galaxies ever seen, many of which are already out of reach. As we look at larger and larger distances, we find that the more distant galaxies seem to be retreating faster and faster due to the expansion of the universe. NASA, ESA and Z. Levay (STScI) [19659002]

If we look at the universe today, we see that it is in all directions at a multitude of galaxy distances. On average, we also find that the farther away a galaxy is, the faster it seems to pull away from us. However, this is not due to the actual movements of the individual galaxies through space. it is due to the fact that the structure of space is expanding.

This was a prediction that was first brought out of the general relativity theory in 1922 by Alexander Friedmann and observingly confirmed by the work of Edwin Hubble and others in the 1920s. It means that matter will spread over time and become less dense as the volume of the universe increases. It also means that as we look into the past, the universe is denser, hotter and more consistent.

Extrapolating all the way back brings us to earlier, hotter and denser states. Does this lead to a singularity in which the laws of physics collapse themselves? NASA / CXC / M.Weiss

If you extrapolate back and forth in time, you would begin to notice some major changes in the universe. In particular:

  • They would come into an era when gravitation did not have enough time to pull matter into enough big piles to have stars and galaxies,
  • They would come to a place where the Universe It was so hot You could not form neutral atoms,
  • and then even atomic nuclei were blasted apart
  • where spontaneous matter-antimatter pairs formed
  • and where individual protons and neutrons would be dissociated into quarks and gluons.

In a singularity, conventional physics collapses, even when talking about the beginning of the universe. However, there are consequences for reaching arbitrarily hot, dense states in the universe, and many of them can not stand observations. © 2007-2016, Max Planck Institute for Gravitational Physics, Potsdam

Each step represents the universe as it was younger, smaller, denser, and hotter. Finally, if you continue, you would see these densities and temperatures rise to infinite values, because all matter and energy in the universe is contained in a single point: a singularity. The hot big bang, as it was first conceived, was not only a hot, dense, expanding state, but a moment when the laws of physics collapsed. It was the birth of space and time: a way to spontaneously bring the entire universe to life. It was the ultimate act of creation: the singularity associated with the Big Bang.

The stars and galaxies we see today did not always exist, and the farther we go back, the closer an apparent singularity is to the universe of this extrapolation, there is a limit. NASA, ESA, and A. Feild (STScI)

But if this were correct and the universe had reached arbitrarily high temperatures in the past, there would be a number of clear signatures of which we could observe today. There would be temperature fluctuations in the big bang of the Big Bang, which would have enormous amplitudes. The fluctuations we see would be limited by the speed of light; they would only appear on scales of the cosmic horizon and smaller. There would be leftover high-energy cosmic relics from earlier times, like magnetic monopolies.

And yet, the temperature fluctuations are only 1-part-30,000, a thousand times smaller than a single Big Bang predicts. Super Horizon fluctuations are real, both confirmed by WMAP and Planck. And the limitations for magnetic monopolies and other ultra-energy relics are incredibly narrow. These missing signatures have an immense implication: the universe never reached these arbitrarily high temperatures.

The fluctuations in the cosmic microwave background are of such small size and of such a special pattern that they strongly suggest that the universe began at the same temperature everywhere and had only 1-part-in-30,000 fluctuations, a fact which is incompatible with an arbitrarily hot big bang. ESA and the Planck Collaboration

Instead, there must have been a cutoff. We can not extrapolate back arbitrarily, 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 validly describe our universe. It was theorized in the early 1980s that before it was hot, dense, expanding, cooling, and full of matter and radiation, our universe ballooned. A phase of cosmic inflation would mean that the universe:

  • is filled with energy inherent in the space
  • which causes a rapid, exponential expansion
  • which expands the universe flatly,
  • gives it the same features everywhere
  • with small amplitude quantum fluctuations,
  • extending to all scales (even over horizontal),

and then inflation comes to an end.

Inflation allows space to expand exponentially, which can quickly cause any pre-existing curved or not-smooth space to appear flat. When the universe is curved, it has a radius of curvature at least a hundred times larger than what we can observe. E. Siegel (L); Ned Wright's Cosmology Tutorial (R)

When it does, it transforms the energy previously inherent in the space itself into matter and radiation, resulting in the Hot Big Bang. But it does not lead to an arbitrarily hot Big Bang, but to a temperature that is at most a hundred times smaller than the magnitude in which a singularity could arise. In other words, it leads to a hot big bang that comes from an inflationary state rather than a singularity.

