Are points of infinite curvature, where general relativity breaks down, always hidden inside black holes? An audacious attempt to find out is shedding light on the mystery of quantum gravity.
The study is based on several intriguing coincidences. First, observations show that there is about the same amount of ordinary and dark matter, which exceeds baryonic by about five times. And secondly, neutrons and protons have almost the same mass, which allows them to form stable atoms — this is a random but stable property of the quantum world, because otherwise our universe would not be home to any of the atoms that make up stars, planets and ourselves.
In fact, the theory suggests that there may be a parallel universe like ours in which neutrons and protons do not have such convenient symmetry in mass. In this world, there is a “soup” of subatomic particles that interact little, which explains why dark matter does not seem to clump together.
It is important to note that this is just one more of many hypotheses that try to explain the mystery of dark matter – an annoying and lingering unknown in our understanding of the universe.
Quantum field theory techniques are employed to compute the conservative scattering dynamics of a pair of black holes to the fifth order in Newton’s constant.
Scientists may be one step closer to unraveling one of the universe’s greatest mysteries. Their recent calculations suggest that neutron stars could play a crucial role in shedding light on the mysterious dark matter.
In a paper published in The Journal of Cosmology and Astroparticle Physics, physicists from the ARC Centre of Excellence for Dark Matter Particle Physics, led by the University of Melbourne, calculated that energy transferred when dark matter particles collide and annihilate inside cold dead neutron stars can heat the stars up very quickly.
It was previously thought that this energy transfer could take a very long time, in some cases, longer than the age of the universe itself, rendering this heating irrelevant.
This is the question of the origin of our Universe. Every star, every galaxy and every planet we see came from the Big Bang. But what was before it?
Is dark matter primordial black holes? If so, could we find them using Apollo-era technology on the moon?
A new paper suggests the answer may be yes to both. I interviewed David Kaiser, one of the paper’s co-authors, former student of inflationary cosmology pioneer Alan Guth, and now Professor of Physics and Professor of the History of Science at MIT.
For the preprint of the full paper:
https://arxiv.org/pdf/2310.16877
and other press about the paper.
https://www.lrb.co.uk/the-paper/v46/n…
https://news.mit.edu/2024/exotic-blac…
And some other related papers:
https://journals.aps.org/prl/abstract…
https://arxiv.org/abs/2303.02168
https://arxiv.org/abs/2312.17217
a timeline is below.
00:00 introduction.
00:57 primordial black holes.
3:05 particle dark matter and modified gravity.
6:33 LIGO and EHT
11:03 window of opportunity.
15:16 observaitonal signatures.
20:30 Apollo era tech.
25:19 Star Wars.
25:54 the future.
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Be sure to check out the Infinite Series episode Singularities Explained • Singularities Explained | Infinite Se… or How I Learned to Stop Worrying and Divide by Zero.
It’s still just a plan, but a new telescope could soon be measuring gravitational waves. Gravitational waves are something like the sound waves of the universe. They are created, for example, when black holes or neutron stars collide.
The future gravitational wave detector, the Einstein Telescope, will use the latest laser technology to better understand these waves and, thus, our universe. One possible location for the construction of this telescope is the border triangle of Germany, Belgium and the Netherlands.
Black holes and neutron stars are among the densest known objects in the universe. Within and around these extreme astrophysical environments exist plasmas, the fourth fundamental state of matter alongside solids, liquids, and gases. Specifically, the plasmas at these extreme conditions are known as relativistic electron-positron pair plasmas because they comprise a collection of electrons and positrons—all flying around at nearly the speed of light.
While such plasmas are ubiquitous in deep space conditions, producing them in a laboratory setting has proved challenging.
Now, for the first time, an international team of scientists, including researchers from the University of Rochester’s Laboratory for Laser Energetics (LLE), has experimentally generated high-density relativistic electron-positron pair–plasma beams by producing two to three orders of magnitude more pairs than previously reported. The team’s findings appear in Nature Communications.
What is gravity without mass? Both Newton’s revolutionary laws describing its universal effect and Einstein’s proposal of a dimpled spacetime, we’ve thought of gravity as exclusively within the domain of matter.
Now a wild new study suggesting that gravity can exist without mass, conveniently eliminating the need for one of the most elusive substances in our Universe: dark matter.
Dark matter is a hypothetical, invisible mass thought to make up 85 percent of the Universe’s total bulk. Originally devised to account for galaxies holding together under high speed rotation, it has yet to be directly observed, leading physicists to propose all sorts of out-there ideas to avoid invoking this elusive material as a way to plug the holes in current theories.
