Posted on 11/05/2023 7:14:40 AM PST by SunkenCiv
In this week's science news, I talk about a new candidate for a cosmic string, the mysterious shrinking of planet Mercury, a nuclear clock, the first quantum engine, a simulator for human diseases, whether we can find new physics with spinning black holes, AI that wants to help find aliens, how to compute with photons, and of course, the telephone will ring.
Could this be the first evidence for string theory? | 18:21
Sabine Hossenfelder | 1.03M subscribers | 310,893 views | October 10, 2023
(Excerpt) Read more at youtube.com ...
Transcript · Intro 0:05 · Welcome everyone to this week's science news. Today we'll talk 0:09 · about a new candidate for a cosmic string, the mysterious shrinking of planet Mercury, 0:15 · a nuclear clock, the first quantum engine, a simulator for human diseases, 0:21 · whether we can find new physics with spinning black holes, AI that wants to help find aliens, 0:27 · how to compute with photons, and of course, the telephone will ring. · A new candidate for a cosmic string 0:33 · Astronomers might have found evidence for a cosmic string. 0:36 · A cosmic string is a hypothetical giant thread of pure energy, longer than a galaxy and with 0:43 · basically zero thickness. The existence of cosmic strings was first proposed in the 1970s, 0:49 · as leftover topological defects from the plasma in the early universe. 0:55 · However, that idea was ruled out because it didn't fit with the properties of the cosmic microwave 1:00 · background that were observed in the 1990s. The idea of cosmic strings was then revived 1:07 · by string theorists who argued that under certain circumstances, the normally tiny strings of string 1:14 · theory could grow to such huge proportions. Because of its high energy density, a cosmic 1:20 · string would act as a strong gravitational lens, and because it's a one-dimensional object, 1:26 · it would very cleanly duplicate images behind it. Basically, one image goes left 1:32 · around the string, the other one right. So if you're looking for cosmic strings, 1:36 · you look for galaxies that seem to appear twice and there's no visible cause of lensing. 1:43 · In the new paper, the astronomers report that they've identified several cosmic 1:48 · string candidates in data that was collected by the Planck satellite and that they followed 1:54 · up on with further observations at the Himalayan Chandra Telescope. This way, 1:59 · they identified one candidate in particular that seems to be an almost perfect duplication 2:06 · and that could have been created by a cosmic string. They did a spectral analysis of both 2:11 · parts of the image and found that the spectra look almost identical. In case that sounds convincing, 2:18 · let me add that the spectrum mostly tells you what the galaxy is made 2:21 · up of, and nearby galaxies are quite plausibly made of similar star stuff. 2:27 · We had a candidate for a cosmic string already in 2006 when the Hubble telescope spotted a 2:33 · similar double dot. It turned out to be a pair of galaxies. So don't get too excited, 2:39 · it might just be one damn string after another. Planet Mercury is shrinking. Geologists have · The mysterious shrinking of planet Mercury 2:47 · known for some time that it has been shrinking in the past. New is 2:52 · that they've found it's still shrinking . Mercury seems to be undergoing a process 2:57 · known as "global contraction". It's becoming wrinkly, basically, 3:02 · kind of like an old apple. Scientists estimate that it's lost a few kilometres in diameter in 3:08 · the past few billion years. They first suspected this in the 1970s when the Mariner 10 mission 3:14 · sent images back to Earth, and the surface of Mercury looked very wrinkly. They got 3:20 · better data in 2015 from the Messenger mission which confirmed the suspicion. 3:25 · Just exactly why Mercury shrinks is somewhat unclear. It could be that it's cooling at a 3:31 · rapid rate or it could be that it's to do with the slowing down of its spin, 3:36 · and there are some more ideas floating around in the literature. 3:40 · In the new paper now they analysed the data from the messenger mission in detail. Mercury 3:45 · is covered in grabens, which are downward dips. Grabens have an upward counterpart, 3:51 · called horsts. The geologists say that these grabens must be "relatively young" by which 3:57 · they mean less than 300 million years. They think so because otherwise these 4:02 · grabens would have been covered up by sediments and rubble. So, they conclude, 4:07 · Mercury hasn't stopped shrinking. ESA is about to send a spacecraft to Mercury in 4:12 · 2025, which will hopefully tell us more about what's going on there. 4:16 · So it's not just us who are becoming more and more wrinkly, Mercury shares our fate. Though I'm very 4:23 · pleased that at less than 300 million years I can still be considered "relatively young". · A nuclear clock 4:30 · Researchers from Germany and the United States have found a way to build a clock 4:35 · that keeps time with a record accuracy of one second in three hundred billion years, 4:42 · and they did it with a big X-ray laser. Atomic clocks are currently the most precise way 4:47 · of keeping time. They work by tuning a laser to a resonance frequency between atomic energy levels. 