The information that exists in our observable universe that we can access and measure corresponds only to the last ~ 10 -33 seconds of inflation and everything that came afterwards. If you want to ask how long inflation lasted, we simply have no idea. It took at least a little longer than 10 -33 seconds, but whether it took a little longer, much longer, or for an infinite amount of time is not only unknown, but unknowable.

The cosmic history of the entire known universe shows that we owe the origin of all matter in it and all light ultimately to the end of the inflation and the beginning of the hot big bang. Since then, we have had 13.8 billion years of cosmic evolution, a picture confirmed by several sources. ESA and the Planck Collaboration / E. Siegel (corrections)

So what happened to stop inflation? There is a tremendous amount of research and speculation about it, but nobody knows. There is no evidence to point to; no observations we can make; no experiments we can do. Some people (falsely) say something similar to:

Well, we had a big bang singularity that created the hot, dense, expanding universe before we knew about inflation, and inflation is only an intermediate step. That's what it's all about: singularity, inflation and then the hot big bang.

There are even some very famous graphics by top cosmologists that illustrate this picture. But that does not mean that this is right.

Illustration of the density (scalar) and gravitational wave (tensor) fluctuations that result from the end of inflation. Note that the assumption that a singularity exists before inflation is not necessarily true. National Science Foundation (NASA, JPL, Keck Foundation, Moore Foundation) – Funded BICEP2 program

There are, in fact, very good reasons to believe that this is not true! In fact, one thing we can demonstrate mathematically is that it is impossible for an inflating state to emerge from a singularity. Here is the reason: Space is expanding exponentially during inflation. Think about how an exponential works: After a while, the universe doubles. Wait twice as long and it will double twice, making it four times as big. Wait three times as long, it doubles three times, making it 8 times larger. And if you wait 10 or 100 times longer, these doublings make the universe 2 times larger 10 or 2 100 .

Which means if we go backwards in time with 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. Accordingly, it would be a half, a quarter, an eighth 2 -10 or 2 -100 times its original size. But no matter how far back you are, you never reach a singularity.

Blue and red lines represent a "traditional" Big Bang scenario in which everything begins at time t = 0, including space-time itself. In an inflationary scenario (yellow), we never reach a singularity in which the space in transitions to a singular state; instead, in the past, it can only be arbitrarily small while time goes backwards forever. The Hawking-Hartle-No-Boundary condition challenges the longevity of this state, as does the Borde-Guth-Vilenkin theorem, but none of it is certain. E. Siegel

There is a famous theorem among the cosmologists, which shows that an inflationary state is temporally incomplete. What this explicitly means is that if you have any particles in an inflating universe, they will eventually meet if you extrapolate in time. However, this does not mean that there must have been a singularity, but that inflation does not describe everything that happened in the history of the universe, such as its birth. For example, we also know that inflation can not come from a singular state, since an inflation region always has to start from a finite size.

Fluctuations of space-time even on the quantum scale are stretched during the inflation over the universe imperfections in both the density and in the gravitational waves. Whether or not inflation originated from a possible singularity is unknown. E. Siegel, with images by ESA / Planck and DoE / NASA / NSF's interinstitutional working group on CMB research

Every time you see a diagram, an article, or a story about the Big Bang singularity "or any other kind of language see big bang / singularity before inflation, know that you are dealing with an outdated mindset. The idea of ​​a Big Bang singularity came out of the window as soon as we realized that we had another state – that of cosmic inflation – that preceded and set up the early, hot, and dense state of the Big Bang. There may have been a singularity at the beginning of space and time, with inflation arising thereafter, but there is no guarantee. There are things in science that we can test, measure, predict and confirm or refute, like an inflationary state that causes a hot big bang. Everything else? It's nothing but speculation.


Check out some additional information about the (missing) Big Bang singularity. The latest starts with a bang podcast!

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An illustration of our cosmic history, from the Big Bang to the present, in the context of the expanding universe: The hot big bang was preceded by a state of cosmic inflation, but the idea that it must be preceded by a singularity is lamentably outdated. NASA / WMAP Science Team

Almost everyone has heard the story of the Big Bang, but if you ask anyone, from the layman to the cosmologist, to finish the sentence: "In the beginning it was … One of the most common answers is "a singularity," which refers to a moment when all matter and energy in the universe is concentrated on a single point: the temperatures, densities, and energies of the universe would be arbitrary, infinitely large and could even coincide wi The birth of time and space itself.

