Observational astronomy shows that newly discovered young stellar objects (YSOs) in the immediate vicinity of the supermassive black hole Sagittarius A located in the center of our galaxy behave differently than expected. They describe similar orbits to already known young evolved stars and are arranged in a particular pattern around the supermassive black hole.
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.
Posted in cosmology
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.
Posted in cosmology, information science, mathematics, physics, singularity
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Help translate our videos!
Isaac Newton’s Universal Law of Gravitation tells us that there is a singularity to be found within a black hole, but scientists and mathematicians have found a number of issues with Newton’s equations. They don’t always accurately represent reality. Einstein’s General Theory of Relativity is a more complete theory of gravity. So does using the General Theory of Relativity eliminate the singularity? No. Not only does it concur with Newton’s Universal Law of Gravitation but it also reveals a second singularity, not at the center of the black hole but at the event horizon.
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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.
