eig

In case anyone is looking for the youtube video, it's pretty impressive:

https://youtu.be/abi84lnjNV4

You don’t need to force the halves together quickly to start a chain reaction, but you do need to put them together fast to create a bomb. If it’s not fast enough you will get a “Fizzle” [0] where some chain reaction is occurring but not over a small enough timespan to make a bomb or to stop the material from disintegrating itself. A similar slow chain reaction process is used to control energy release in nuclear power plants.

[0] - https://en.m.wikipedia.org/wiki/Nuclear_chain_reaction#Prede...

There’s a big difference in customer psychology when you’re dealing with a luxury good vs tech products.

You can tell electrons are flowing in a superconductor by measuring the magnetic field induced around them.

The 500kW almost certainly includes the cooling losses. The chips alone theoretically consume power roughly according to the Landauer-Von Neumann limit, which would be less than microwatts for the shoebox they describe. In real life it’ll be more due to the switching flux and EM radiation generated but I think still much less than a watt. Liquid helium cooling and pumping through the chip is super inefficient which is where 99% of the energy is going.

An MRI machine is a fancy 3D camera. Is this "3D Deep-DSP Model" so different from the processing Samsung did on their phones?

I can say that most radiologists would not want a computer trying to fix poor scan data. If the underlying data is bad, they would have recommend an orthogonal imaging abnormality. "I don't know" is a possible response radiologists can give. Trying to add training data to "clean up" an image would bias the read towards "normal".

A few months ago there were articles going around about how Samsung galaxy phones were upscaling images of the Moon using AI [0]. Essentially, the model was artificially adding landmarks and details based on its training set when the real image quality was too poor to make out details.

Needless to say, AI upscaling as described in this article would be a nightmare for radiologists. 90% of radiology is confirming the absence of disease when image quality is high, and asking for complementary studies when image quality is low. With AI enhanced images that look "normal", how can the radiologist ever say "I can confirm there is no brain bleed" when the computer might be incorrectly adding "normal" details when compensating for poor image quality?

[0] - https://news.ycombinator.com/item?id=35136167

I fabricobbled a liquid nitrogen generator using a cryocooler at home using the same design as Ben at Applied Science [0]. It works very well, I've used it to make liquid nitrogen ice cream many times. It's just slow so I run it overnight.

Applied Science is fantastic channel if you haven't seen it. He's also on HN.

OP's design is much more impressive and hard to build than using a Stirling cryocooler like I did.

[0] - https://www.youtube.com/watch?v=7PWESWqhD8s

If you want to see a video series of someone making this lathe design from scratch (right from casting aluminum), here it is: https://www.youtube.com/watch?v=LBuUOO3qn30

I was amazed at the accuracy and surface finish he could achieve with homemade parts.

Previous discussion here: https://news.ycombinator.com/item?id=40097637

This unfortunately looks like little more than hot air.

This triggers all the sketchy science alarms:

-New fundamental force

-Explains warp drive (??)

-Requires exquisite measurement methods and cancelling out all other interfering forces (which inevitably they won’t do well)

-Ex-big institute head scientist to lend credence

-No supporting scientific papers in a reputed journal

-Big claim of legitimacy based on a patent being granted

This is far sketchier than even Ranga Das’s superconductivity claims.

Recovering from supine position is a known tough problem in bipedal robots. It makes sense that they would want to show off this capability.

You could theoretically subclassify cancers all the way down to individual gene mutations, and even then there is heterogeny within one cancer itself. That is the idea behind "personalized medicine" though it's being distorted by hype.

However, medicine is practical, and tries to draw boundaries where different therapies help differently or where there are different pathophysiology going on.

The article was able to draw a new additional boundary. Its relevance is yet to be confirmed with its phenotype or druggability. If it turns out to be useful either in predicting therapy or outcome, it'll stick and oncologists will learn it.

This process has already been repeated a lot in the hematological cancers, where previously cancers like "Hodgkin's lymphoma" have been subdivided as we made new treatments and discovered the individual pathways.

While the parent commenter did exaggerate, they are correct in their idea. You could subclassify cancers all the way down to individual gene mutations, and even then there is heterogeny within the cancer itself.

Medicine tries to draw boundaries where different therapies help differently or where there is different pathophysiology going on. The article was able to draw one such additional boundary. Its relevance is yet to be confirmed with its phenotype or druggability.

