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Category: cosmology – Page 278

Let me back up a moment. I recently concurred with megapundit Steven Pinker that over the last two centuries we have achieved material, moral and intellectual progress, which should give us hope that we can achieve still more. I expected, and have gotten, pushback. Pessimists argue that our progress will prove to be ephemeral; that we will inevitably succumb to our own nastiness and stupidity and destroy ourselves.

Maybe, maybe not. Just for the sake of argument, let’s say that within the next century or two we solve our biggest problems, including tyranny, injustice, poverty, pandemics, climate change and war. Let’s say we create a world in which we can do pretty much anything we choose. Many will pursue pleasure, finding ever more exciting ways to enjoy themselves. Others may seek spiritual enlightenment or devote themselves to artistic expression.

No matter what our descendants choose to do, some will surely keep investigating the universe and everything in it, including us. How long can the quest for knowledge continue? Not long, I argued 25 years ago this month in The End of Science, which contends that particle physics, cosmology, neuroscience and other fields are bumping into fundamental limits. I still think I’m right, but I could be wrong. Below I describe the views of three physicists—Freeman Dyson, Roger Penrose and David Deutsch—who hold that knowledge seeking can continue for a long, long time, and possibly forever, even in the face of the heat death of the universe.

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Because leviathan black holes would never fit in a lab, Jeff Steinhauer and his research team created a mini one right here on Earth.

When something rips physics apart, you cross over into the quantum realm, a place inhabited by black holes, wormholes and other things that have been the stars of multiple sci-fi movies. What lives in the quantum realm either hasn’t been proven to exist (yet) or behaves strangely if it does exist.

Black holes often venture into that realm. With these collapsed stars — at least most of them are — being impossible to fly a spacecraft into (unless you never want to see it again), one physicist decided that the best way to get up close to them was under a literal microscope. Jeff Steinhauer wanted to know whether black holes radiate particles like the late Stephen Hawking theorized they would. Because one of these leviathans would never fit in a lab, he and his research team created one right here on Earth.

“We have to understand how we see the Hawking radiation sound waves falling in and coming out,” Steinhauer, who co-authored a study recently published in Nature Physics, told SYFY WIRE. “They should be very slight. Seeing this radiation from a real black hole is too weak and would be totally overpowered by other sources of radiation, which is why we want to see it in an analog system.”

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Blackholes are a breakdown in the equations of spacetime. This means both space and time no longer behave the way we would expect of them.
Today we explore the breakdown in time around blackholes and what it means to interact with the event horizon, or the place where time appears to stand still.

Further Reading/Consumption:

Black holes & time warps: einstein’s outrageous legacy — kip thorne.

Your Daily Equation #31: BLACK HOLES: And Why Time Slows Down When You Are Near One — https://youtu.be/qph51qUgwgU

What happens to you if you fall into a black hole? — https://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/fall_in.html.

Physics Beyond the Event Horizon — https://knotphysics.net/black-holes

Continue reading “Why Time “Stops” in a Black Hole” | >

Go to https://NordVPN.com/sabine to get a 2-year plan plus 4 additional months with a huge discount!

At 2 mins 26 seconds when I say “Peter” I meant “Paul”. Sorry!

Dark energy has got something to do with quantum vacuum fluctuation, whoa, physics. You have probably heard something like that. Alas, that isn’t quite right. In this video I clear up the confusion. Vacuum energy is much easier to understand than you might have been told. And it doesn’t fluctuate.

You can support us on Patreon: https://www.patreon.com/Sabine.

0:00 Intro.
0:27 Vacuum Energy according to Scientific American.
2:07 Vacuum Energy according to Sabine.
7:11 The Gas Analogy for Dark Energy.
10:04 Sponsor Message.

#physics #science

Continue reading “Physicist Despairs over Vacuum Energy” | >

Deep Learning systems can achieve remarkable, even super-human performance through supervised learning on large, labeled datasets. However, there are two problems: First, collecting ever more labeled data is expensive in both time and money. Second, these deep neural networks will be high performers on their task, but cannot easily generalize to other, related tasks, or they need large amounts of data to do so. In this blog post, Yann LeCun and Ishan Misra of Facebook AI Research (FAIR) describe the current state of Self-Supervised Learning (SSL) and argue that it is the next step in the development of AI that uses fewer labels and can transfer knowledge faster than current systems. They suggest as a promising direction to build non-contrastive latent-variable predictive models, like VAEs, but ones that also provide high-quality latent representations for downstream tasks.

OUTLINE:
0:00 — Intro & Overview.
1:15 — Supervised Learning, Self-Supervised Learning, and Common Sense.
7:35 — Predicting Hidden Parts from Observed Parts.
17:50 — Self-Supervised Learning for Language vs Vision.
26:50 — Energy-Based Models.
30:15 — Joint-Embedding Models.
35:45 — Contrastive Methods.
43:45 — Latent-Variable Predictive Models and GANs.
55:00 — Summary & Conclusion.

Paper (Blog Post): https://ai.facebook.com/blog/self-supervised-learning-the-da…telligence.
My Video on BYOL: https://www.youtube.com/watch?v=YPfUiOMYOEE

ERRATA:
- The difference between loss and energy: Energy is for inference, loss is for training.
- The R(z) term is a regularizer that restricts the capacity of the latent variable. I think I said both of those things, but never together.
- The way I explain why BERT is contrastive is wrong. I haven’t figured out why just yet, though smile

Video approved by Antonio.

Abstract:

Continue reading “Yann LeCun — Self-Supervised Learning: The Dark Matter of Intelligence (FAIR Blog Post Explained)” | >

Scientists have been able to trap antimatter particles using a combination of electric and magnetic fields. Antiprotons have been stored for over a year, while antimatter electrons have been stored for shorter periods of time, due to their lower mass. In 2011, researchers at CERN announced that they had stored antihydrogen for over 1,000 seconds.

While scientists have been able to store and manipulate small quantities of antimatter, they have not been able to answer why antimatter is so rare in the universe. According to Einstein’s famous equation E = mc2, energy should convert into matter and antimatter in equal quantities. And, immediately after the Big Bang, there was a lot of energy. Accordingly, we should see as much antimatter as matter in our universe, and yet we don’t. This is a pressing unsolved mystery of modern physics.

According to Einstein’s equations, as well as other modern theories of antimatter, antimatter should be exactly the same as ordinary matter, with only the electric charges reversed. Thus, antimatter hydrogen should emit light just like ordinary hydrogen does, and with exactly the same wavelengths. In fact, an experiment showing exactly this behavior was reported in early 2020. This was a triumph for current theories, but meant no explanation for the universe’s preference of matter was found.

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A team of researchers from TU Delft managed to design one of the world’s most precise microchip sensors. The device can function at room temperature—a ‘holy grail’ for quantum technologies and sensing. Combining nanotechnology and machine learning inspired by nature’s spiderwebs, they were able to make a nanomechanical sensor vibrate in extreme isolation from everyday noise. This breakthrough, published in the Advanced Materials Rising Stars Issue, has implications for the study of gravity and dark matter as well as the fields of quantum internet, navigation and sensing.

One of the biggest challenges for studying vibrating objects at the smallest scale, like those used in sensors or quantum hardware, is how to keep ambient thermal noise from interacting with their fragile states. Quantum hardware for example is usually kept at near absolute zero (−273.15°C) temperatures, and refrigerators cost half a million euros apiece. Researchers from TU Delft created a web-shaped microchip sensor that resonates extremely well in isolation from room temperature noise. Among other applications, their discovery will make building quantum devices much more affordable.

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