But this picture is not only wrong, it is almost 40 years old! We are absolutely sure that there was no singularity associated with the hot big bang, and maybe there was not even a birth in space and time. Here's what we know and how we know it.

The GOODS North survey shown here contains some of the most distant galaxies ever seen, many of which are already out of reach. As we look at larger and larger distances, we find that the more distant galaxies seem to be retreating faster and faster due to the expansion of the universe. NASA, ESA, and Z. Levay (STScI) [19659054] When we look at the universe today, we see that it is in all directions at many different distances, full of galaxies. On average, we also find that the farther away a galaxy is, the faster it seems to pull away from us. However, this is not due to the actual movements of the individual galaxies through space. it is due to the fact that the structure of space is expanding.

This was a prediction that was first brought out of the general relativity theory in 1922 by Alexander Friedmann and observingly confirmed by the work of Edwin Hubble and others in the 1920s. It means that matter will spread over time and become less dense as the volume of the universe increases. It also means that as we look into the past, the universe is denser, hotter and more consistent.

Extrapolating all the way back, we come to earlier, hotter and denser states. Does this lead to a singularity in which the laws of physics collapse themselves? NASA / CXC / M.Weiss

If you extrapolate back and forth in time, you would begin to notice some major changes in the universe. In particular:

  • They would come into an era when gravitation did not have enough time to pull matter into enough big piles to have stars and galaxies,
  • They would come to a place where the Universe It was so hot You could not form neutral atoms,
  • and then even atomic nuclei were blasted apart
  • where spontaneous matter-antimatter pairs formed
  • and where individual protons and neutrons would be dissociated into quarks and gluons.

In a singularity, conventional physics collapses, even when talking about the beginning of the universe. However, there are consequences for reaching arbitrarily hot, dense states in the universe, and many of them can not stand observations. © 2007-2016, Max Planck Institute for Gravitational Physics, Potsdam

Each step represents the universe as it was younger, smaller, denser, and hotter. Finally, if you continue, you would see these densities and temperatures rise to infinite values, because all matter and energy in the universe is contained in a single point: a singularity. The hot big bang, as it was first conceived, was not only a hot, dense, expanding state, but a moment when the laws of physics collapsed. It was the birth of space and time: a way to spontaneously bring the entire universe to life. It was the ultimate act of creation: the singularity of the Big Bang.

The stars and galaxies we see today did not always exist, and the farther we go back, the closer an apparent singularity is to the universe of this extrapolation, there is a limit. NASA, ESA, and A. Feild (STScI)

But if this were correct and the universe had reached arbitrarily high temperatures in the past, there would be a number of clear signatures of which we could observe today. There would be temperature fluctuations in the big bang of the Big Bang, which would have enormous amplitudes. The fluctuations we see would be limited by the speed of light; they would only appear on scales of the cosmic horizon and smaller. There would be leftover high-energy cosmic relics from earlier times, like magnetic monopolies.

And yet, the temperature fluctuations are only 1-part-30,000, a thousand times smaller than a single Big Bang predicts. Super Horizon fluctuations are real, both confirmed by WMAP and Planck. And the limitations for magnetic monopolies and other ultra-energy relics are incredibly narrow. These missing signatures have an immense implication: the universe never reached these arbitrarily high temperatures.

The fluctuations in the cosmic microwave background are of such small size and pattern that they strongly suggest that the universe began at the same temperature everywhere and had only 1-part-in-30,000 fluctuations, a fact which is incompatible with an arbitrarily hot big bang. ESA and the Planck Collaboration

Instead, there must have been a cutoff. We can not extrapolate back arbitrarily, 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 validly describe our universe. It was theorized in the early 1980s that before it was hot, dense, expanding, cooling, and full of matter and radiation, our universe ballooned. A phase of cosmic inflation would mean that the universe:

  • is filled with energy inherent in the space
  • which causes a rapid, exponential expansion
  • which expands the universe flatly,
  • gives it the same features everywhere
  • with small amplitude quantum fluctuations,
  • extending to all scales (even over horizontal),

and then inflation comes to an end.