Does point (b) actually matter? I thought the location of center of mass and center of thrust doesn't matter in a non-gimballed rocket according to the Pendulum Rocket Fallacy (https://en.wikipedia.org/wiki/Rocket#Pendulum_rocket_fallacy).

I don't see how this is different from how any distributor of goods does business.

Nobody bats an eye when the local grocery store (a distributor) is spending more than 70% of its revenue to buy the goods from their suppliers. It's also expected that suppliers/factories don't pass on those payments back to the farmers.

You can interact with a working demonstration booth of this at MIT. That apparatus had an initial backwards torque when you turned on the suction, but no constant torque pushing it the other way once everything hit steady state. I wonder why these authors seem to have gotten a different result...

You got it- the sucking in comes from all directions.

In response to your first question, the water doesn’t add negative angular momentum because the whole system we are conserving is the sprinkler body and the moving water together. The sum must just be zero in both cases. We can track a single drop of water in case two (Feynman) to see how the conservation works. At the start the drop is at zero angular momentum since it is stationary in the tank. It then passes through the whole Sprinkler mechanism (and whatever s-curves there are) and ends up at the suction drain at the center of the sprinkler also at zero angular momentum. Therefore no matter what happened it could not have applied a net torque to the sprinkler, no matter the path it took to get to the drain.

Contrast with case 1, the regular sprinkler, where the water drop starts at zero angular momentum (pumped from the center of the sprinkler) and ends with positive angular momentum (spinning away from the center) therefore it must have applied an opposing net torque at some point in its journey to the body of the sprinkler, which spins.

The most intuitive explanation for the Feynman sprinkler I can think of is conservation of angular momentum.

In the pump-out case, the water adds positive angular momentum when it flies out, so the sprinkler body must add negative angular momentum (constant torque) to have conservation.

In the Feynman suck-in case, the water drains from the base of the sprinkler without any angular momentum, so the sprinkler head does not have to add an opposite angular momentum (feel a constant torque).

This isn't really a new question... every cardiologist was taught the Windkessel model of the cardiovascular system, and it's taught in med school today (I am a med student). We specifically learned it as a RC filter (aortic compliance and vascular resistance) attached to an impulse train (the heartbeats). It makes a great homework problem to think about how the blood pressure waveform changes with calcification.

We do actually. In the car industry they have to test airbag systems in closed roads and special warehouses that the companies built themselves.

Reminds me of a classic short story by none other than Isaac Asimov:

https://en.wikipedia.org/wiki/The_Fun_They_Had

https://www.bartlettschools.org/pdf/TheFunTheyHad.pdf

People have been debating the utility and potential isolation of automated personalized learning from before we even had real computers!

This is Sony, so their electrical engineers clearly know what they are doing.

But at the same time I can't understand how such a thing works using pure white noise. Feynman famously described (and disproved) a similar energy-harvesting device [0] except one that uses mechanical noise and a mechanical rectifier instead of the electrical noise and electrical rectifier of Sony. He showed that such a device will eventually stop working due to the second law of thermodynamics. Why doesn't that happen in the Sony chip?

[0] - https://en.wikipedia.org/wiki/Brownian_ratchet

Yep, that’s strong diamagnetism.

This video (https://sciencecast.org/casts/suc384jly50n) showing the Meissner effect should be the easiest to replicate: just send a sample to another lab and put it over a large magnet.

As far as I know, the only explanations for this occurring is room temp superconductivity, or a strong diamagnetism (which would also be very cool to see)!

That's not the video I'm referring to. It is a different experiment from Fig 4b in the paper, which is showing magnetic levitation.

I agree with swamp40: the video you linked is not demonstrating the Meissner effect, and is just showing Lenz's law.

A sister paper [0] has a photo of the material exhibiting the Meisner effect and levitating over a magnet, and claims to have a video too.

Either they blatantly photoshopped the photo or they actually made a room temperature super conductor. I can’t see how the could have made a subtle mistake that resulted in magnetic levitation at room temp without making a superconductor.

[0] - https://arxiv.org/abs/2307.12037

Thanks for sharing your experience. To what extent do you trust Finkel‘s writing here?

I don’t know either, and hopefully someone here in journalism can comment on how serious it is to do what Finkel did.

I like how the New Yorker Book Review article (recently on HN [0]) reviewed both the book as well as the author. I thought that was a fair assessment- bringing the prior journalistic issues to light while also discussing the merits of the book.

[0]-https://news.ycombinator.com/item?id=36449581