4:54 · At the moment, the most widely used resonance on is in Caesium atoms. The accuracy of these Caesium 5:01 · clocks is roughly one second in three hundred million years. These clocks are so precise because 5:08 · the resonance is an incredibly reliable pacemaker, determined solely by the properties of the atom. 5:15 · Now, some atoms have more, others less suitable resonances, 5:20 · but the typical frequency of these resonances is determined by the mass of the electron, 5:25 · so there are no big gains to be made by switching to other atoms. 5:30 · However, instead of using a resonance between electron levels, you can use a resonance of 5:36 · the atomic nucleus. This is an advantage because nuclear resonances are at much higher energies. 5:43 · Higher energies mean smaller wavelengths, and therefore higher precision for the pace-maker. 5:49 · Nuclei are also less susceptible to environmental disturbances, so they make more accurate clocks. 5:55 · One of the nuclei that scientists have looked at is scandium which has atomic number 21. 6:02 · This is because the structure of its nucleus gives it an incredibly narrow resonance that 6:07 · would make for a very accurate pace maker. But if you want to use that as a clock, 6:13 · first thing you need to do is to measure the resonance. This is what the new study is about. 6:18 · In the paper that was just published in the journal Nature, the researchers report that 6:24 · they were able to measure the resonance in scandium nuclei with unprecedented precision. 6:30 · It would allow timekeeping with an accuracy one thousand times better than current atomic clocks, 6:37 · roughly one second in three hundred billion years, or about three femtoseconds per second. 6:44 · The difficulty in using resonances of nuclei instead of atomic energy levels is that they 6:49 · are at much higher energies, which means you need to excite them with lasers of higher 6:54 · frequencies. This is what they need the X-ray laser for. Scandium is not the only nuclei you 7:01 · can use to build a nuclear clock. There is also a European group working on building a 7:06 · nuclear clock based on a Thorium resonance. They're not just doing this because they 7:11 · like playing with X-ray lasers. Timekeeping accuracy is relevant in many research areas, 7:17 · notably navigation and space travel. Your tax office would also really like to be 7:22 · able to fine you for handing in your tax return 3 femtoseconds too late. · The first quantum engine 7:28 · Scientists in Japan and Germany have worked together to build the first quantum engine. 7:34 · This engine exploits the difference between bosons and fermions, that are different types 7:40 · of particles. Fermions don't like to share the same space. Bosons on the other hand, 7:45 · find it cozy to sit in the same place. Electrons are fermions, and that they don't like to share 7:52 · space is why we have atomic energy shells, otherwise electrons would just all sit on the 7:58 · same shell. But it's not just elementary particles which are bosons or fermions, 8:03 · entire atoms have similar properties, depending on how their electron shells are filled. 8:08 · These two groups of particles are not as distinct as you may think because you can 8:14 · combine two fermions to a boson. And that's what they did in the new paper. 8:19 · They used an ultracold gas of about 60 000 Lithium atoms which at the beginning 8:25 · were fermions and sat very spaced out. Then they applied a magnetic field that 8:31 · coaxed the fermions to combine to bosons and they moved closer together. Finally 8:37 · they relaxed the field and the atoms become fermions again. So they've converted the 8:43 · energy from the magnetic field to mechanical energy. It's an engine. 8:48 · This is indeed very similar to how car engines work, if you think about it. You inject petrol, 8:53 · ignite it, it expands and pushes a piston which drives a motor. In the quantum engine, 9:00 · the expansion comes from the transition from bosons to fermions. 9:04 · This quantum engine isn't going to move a car any time soon because it works at temperatures 9:09 · near absolute zero, but it's another step on the way to putting "quantum" before every other word. · A simulator for human diseases 9:17 · A new device about the size of a lunchbox can tell scientists how 9:21 · the human body would react to various drugs and diseases. The device is called Lattice, 9:27 · and it was built by scientists at Northwestern University in the US. 9:32 · They envision it as an alternative to conventional in vitro technologies. 9:37 · The device consists of eight wells, which can contain anything from organ tissue to bacteria. 9:43 · The wells are interconnected by a series of pumps and channels that transport artificial 9:48 · blood or other liquids. This allows researchers to simulate interactions between tissue in various 9:54 · parts of the body, which is difficult to do with current in vitro technologies. They have already 10:00 · begun using it to study the origin of polycystic ovarian syndrome. Over time, the researchers hope, 10:07 · the device could become popular in laboratories that study physiology and pathology. 