Physicists haven’t yet ruled out the possibility that the universe has a complicated topology in which space loops back around on itself.
Category: physics – Page 81
Neutron-rich nuclei reveal how heavy elements form
Models for how heavy elements are produced within stars have become more accurate thanks to measurements by RIKEN nuclear physicists of the probabilities that 20 neutron-rich nuclei will shed neutrons.
Stars generate energy by fusing the nuclei of light elements—first hydrogen nuclei and then progressively heavier nuclei, as the hydrogen and other lighter elements are sequentially consumed. But this process can only produce the first 26 elements up to iron.
Another process, known as rapid neutron capture, is thought to produce nuclei that are heavier than iron. As its name suggests, this process involves nuclei becoming larger by rapidly snatching up stray neutrons. It requires extremely high densities of neutrons and is thus thought to occur mainly during events such as mergers of neutron stars and supernova explosions.
A Groundbreaking Scientific Discovery Just Created the Instruction Manual for Light-Speed Travel
In a first for warp drives, this research actually obeys the laws of physics.
Physicists create five-lane superhighway for electrons
MIT physicists and colleagues have created a five-lane superhighway for electrons that could allow ultra-efficient electronics and more. The work, reported in the May 9 issue of Science, is one of several important discoveries by the same team over the last year involving a material that is essentially a unique form of pencil lead.
AI and Physics Combine to Reveal the 3D Structure of a Flare Erupting around a Black Hole
Scientists believe the environment immediately surrounding a black hole is tumultuous, featuring hot magnetized gas that spirals in a disk at tremendous speeds and temperatures. Astronomical observations show that within such a disk, mysterious flares occur up to several times a day, temporarily brightening and then fading away.
Now a team led by Caltech scientists has used telescope data and an artificial intelligence (AI) computer-vision technique to recover the first three-dimensional video showing what such flares could look like around SagittariusA* (Sgr A• the supermassive black hole at the heart of our own Milky Way galaxy.
The 3D flare structure features two bright, compact features located about 75 million kilometers (or half the distance between Earth and the sun) from the center of the black hole. It is based on data collected by the Atacama Large Millimeter Array (ALMA) in Chile over a period of 100 minutes directly after an eruption seen in Xray data on April 11, 2017.
I Fear Maladaptive Culture
From the article by Robin Hanson, a professor of economics who also holds degrees in physics and computer science.
So this remains my worry: our rapid rates of change in unconditional choices of cultural norms are not mostly driven by reason, but instead by a cultural evolution process that has…
I’ve been reading, thinking, and talking, trying to get clearer on what exactly are the culture problems I’m worried about, and how best to describe them. I seek descriptions not only easy for an outsider public to understand, but also for prestigious insider specialists to embrace.
It seems maladaptive culture might be a better name for the problem. So that is the title of this post. Also, I tentatively see four key ways to distinguish more from less problematic cases; the big problems that I fear sit mainly in one corner of that 16-cornered 4D cube of possibilities. Here are the four dimensions:
1. First, culture can work great when tied to particular relevant observable outcomes and inputs. If you want to catch more fish, it can make sense to copy the fishing-related behaviors of the people around you who catch the most fish. You need to be able to tell who gets more fish value (e.g., quantity and size) per effort invested (e.g., time and harms) and you also need to be able to tell which of these folks’ many features and behaviors are plausibly oriented to catching fish. So you can’t do this sort of cultural change until you’ve developed sufficient cultural gadgets to see these things. But once you do, things can work great.
Hidden citations in physics may obscure true impact
In the scientific literature, a citation acts as a mechanism to signal prior knowledge, enhance credibility, and protect against plagiarism. But it also gives credit to the individual or team who established or discovered the knowledge in question, and citations have thus emerged as a metric to measure the impact of a work or researcher.
How do we know how much dark matter there is in the Universe?
AD — Go to https://ground.news/drbecky to stay fully informed with the latest Space and Science news. Subscribe through my link to get 40% off the Vantage plan for unlimited access this month only. | I often get asked how do we know dark matter exists? Which is why I’ve made a video on all the observational evidence we have before (linked below)! But occasionally I’ll get asked how do we know how much dark matter there is, which is a really fun question. There’s many different ways we can calculate this, including the ratio between normal (baryonic) and dark matter, but in this video I just wanted to highlight three different ways astrophysicists calculate this.
Here’s my previous video on all the evidence we have for dark matter — • All the evidence we have for dark mat…
My previous video on whether dark matter could be made of black holes — • Is dark matter made of black holes?
My previous video on whether black holes contain dark matter — • Do black holes contain dark matter?
My previous video on why galaxies merge if the universe is expanding — • If the Universe is expanding, then wh…
Allen, Evrard \& Mantz (2011; review on galaxy clusters observations) — https://arxiv.org/pdf/1103.4829
Zwicky (1933; first virial theorem paper in German) — https://articles.adsabs.harvard.edu/p…
Zwicky (1937; virial theorem applied to the Coma cluster) — https://articles.adsabs.harvard.edu/p…
Alpher, Bethe, \& Gamow (1948; big bang nucleosynthesis; behind paywall) — https://journals.aps.org/pr/abstract/.…
Alpher \& Herman (1950; more BBN work; behind paywall) — https://journals.aps.org/rmp/abstract…
Planck collaboration (2015; cosmological parameter results for our best model of the Universe) — https://arxiv.org/pdf/1502.
00:00 Introduction.
02:04 Ground News AD
03:54 Method 1 — Galaxy Clusters and the virial theorem.
08:49 Method 2 — Big Bang Nucleosynthesis.
11:39 Method 3 — Cosmic Microwave Background.
14:35 Outro.
15:24 Bloopers.
Video filmed on a Sony ⍺7 IV
🎧 Royal Astronomical Society Podcast that I co-host: podfollow.com/supermassive.