Imagine a universe that can turn a spacecraft in one direction and eventually return to its original location. If our universe is a finite donut, such movements are possible and physicists can potentially measure their size.
Thomas Butchart, an astrophysicist at the University of Lyon, the French Center for Astrophysics, told Live Science in an email.
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Examining the light from the very early universe, Bushert and a team of astrophysicists speculated that our universe may be connected in multiples. In other words, space is closed in all three dimensions, like a three-dimensional donut. Such universes are finite, and according to their results, our entire universe may only be about 3-4 times larger than the limits of an observable universe about 45 billion light-years away.
Physicists use the language of Einstein’s general theory of relativity To explain the universe. The language connects the contents of space-time to the bending and distortion of space-time and teaches how it interacts with those contents. This is how we experience gravity. In the context of cosmology, the language connects the contents of the entire universe — Dark matter, Dark energy, ordinary matter, radiation, and everything else — to the overall geometry. For decades, astronomers have been debating the nature of its shape: our universe is “flat” (meaning that imaginary parallel lines remain parallel forever), “closed”. “(Parallel lines finally intersect) or” open “(the lines diverge).
Its geometry in the universe determines its fate. The flat, open universe will continue to expand forever, but the closed universe will eventually collapse on its own.
Multiple observations, especially from the cosmic microwave background (a flash of light emitted only 380,000 years ago in our universe), firmly proved that we live in a flat universe. The parallel lines remain parallel and our universe continues to expand.
But there is more to shape than geometry.There is Topology, This is a way to change the shape while maintaining the same geometric rules.
For example, take a piece of flat paper. It’s clearly flat — parallel lines remain parallel. Then take the two edges of the paper and roll it into a cylinder. Their parallel lines are still parallel: the cylinder is geometrically flat. Then take both ends of the cylindrical paper and connect them. It forms the shape of a donut, and it is also geometrically flat.
Measures of the content and shape of the universe tell us its geometry, which is flat, but not the topology. They do not tell us if our universe is multiple connected. That is, one or more dimensions of our universe are connected to each other.
Look at the light
A completely flat universe Infinity, Flat universes with multiple concatenated topologies have a finite size. If we can somehow determine if one or more dimensions are wrapped in itself, we know that the universe is finite in that dimension. You can then use these observations to measure the total volume of the universe.
But how does the multi-connected universe reveal itself?
A team of astrophysicists at the University of Ulm in Germany and the University of Lyon in France focused on the Cosmic Microwave Background (CMB). Our universe when CMB was released Was one millionth More than today, and if our universe is actually multiple-connected, it was much more likely to envelop itself within the observable limits of the universe at the time. Today, the expansion of the universe makes it much more likely that wrapping will occur on a scale that exceeds observable limits, making wrapping much more difficult to detect. CMB observations give us the best chance to see traces of the multi-connected universe.
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The team paid particular attention to perturbations at CMB temperature (the flashy physics term for bumps and wiggles). If one or more dimensions of our universe reconnect to themselves, the perturbations cannot be greater than the distance around their loops. They simply didn’t fit.
As Buchert explained to Live Science in an email, “In infinite space, there is a perturbation of the temperature of the CMB radiation on all scales, but if the space is finite, wavelengths larger than the size are missing. Of the space. “
In other words, perturbations have a maximum size and may reveal the topology of the universe.
CMB maps created by satellites such as NASA’s WMAP and ESA’s Planck have already seen large and interesting amounts of missing perturbations. Buchert and his collaborators investigated whether these missing perturbations could be attributed to a multi-connected universe. To that end, the team ran a number of computer simulations on what the CMB would look like if the universe were the mathematical name for a three-dimensional donut, and the universe was connected to itself in all three dimensions. ..
“Therefore, we need to run the simulation on a particular topology and compare it to what was observed,” explains Buchert. “Observed CMB variability characteristics indicate” lost force “on a scale that exceeds the size of the universe. The lack of power means that CMB fluctuations are not present on those scales. That means that our universe is multi-connected and finite on its size scale.
“We find that it is in much better agreement with the observed variability than the standard cosmological model, which is considered infinite,” he added.
“You can resize the space and repeat this analysis. The result is the optimal size of the universe that best matches the observations of the CMB. Our paper’s answer is that the finite universe is better than the infinite model. Is also in good agreement with the observations. We can say: now we know the size of the universe. “
The team found that a multi-connected universe, about three to four times the size of an observable bubble, best matches CMB data. This result technically means that you can move in one direction and return to where you started, but you can’t really achieve that.We are alive In the expanding universeAnd, on a large scale, the universe is expanding faster than the speed of light, so you could never catch up and complete the loop.
Buchert emphasized that the results are still preliminary. The effects of the equipment can also explain the lack of large fluctuations.
Still, it’s fun to imagine living on the surface of a giant donut.
Originally published in Live Science.
Our universe may be a really huge three-dimensional donut.
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