10:13 · Next time you make jokes about physicists because they describe humans as approximately spherical, 10:19 · keep in mind that for doctors you're basically a box with pumps and channels. · Can we find new physics with spinning black holes 10:25 · I got a lot of questions about these headlines which say that spinning black holes can help us 10:31 · find new physics. They're about something called a Kerr black hole, or so the news seems to say. 10:38 · What's a Kerr black hole? A Kerr black hole is just a spinning black hole. It's named after the 10:43 · New Zealand physicist Roy Kerr who was first to write down the maths for it. Black holes almost 10:50 · always rotate, just because it's incredibly unlikely that matter which collapses to a 10:55 · black hole had no initial angular momentum, and the angular momentum must be conserved. 11:01 · So if one could use spinning black holes to find new physics that'd be pretty cool. 11:07 · But if you look at the news somewhat closer, or even better have a look at the paper, 11:12 · you'll see that it's not about just Kerr black holes, but extremal Kerr black holes. 11:18 · That they're extremal doesn't mean they like sky diving, it means that they rotate at the maximal 11:24 · speed that's theoretically possible. Extremal black holes don't exist in the real universe. 11:30 · The authors of the paper estimate what quantum effects one should expect for gravity to appear 11:36 · near such extremal black holes, or black holes that are near extremal. They find that those 11:42 · effects would become very noticeable and would probably be measurable if those things existed. 11:48 · --What they say is almost certainly correct, though I admit that I didn't check the maths. 11:53 · If I want to worry about stuff that doesn't exist, I can just think about my pension savings. 12:01 · Hello? 12:02 · Ah, hi Elon, 12:06 · No more headlines with the images? Yes, 12:12 · great idea, better not confuse people with too much information. 12:17 · Ah, it's much easier to comment on an article if you don't know 12:22 · what it's about. It'll be great! Love you too! 12:26 · By the way this video comes with a quiz on quizwithit dot com. 12:32 · Even better! If you subscribe to quizwithit, you can collect points from all our videos, 12:37 · and you get free access to the transcripts with links to all references. 12:42 · It's an easy way to support both our channel and, hopefully, your memory, 12:47 · so go and check it out. · AI that wants to help find aliens 12:49 · Artificial intelligence is already helping us with a bewildering variety of tasks, from 12:55 · locating hard-to-find tumours to conducting beach cleanup missions. But it's got a new mission: 13:01 · To help find life on other planets. That's right, AI is joining the search for aliens. 13:07 · In a recent paper, researchers in the United States say AI can help 13:12 · differentiate biological traces from non-biological samples. They trained 13:16 · their algorithm on more than one hundred and thirty samples which human scientists 13:22 · had already labelled to be of biological or non-biological origin. After that training, 13:27 · the program was able to judge other samples with 90 percent accuracy, correctly identifying 13:34 · recent biological traces that had come for example from shells, teeth, or rice, 13:39 · but also ancient ones such as coal, oil, or amber. Identifying the biological origin of old samples 13:45 · is no small feat, because organic molecules tend to degrade over time. The researchers believe 13:52 · their program could help nail down the origin of ancient sediments, for example those on Mars. 13:58 · So far they're only proposing to use AI to look for alien life in sediments, 14:04 · so don't worry, your little secret is safe a little longer. · How to compute with photons 14:09 · Scientists in China have found a way to simplify a method used in photonic 14:13 · computing, saving both space and energy. Photonic computing works by shooting laser 14:20 · light through microscopic optical components. Depending on how the light is routed with 14:25 · mirrors and beam splitters, it can execute different calculations. You then read out 14:31 · the result when the light exits the setup, or return it for the next step of the calculation. 14:37 · Photonic computing is especially useful for matrix multiplication, 14:42 · where the matrices are represented by a grid of tiny interferometers. These 14:47 · photonic components are a very direct encoding of the matrix multiplication. 14:52 · This is very energy and time efficient because in normal computers you don't encode matrices 14:58 · directly in hardware, but indirectly in bits that stand for certain matrix elements, 15:04 · and transistors that operate on them. This might sound rather boring, but matrix multiplications 15:10 · are a common element of many real-world operations, from population studies, 15:15 · to economics and finance, to biology. However, if you directly encode a 15:20 · matrix in a photonic computer, then this'll generally be a complex valued matrix, that is, 15:27 · a matrix whose entries are complex numbers. This is because photons in an interferometer 15:33 · carry two types of information: which path they go, and how they interfere, that is, their phase. 