But there may be an opportunity to discover traces of those gravitons indirectly.
One of the strategies Vafa and his collaborators are pursuing is based on large-scale cosmological surveys that chart the distribution of galaxies and matter. There may be “small differences in clustering behavior” in these distributions, Obeid said, which could indicate the presence of dark gravitons.
When a heavier dark graviton collapses, it produces a pair of lighter dark gravitons with a total mass slightly less than the mass of the parent particle. The lost mass is converted into kinetic energy (according to Einstein’s formula, E = Mac2), giving the newly created graviton a small boost, giving it a “kick speed” estimated at about 1/10,000 times the speed of light.
These kick speeds can influence how galaxies form. According to the standard cosmological model, galaxies begin as clumps of matter whose gravity pulls more matter together. However, a graviton with sufficient kick speed can escape from this gravitational grip. If this were to happen, the resulting galaxy’s mass would be slightly less than standard cosmological models predict. Astronomers can look for this difference.
Recent observations of cosmic structure from the Kilodegree survey are so far consistent with the dark dimension: analysis of data from that survey set an upper limit The kick velocity was very close to what Obied and his coauthors predicted. The Euclid Space Telescope, launched last July, will undergo more rigorous testing.
Meanwhile, physicists also plan to test the idea of a dark dimension in the laboratory. If gravity leaks into a dark dimension one micron in diameter, in principle he could look for deviations from the expected gravity between two objects the same distance apart.It’s not an easy experiment to carry out. Armin Shaegui, a physicist from the Austrian Academy of Sciences who is conducting the tests. But, he added, “there’s a simple reason why we have to do this experiment.” “Until you see it, you won’t know how gravity works at such close distances.”
of Closest measurement to dateIn an experiment conducted at the University of Washington in 2020, the distance between the two specimens was 52 microns. The Austrian group hopes to eventually reach the 1-micron range, which is predicted to be the dark dimension.
While physicists are intrigued by the dark dimension proposal, others are skeptical that it will work. “It would be very interesting to look for extra dimensions through more precise experiments,” he said. Juan Maldacena“But I think the probability of discovering them is low,” said a physicist at the Institute for Advanced Study.
joseph conlonThe Oxford University physicist shares that skepticism. This is one of his. I think the speculation on which it is based is somewhat ambitious, and the current evidence is quite weak. ”
Of course, the weight of evidence can change, which is why we conduct experiments in the first place. The dark dimension proposal, if supported by future experiments, could explain what dark matter is, how it is related to both dark energy and gravity, and why gravity is different from other known forces. We may be able to get closer to understanding why it seems weak in comparison. “Theorists are always trying to make this ‘connection’. The dark dimension is one of the most promising ideas I’ve heard in this direction,” Gopakumar said.
But ironically, one thing the dark dimension hypothesis cannot explain is why the cosmological constant is so surprisingly small. This puzzling fact essentially started this line of research. “It’s true that the show doesn’t explain that fact,” Vafa acknowledged. “But what this scenario tells us is that when lambda is small, and we spell out the consequences, a series of surprising things can go right.”
original story Reprinted with permission from Quanta Magazine, Editorially independent publication simmons foundation Its mission is to enhance the public’s understanding of science by covering research developments and trends in mathematics, physical sciences, and life sciences.