Inflation allows space to expand exponentially, which can quickly cause any pre-existing curved or non-smooth space to appear flat. When the universe is curved, it has a radius of curvature at least a hundred times larger than what we can observe. E. Siegel (L); Ned Wright's Cosmology Tutorial (R)

When it does, it transforms the energy previously inherent in the space itself into matter and radiation, resulting in the Hot Big Bang. But it does not lead to an arbitrarily hot Big Bang, but to a temperature that is at most a hundred times smaller than the magnitude in which a singularity could arise. In other words, it leads to a hot big bang that comes from an inflationary state rather than a singularity.

The information that exists in our observable universe that we can access and measure corresponds only to the last ~ 10 -33 seconds of inflation and everything that came afterwards. If you want to ask how long inflation lasted, we simply have no idea. It took at least a little longer than 10 -33 seconds, but whether it took a little longer, much longer, or for an infinite amount of time is not only unknown, but unknowable.

The cosmic history of the entire known universe shows that we owe the origin of all matter in it and all light ultimately to the end of inflation and the beginning of the hot big bang. Since then, we have had 13.8 billion years of cosmic evolution, a picture confirmed by several sources. ESA and the Planck Collaboration / E. Siegel (corrections)

So what happened to stop inflation? There is a tremendous amount of research and speculation about it, but nobody knows. There is no evidence to point to; no observations we can make; no experiments we can do. Some people (falsely) say something similar to:

Well, we had a big bang singularity that created the hot, dense, expanding universe before we knew about inflation, and inflation is only an intermediate step. That's what it's all about: singularity, inflation and then the hot big bang.

There are even some very famous graphics by top cosmologists that illustrate this picture. But that does not mean that this is right.

Illustration of the variations in density (scalar) and gravitational wave (tensor) resulting from the end of inflation. Note that the assumption that a singularity exists before inflation is not necessarily true. National Science Foundation (NASA, JPL, Keck Foundation, Moore Foundation) – Funded BICEP2 program

There are, in fact, very good reasons to believe that this is not true! In fact, one thing we can demonstrate mathematically is that it is impossible for an inflating state to emerge from a singularity. Here is the reason: Space is expanding exponentially during inflation. Think about how an exponential works: After a while, the universe doubles. Wait twice as long and it will double twice, making it four times as big. Wait three times as long, it doubles three times, making it 8 times larger. And if you wait 10 or 100 times longer, these doublings make the universe 2 times larger 10 or 2 100 .

Which means if we go backwards in time with 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. Accordingly, it would be a half, a quarter, an eighth 2 -10 or 2 -100 times its original size. But no matter how far back you are, you never reach a singularity.

Blue and red lines represent a "traditional" big bang scenario in which everything begins at time t = 0, including space-time itself. In an inflationary scenario (yellow), we never reach a singularity in which the space in transitions to a singular state; instead, in the past, it can only be arbitrarily small while time goes backwards forever. The Hawking-Hartle-No-Boundary condition challenges the longevity of this state, as does the Borde-Guth-Vilenkin theorem, but none of it is certain. E. Siegel

There is a famous theorem among the cosmologists, which shows that an inflationary state is temporally incomplete. What this explicitly means is that if you have any particles in an inflating universe, they will eventually meet if you extrapolate in time. However, this does not mean that there must have been a singularity, but that inflation does not describe everything that happened in the history of the universe, such as its birth. For example, we also know that inflation can not come from a singular state, since an inflation region always has to start from a finite size.

Fluctuations in space-time even on the quantum scale are stretched throughout the universe during inflation over imperfections in both density and gravitational waves. Whether or not inflation originated from a possible singularity is unknown. E. Siegel, with pictures by ESA / Planck and DoE / NASA / NSF's interinstitutional working group on CMB research

Every time you see a diagram, an article or a story about the "Big Bang" Singularity "or any other kind of language seeing big bang / singularity before inflation knows that you are dealing with an outdated mindset. The idea of ​​a Big Bang singularity came out of the window as soon as we realized that we had another state – that of cosmic inflation – that preceded and set up the early, hot, and dense state of the Big Bang. There may have been a singularity at the beginning of space and time, with inflation arising thereafter, but there is no guarantee. There are things in science that we can test, measure, predict and confirm or refute, like an inflationary state that causes a hot big bang. Everything else? It's nothing but speculation.


Check out some additional information about the (missing) Big Bang Singularity, the latest Starts With A Bang Podcast!

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