What is the universe like? The question itself doesn’t seem to make much sense..
If, as NASA says, the universe is simply everything, including all space and all the matter and energy it contains, and even time itself, Does everything have a form?
If you are reading this article, you must be one of those who are willing to contemplate the inconceivable, visualize the unimaginable, and spy on the impenetrable.
In other words, to behave like a cosmologist, one of those theorists who try to come up with credible and sustainable ideas about the space that have occupied thinkers for centuries.
For them, the shape of the universe is a serious matter, since it implies the future of the cosmos: depending on what it is, we will know if it will expand forever or reverse its expansion in a cataclysmic Big Crunch, o Great Implosion or Collapse.
Furthermore, knowing the answer to the question at hand gives clues about whether the universe is infinite or finite.
So, How to begin to solve this enigma?
With Albert Einstein.
The idea that space had shape arose with the theory of general relativity of 1915.
And of all the forms that could be considered, this one only allows the universe to take one of three:
- One is that it is curved closed, like a giant sphere in expansion.
- Another is that it be hyperbolic, openly curved, the opposite of a sphere, something like a horse saddle.
- Then there is the flat hypothesis. The cosmos is like A sheet of paperexcept that it has more than two dimensions.
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Einstein left three possibilities.
One of the factors that determine what form it takes is its densitythat is, the amount of matter in a given volume of space.
If it is too large, the force of gravity will exceed the force of expansion, and it will curve into a sphere.
In that case, the universe would be finite, although it would have no end (just as the surface of a ball is not infinite but there is no point on the sphere that can be called “end”).
In addition to being finite, that is the scenario in which the expansion will stop at some point, the galaxies instead of moving away from each other will begin to get closer, until What began with a Big Bang ended with a Great Collapse.
In the other two cases, the hyperbolic and the plane, the universe is infinite and will expand forever.
To establish what it is like (and the future of the cosmos!), solid observational evidence was needed… but of what?
Well, something wonderful.
The oldest light
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The form with the least future.
What cosmologists did was measure cosmic microwave background radiationcold remains of the Big Bang or Great Explosion of about 13.8 billion years ago.
Those traces of when matter, space and time formed, according to the standard cosmological model, are easy to find, says physicist and author Marcus Chown, because they are literally everywhere.
“If you take a cubic centimeter of empty space anywhere in the universe, it contains 300 photons, light particles of this radiation.
“In fact, 99% of all the light in the universe is not that of stars or anything like that, but the glow of the Big Bang“.
It was something that was discovered in 1965, and it is like a photo of the newborn cosmos.
“It is the oldest light and when we capture it with our telescopes, we are looking back as far as we can.
“Encoded in this light is an image of the universe as it was a third of a million years after the Big Bang, a crucial point, as it was when the first structures, the seeds of galaxies, were formed.”
Such radiation remnants are often described as the cosmologist’s Rosetta Stone for deciphering the past, allowing researchers to make detailed deductions from the sparsest observational evidence.
How can so much be inferred from that fossil radiation from the Big Bang?
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The universe could be shaped like a horse saddle.
Doing what some have described as the most difficult measure of science.
That light from the Big Bang that can now be seen in a sphere surrounding the Earth is in the form of very short waves, microwaves, and is a mixture of light and residual heat, extremely weak, although enough to hint at powerful ideas.
It is like “a uniform layer with a nearly constant temperature of about 3 degrees above absolute zero (−273.15 °C),” theoretical astrophysicist Dave Spergel explained to the BBC.
The interesting thing is in the “almost”.
“The small variations are at a level of 100 thousandths of a degree from one place to another.”
That’s what they measured, well “When we look at the microwave background, we learn about the geometry of the universe“said someone who is known for his work with NASA’s WMAP probe, launched in 2001 with the mission of studying the sky and measuring these temperature differences.
It was one of several studies that have helped determine the shape of the universe.
But how can observations of light particles from the Big Bang help astrophysicists like Carlos Frank at Durham University decide what shape it is?
“That’s the beauty of science. We can make very, very momentous inferences based on very detailed data.
“These light particles have been propagating over billions of years until they reach our telescopes, and following any curvature that may be present.”
Depending on how they arrive, you know what their trip was like.
AND?
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The flat universe.
Imagine those cosmic microwaves as two rays of light.
In a flat universe, they will always remain parallel.
In a spherical universe, they will travel along the curvature of space and eventually meet.
In a hyperbolic universe, the rays will never cross and will become increasingly separated.
And it turns out that they remain parallel.
The first time the shape and fate of the cosmos were confidently inferred from observations was in 2000, when an international team of astronomers from Italy, the UK, the US, Canada and France known as the Boomerang collaboration, published the results of their study.
“I think this is the moment that we are going to remember in the textbooks when we said that our universe is flat, we’re not going to end up in a big collapse, we don’t have a limited amount of timewhich will expand forever,” they said.
Those results were later confirmed with data collected by NASA’s WMAP probe, by NASA’s Planck spacecraft. European Space Agency and measurements made with the Atacama Cosmology Telescope.
Evidence of the flatness of the universe also appears in studies of what is known as critical densitywhich indicate that it is just below it, meaning it is flat and will expand indefinitely.
And one more way to find evidence is through the isotropic line: if it is flat, it looks the same from all angles. The Yoresearch found, with a margin of precision of 0.2%, that it did.
Still, we cannot rule out the possibility that we live in a spherical or hyperbolic world..
Although all measures are being taken, there is always the possibility that what happened to us for centuries with the Earth: on the scales that could be observed, its curvature was too tiny to detect, so it was believed to be flat. .
The larger a sphere or saddle is, the flatter each small part of it.
So it remains possible that, since the universe is extremely huge, the part we can observe may be so close to being flat that its curvature can only be detected by super-precise instruments that we have not yet invented.
However, for the moment, Everything seems to indicate that the cosmos is flat, expanding and infinite..
The lovely thing in this world is that often the answers generate more questions… how can it expand if it is infinite? and how can it be infinite if it had a beginning?
We leave it there, lest we be left with nothing to think about.
