Skip to comments.Gravitational waves provide dose of reality about extra dimensions (there aren't any)
Posted on 09/15/2018 2:10:37 AM PDT by LibWhacker
In new study, UChicago astronomers find no evidence for extra spatial dimensions to the universe based on gravitational wave data. Credit: Courtesy of NASAs Goddard Space Flight Center CI Lab
While last year's discovery of gravitational waves from colliding neutron stars was earth-shaking, it won't add extra dimensions to our understanding of the universenot literal ones, at least.
University of Chicago astronomers found no evidence for extra spatial dimensions to the universe based on the gravitational wave data. Their research, published in the Journal of Cosmology and Astroparticle Physics, is one of many papers in the wake of the extraordinary announcement last year that LIGO had detected a neutron star collision.
The first-ever detection of gravitational waves in 2015, for which three physicists won the Nobel Prize last year, was the result of two black holes crashing together. Last year, scientists observed two neutron stars collide. The major difference between the two is that astronomers could see the aftermath of the neutron star collision with a conventional telescope, producing two readings that can be compared: one in gravity, and one in electromagnetic (light) waves.
"This is the very first time we've been able to detect sources simultaneously in both gravitational and light waves," said Prof. Daniel Holz. "This provides an entirely new and exciting probe, and we've been learning all sorts of interesting things about the universe."
Einstein's theory of general relativity explains the solar system very well, but as scientists learned more about the universe beyond, big holes in our understanding began to emerge. Two of these are dark matter, one of the basic ingredients of the universe; and dark energy, the mysterious force that's making the universe expand faster over time.
Scientists have proposed all kinds of theories to explain dark matter and dark energy, and "a lot of alternate theories to general relativity start with adding an extra dimension," said graduate student Maya Fishbach, a coauthor on the paper. One theory is that over long distances, gravity would "leak" into the additional dimensions. This would cause gravity to appear weaker, and could account for the inconsistencies.
The one-two punch of gravitational waves and light from the neutron star collision detected last year offered one way for Holz and Fishbach to test this theory. The gravitational waves from the collision reverberated in LIGO the morning of Aug. 17, 2017, followed by detections of gamma-rays, X-rays, radio waves, and optical and infrared light. If gravity were leaking into other dimensions along the way, then the signal they measured in the gravitational wave detectors would have been weaker than expected. But it wasn't.
It appears for now that the universe has the same familiar dimensionsthree in space and one of timeeven on scales of a hundred million light-years.
But this is just the beginning, scientists said. "There are so many theories that until now, we didn't have concrete ways to test," Fishbach said. "This changes how a lot of people can do their astronomy."
"We look forward to seeing what gravitational-wave surprises the universe might have in store for us," Holz said.
I was unaware of any theory that postulates more than three space dimensions. Even the 12 dimensional Heim Extended Quantum Field Theory has only three space dimensions. The rest are time-like.
Just as well. Humans havent figured out how to live properly in the four dimensions we already got.
A press conference has been called for later this coming week at the Baxter Building. Richards is also expected to elaborate on his recent remarks that Annihilus is a graver threat to Earth than climate change.
...Gravitational waves provide dose of reality about extra dimensions (there aren’t any)...
But, what about the other one liberals live in?
This is nine miles over my head, so I’m not pretending to understand it. But I looked it up and, if I got it right, “Bosonic” string theory, which is an early version of string theory, postulated 25 spatial dimensions and one time, and though not in favor, is still being studied.
Wouldn’t this be a blow for string theory and the multiverse?
The major difference between the two is that astronomers could see the aftermath of the neutron star collision with a conventional telescope, producing two readings that can be compared: one in gravity, and one in electromagnetic (light) waves.
“This is the very first time we’ve been able to detect sources simultaneously in both gravitational and light waves,” said Prof. Daniel Holz. “This provides an entirely new and exciting probe, and we’ve been learning all sorts of interesting things about the universe.”
It’s one of the greatest accomplishments of humanity.
Too bad John Wheeler didn’t live long enough to see it.
Yes, you would certainly think so.
Personally, I’m disappointed since I’m a big fan of the multiverse
Here’s a link to the paper:
It says the dimensions considered are non-compact, so perhaps this isn’t a blow for string theory.
I can’t say that since that would imply i understand it, which I don’t. But I can and do say, “DOH!”
We stress that our results do not hold for extradimensional theories with compact extra dimensions (e.g. string theory or the ADD model). The extra dimensions need to be at least on the order of the wavelength of the gravitational waves (∼ 100 km) in orderto have a damping effect. In addition, there may be complications for theories with larger extra dimensions.
Read it, thanks.
Good point about the dimensions. Completely missed it in my reading.
Do you get run-on text in arXiv papers and abstracts, particularly where they change fonts? I get that no matter which device I’m on: PC, Mac, Kindle, smart phone, doesn’t matter.
The multiverse just got wacked.
So does this refute brand theory, or is the relevant scale of the collapsed dimensions all wrong?
Dimensions are not a place where you can go. Dimension means measure. Like “foot” or “mile.”
It displays fine for me at the link I gave.
I downloaded the PDF for the entire paper. It all looks OK.
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