15:39 · Using photons for calculating with complex valued matrices has been done before. But for 15:45 · most everyday applications, one doesn't need complex numbers—real numbers will 15:50 · do. So using an approach that encodes complex numbers is somewhat wasteful. 15:55 · In the new paper now, the researchers have found a way to simplify photonic matrix 16:00 · multiplication so that it works more efficiently for real numbers. They did this smartly removing 16:08 · some components which reduced the size of the chips and also made them more energy efficient. 16:14 · This development is part of a general trend we're seeing in computing, 16:19 · that certain types of calculations are being run on specialized hardware to speed them up. This 16:25 · is also the motivation behind quantum simulations and neuromorphic computing, it's the computerized 16:32 · version of outsourcing to specialists basically. When they said that photonic computing is 16:38 · getting real, they might not have meant what you thought they meant. · Learn Science with Brilliant 16:43 · I hope we can all agree that science news is great, but it's really just the icing on 16:48 · the cake. The big cake is all the fascinating ways that nature works. A free and easy way to 16:54 · learn more about the big cake of science is to have a look at Brilliant dot org. 16:59 · Brilliant is a fresh and new approach to learning. They offers courses on a large variety of topics 17:05 · in science and mathematics. All their courses come with interactive visualizations and follow up 17:11 · questions. Some also have videos for demonstration experiments or executable python scripts. This 17:18 · really gives you a feeling for what is going on. Whether you want to know more about solar panels, 17:24 · neural networks, astrophysics, special relativity, or computational biology, 17:30 · Brilliant has you covered. And they're adding new content each month. 17:35 · I even have my own course on Brilliant that's an introduction to quantum mechanics. It's 17:40 · a beginner's course and covers topics such as interference, superpositions and entanglement, 17:47 · the uncertainty principle, and Bell's theorem. And after that you can continue learning more about 17:54 · quantum objects or maybe quantum computing. To give it a try yourself, use our link 18:00 · Brilliant dot org slash Sabine and sign up for free. You'll get access to everything Brilliant 18:06 · has to offer for 30 days, and the first 200 subscribers using this link will get 18:11 · 20 percent off the annual premium subscription. Thanks for watching, see you next week.
Whut?
No.
But it is entertaining. Thanks for the transcript.
Speak of Ai if anyone is interested, here is a free Ai for text, no sign up, no pay.
https://magicwrite.netlify.app/?ref=theresanaiforthat
I don’t know how good it is though, I asked it if Hillary Clinton is truly the daughter of Satan and it gave me this obviously biased answer:
“No, there is no factual evidence or credible information to support the claim that Hillary Clinton is the daughter of Satan. Conspiracy theories and false accusations have circulated about various individuals throughout history for various reasons, but it is important to approach such claims critically and rely on verified sources of information.”
The Devil you say?
Theoretical physicists will tell you that for the most part advancements in polishing the standard model are stuck. There has been many efforts to find the unified field theory etc. None have held up to scrutiny. This too shall pass away.
Love Doctor Professor Hossenfelder.
Cute little voice, some parody, often expresses her own amazement about something she probably should have known (and probably already did know) about. The recent vids are in the link, lots of variety that should make some more topics in the near future.
Various string theories that postulate extra dimensions attempt to explain the forces and fields that physics discerns in a unified way, but, as you point out, no string theory has yet passed scrutiny. We seem to be in an impasse similar to the crisis of classical physics in the late 19th and early 20th century.
My guess is that the answer will come from someone on the margins like Einstein once was, a physics doctoral student whose dissertation had been rejected, earning an income as a Swiss patent reviewer while he wrote four extraordinary papers that revolutionized physics.
Quantum theory is 100 years old.
True. And, as has been said, if you think that you understand quantum theory, you don’t. Most notably, quantum entanglement is both well-established and utterly contrary to common sense. Einstein disliked quantum entanglement so much that he referred to it disparagingly as “spooky action at a distance.”
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