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Research led by the University of Amsterdam has demonstrated that elusive radiation coming from black holes can be studied by mimicking it in the lab.

Black holes are the most extreme objects in the universe, packing so much mass into so little space that nothing—not even light—can escape their gravitational pull once it gets close enough.

Understanding black holes is key to unraveling the most fundamental laws governing the cosmos, because they represent the limits of two of the best-tested theories of physics: the theory of general relativity, which describes gravity as resulting from the (large-scale) warping of spacetime by massive objects, and the theory of quantum mechanics, which describes physics at the smallest length scales. To fully describe black holes, we would need to stitch these two theories together and form a theory of quantum gravity.

The IceCube observatory detected 80 of the elusive particles from the heart of spiral galaxy NGC 1,068, also called the Squid Galaxy.

A team of researchers at Universität Heidelberg has built an early universe analog in their laboratory using chilled potassium atoms. In their paper published in the journal Nature, the group describes their simulator and how it might be used. Silke Weinfurtner, with the University of Nottingham, has published a News & Views piece in the same journal issue outlining the work done by the team in Germany.

Understanding what occurred during the first few moments after the Big Bang is difficult due to the lack of evidence left behind. That leaves astrophysicists with nothing but theory to describe what might have happened. To give credence to their theories, scientists have built models that theoretically represent the conditions being described. In this new effort, the researchers used a new approach to build a physical model in their laboratory to simulate conditions just after the Big Bang.

Beginning with the theory that that the Big Bang gave rise to an expanding universe, the researchers sought to create what they describe as a “quantum field simulator.” Since most theories suggest it was likely that the early universe was very cold, near absolute zero, the researchers created an environment that was very cold. They then added potassium atoms to represent the universe they were trying to simulate.

Like Garfield and lasagna.

AT 2020neh is one of a handful of intermediate-mass black holes identified, and the recent “tidal disruption event” saw it feast on a star.

The scientists said their spacetime simulation “agrees very well with theory.”

A team of physicists used a “quantum field simulator” to simulate a tiny expanding universe made out of ultracold atoms, a report from VICE

Simulating spacetime.

Continue reading “Scientists use a quantum state of matter to simulate the early universe’s expansion” »

A tantalizing signal reported by the XENON1T dark matter experiment has sparked theorists to investigate explanations involving new physics.

On June 16, 2020, the collaboration running XENON1T—one of the world’s most sensitive dark matter detectors—reported a signal it couldn’t explain (see today’s accompanying article, Viewpoint: Dark Matter Detector Delivers Enigmatic Signal). The signal has yet to reach the “5-sigma” bar for discovery, and a mundane explanation could still be the culprit. But theorists have been quick to explore whether exotic particles or interactions might be involved. Physical Review Letters followed a special procedure to get a coherent expert review of the proposals it received. Now, the journal is publishing five papers that represent the breadth of theories being pursued.

All of the reported scenarios explain two aspects of the signal, which was produced in the huge vat of ultrapure xenon that makes up XENON1T’s detector. First, the signal looks like it came from particles that collided mostly with the xenon atoms’ electrons. And second, each of these interactions dumped a few keV into the atom.

Something strange has been happening lately. Lots of people are under the impression that images from the James Webb Space Telescope have somehow proven big bang cosmology wrong. This is very stupid and objectively wrong, but it has caused a confusion among even pro-science people, who have been asking me if there is any legitimacy to such claims. I decided a brief debunk was in order, to shine a spotlight on the fraud behind this frenzy, briefly explain why such a claim is so ridiculous, and link to other resources for further information. Enjoy!

Lerner’s dumb article: https://iai.tv/articles/the-big-bang-didnt-happen-auid-2215
Astrophysicist Ethan Siegel explains how Lerner is a crackpot: https://bigthink.com/starts-with-a-bang/has-jwst-disproven-big-bang/
Cosmologist Brian Keating debunks Lerner: https://www.youtube.com/watch?v=iPna7WUODuo.
Astronomer Ned Wright debunks Lerner: https://www.astro.ucla.edu/~wright/lerner_errors.html.
Real scientists use an entire appendix to debunk Lerner’s mistakes: https://iopscience.iop.org/article/10.1086/529134/pdf.

Continue reading “No, The James Webb Space Telescope Did Not Disprove the Big Bang (Eric Lerner is Delusional)” »

An international research team led by the University of Minnesota Twin Cities has measured the size of a star dating back 2 billion years after the Big Bang, or more than 11 billion years ago. Detailed images show the exploding star cooling and could help scientists learn more about the stars and galaxies present in the early universe. The paper is published in Nature.

“This is the first detailed look at a supernova at a much earlier epoch of the universe’s evolution,” said Patrick Kelly, a lead author of the paper and an associate professor in the University of Minnesota School of Physics and Astronomy. “It’s very exciting because we can learn in detail about an individual star when the universe was less than a fifth of its current age, and begin to understand if the stars that existed many billions of years ago are different from the ones nearby.”

The red supergiant in question was about 500 times larger than the sun, and it’s located at redshift three, which is about 60 times farther away than any other supernova observed in this detail.

Quantum chromodynamics (QCD) is one of the pillars of the Standard Model of particle physics. It describes the strong interaction – one of the four fundamental forces of nature. This force holds quarks and gluons – collectively known as partons – together in hadrons such as the proton, and protons and neutrons together in atomic nuclei. Two hallmarks of QCD are chiral symmetry breaking and asymptotic freedom. Chiral symmetry breaking explains how quarks generate the masses of hadrons and therefore the vast majority of visible mass in the universe. Asymptotic freedom states that the strong force between quarks and gluons decreases with increasing energy. The discovery of these two QCD effects garnered two Nobel prizes in physics, in 2008 and 2004, respectively.

High-energy collisions of lead nuclei at the Large Hadron Collider (LHC) explore QCD under the most extreme conditions on Earth. These heavy-ion collisions recreate the quark–gluon plasma (QGP): the hottest and densest fluid ever studied in the laboratory. In contrast to normal nuclear matter, the QGP is a state where quarks and gluons are not confined inside hadrons. It is speculated that the universe was in a QGP state around one millionth of a second after the Big Bang.

The ALICE experiment was designed to study the QGP at LHC energies. It was operated during LHC Runs 1 and 2, and has carried out a broad range of measurements to characterise the QGP and to study several other aspects of the strong interaction. In a recent review, highlights of which are described below, the ALICE collaboration takes stock of its first decade of QCD studies at the LHC. The results from these studies include a suite of observables that reveal a complex evolution of the near-perfect QGP liquid that emerges in high-temperature QCD. ALICE measurements also demonstrate that charm quarks equilibrate extremely quickly within this liquid, and are able to regenerate QGP-melted “charmonium” particle states. ALICE has extensively mapped the QGP opaqueness with high-energy probes, and has directly observed the QCD dead-cone effect in proton–proton collisions. Surprising QGP-like signatures have also been observed in rare proton–proton and proton–lead collisions.