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Superconductor news: What’s claimed, and how strong the evidence seems to be

science.org

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Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#321

Post by blablabla123 »

jake_D wrote: post #314

1. In the video, they push the disc with a pen until it rolls over. They repeat it multiple times. It it were superconductive they could just position it in space without laying it on the magnets first. 2. The disc is not hovering. 3. The disc is damaged; one edge is thicker/heavier than the other. Thus causes the rolling. Notice that the heavier part always stays on the magnet. It it were superconductive they would…

With a "regular" magnetic field you cannot even do this, it would roll over continuously. At least one point needs to be actually fixed. Also if I remember correctly it's mentioned that not the whole probe is superconductive but just part of it.

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#322

Post by spaceman_2020 »

jonplackett wrote: post #11

If this material does just what they say it does, what would it revolutionise? Or as the article talks about, is this just a pointer at other possibilities that would be the real game changers?

Well for starters, you would never have to hear that awful fan noise from your computer :)

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#324

Post by [deleted] »

ummonk wrote: post #216
local_issues wrote: post #78

Earlier quoted context omitted.

Ding ding ding! We still don't know how bikes work, we have a pretty good but incomplete model for lift on airplanes, and no one has the faintest why Tylenol works. We should figure that out! But we can definitely keep using all the applications until then. (Except for Tylenol, we keep learning how bad that stuff is) EDIT: It won't let me post more, so here's the answers to responses. For sure! https://www.cbc.ca/new…

Nonsense. There's nothing incomplete about our model for lift on airplanes.

[deleted]

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#325

Post by jake_D »

blablabla123 wrote: post #321
jake_D wrote: post #314

1. In the video, they push the disc with a pen until it rolls over. They repeat it multiple times. It it were superconductive they could just position it in space without laying it on the magnets first. 2. The disc is not hovering. 3. The disc is damaged; one edge is thicker/heavier than the other. Thus causes the rolling. Notice that the heavier part always stays on the magnet. It it were superconductive they would…

With a "regular" magnetic field you cannot even do this, it would roll over continuously. At least one point needs to be actually fixed. Also if I remember correctly it's mentioned that not the whole probe is superconductive but just part of it.

It would not roll over continuously as it's affected by gravity as well. The heaviest part is at the bottom.

And if it's not completely superconductive, what stops it from not being completely magnetic? For all we know, only the thin part could be magnetic, being repelled from the magnet below.

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#326

Post by hinkley »

denimnerd42 wrote: post #312
hinkley wrote: post #250

Earlier quoted context omitted.

As a bit of an aside, most people don't know how bicycle wheels work. There's a whole section in https://en.wikipedia.org/wiki/The_Bicycle_Wheel that talks about how they actually work. It's not tension at the top, it's compression on the bottom.

what do you mean it's not tension at the top? did you misspeak? bicycle spokes are solely under tensile forces. they can't support compressive forces at all. i'm a hobbyist wheel builder and a once upon a time professional bicycle mechanic during hs & college. if you want to test this take nearly all the pretension out of your spokes and sit on your bike. feel which ones are taught and which ones are completely loose…

That book I linked has another name, “the wheel building bible”. Jobst Brandt earned an obituary in Bicycling magazine including quotes from his friend Tom Ritchey (one of the original mountain bike makers). Jobst was a bike fanatic and a mechanical engineer.

Bike spokes are not loose, they’re under substantial tension. Bolts, I just learned a couple weeks ago, work in the opposite way. A tightened bolt compresses the two pieces of metal together, and when you tug on them, the bolt doesn’t stretch more. The tension instead first cancels out some of the compressive force on the two pieces of metal, before the bolt ever feels more load.

Conversely, all the spokes on the wheel are under tension. When you put the wheel on a surface and push down, the compression cancels out some of the tension on the bottom of the wheel. Cancel out all of the tension, and the wheel turns into a potato chip if you don’t reload it exactly, perfectly on axis. IIRC, none of the prior models or theories for how a spoked wheel works could adequately explain how potato chipping happens. His does.

I used his book to build half a dozen wheels or so and the information it contained to fix many more.

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#327

Post by hinkley »

bradyd wrote: post #320
denimnerd42 wrote: post #312

Earlier quoted context omitted.

what do you mean it's not tension at the top? did you misspeak? bicycle spokes are solely under tensile forces. they can't support compressive forces at all. i'm a hobbyist wheel builder and a once upon a time professional bicycle mechanic during hs & college. if you want to test this take nearly all the pretension out of your spokes and sit on your bike. feel which ones are taught and which ones are completely loose…

They even make spokes that are rope https://berdspokes.com/pages/technology

I wonder if those have less or more breakin issues compared to spokes. With a spoke you have to reset the angle of the bend to the shortest distance between the hub and the rim. But with cables they have to settle in along their entire length.

Doesn’t change the answer. They’re still compressing. They’re just pretensioned.

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#328

Post by treme »

hcks wrote: post #59
rohan_ wrote: post #15

What do the "super forecasters" have to say about this? Was this predicted on prediction markets? Was the assumption of this tech existing already factored into prediction models?

Prediction markets say this will probably not replicate (and imo even overestimate the probability of replication)

link? interested in this wager

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#329

Post by jibe »

doctorwho42 wrote: post #315
BizarroLand wrote: post #207

Earlier quoted context omitted.

I wonder what learning the specific system by which bikes are balanced would teach us about the world or human beings? It's such a banal thing to be so fascinating.

It's the reason I got a degree in physics, if you have good professors - discussions like this cause you to break down the problem quite quickly in your head in a working model. Think force diagrams, but with a ton more math backing it up. I actually find the ice skate a better example than a bike. We have all the physics solved for bikes, it's a complicated system but so is everything in motion. Hence we assume a sp…

Ice skates aren't sharp bladed

Not sure how you meant that, but ice skates are sharp. Each edge of the blade is sharpened by grinding a hollow out of the center.

https://weekendwarriorshockey.com/how-sharp-should-my-skates...

Re: Superconductor news: What’s claimed, and how strong the evidence seems to be

#330

Post by denimnerd42 »

hinkley wrote: post #326
denimnerd42 wrote: post #312

Earlier quoted context omitted.

what do you mean it's not tension at the top? did you misspeak? bicycle spokes are solely under tensile forces. they can't support compressive forces at all. i'm a hobbyist wheel builder and a once upon a time professional bicycle mechanic during hs & college. if you want to test this take nearly all the pretension out of your spokes and sit on your bike. feel which ones are taught and which ones are completely loose…

That book I linked has another name, “the wheel building bible”. Jobst Brandt earned an obituary in Bicycling magazine including quotes from his friend Tom Ritchey (one of the original mountain bike makers). Jobst was a bike fanatic and a mechanical engineer. Bike spokes are not loose, they’re under substantial tension. Bolts, I just learned a couple weeks ago, work in the opposite way. A tightened bolt compresses th…

i own the book.. and also The Art of Wheelbuilding - Gerd Schraner

of course in a properly built wheel usually all the spoke are under tension...

i was just demonstrating the fact that the spokes on the upper half of the wheel are supporting the hub and are under greater tension than the bottom ones, the spokes on the bottom half of the wheel should remain in tension, but only through the fact that they are already under tension applied during the building of the wheel.

the fact that the wheel works by tension of the spokes becomes obviously apparent when you start to remove the pretension and then the spokes will feel loose on the bottom half. of course you'd never want to ride a wheel like that because it will quickly become out of true.. just like a walmart wheel.

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