A room-temperature superconductor? New developments • Hacker News Board

Re: A room-temperature superconductor? New developments

#781

Post by jacquesm » Wed, Aug 02, 2023, 2:45 PM UTC

cogman10 wrote: post #633

fsh wrote: post #516

Earlier quoted context omitted.

None of the things you listed are limited by the conductors in them. The efficiency of high voltage AC power lines is limited by capacitive coupling to ground. Battery charging is limited by the cell chemistry. CPU heat output is limited by the resistance of the semiconductors. Turns out metals (in particular copper) are already incredibly good conductors.

> The efficiency of high voltage AC power lines is limited by capacitive coupling to ground. And to this point, HVDC has been slowly rising as a viable alternative beyond just undersea transmission. A mistaken belief is that AC is more efficient than DC. What AC is is more easy to transform from one voltage to another (until somewhat recently). That makes it easier to run AC at 1 MV and then step it down to 240V for…

AC is also easier to switch under load.

Re: A room-temperature superconductor? New developments

#782

Post by chrismorgan » Wed, Aug 02, 2023, 2:55 PM UTC

Beldin wrote: post #735

sheepscreek wrote: post #644

Earlier quoted context omitted.

But it is. A significant part of electronics engineering is dedicated to heat dissipation. So what do we stand to gain? At least a slight improvement in efficiency of transmission. And a huge improvement due to simpler heat dissipation needs. So this might mean way faster battery charging - like 500 miles worth of charge in 5 mins. We’re mainly limited by how hot the batteries get during charging.

We're about halfway there already, just by cooling: 250km in under 4 min (1). (1) https://www.tue.nl/en/news-and-events/news-overview/13-07-20...

I love that electric vehicle charging can be expressed in speeds (that is, distance divided by time). 250km/4min is 3750km/h, a touch over Mach π.

Re: A room-temperature superconductor? New developments

#783

Post by mwbajor » Wed, Aug 02, 2023, 3:00 PM UTC

cogman10 wrote: post #633

fsh wrote: post #516

Earlier quoted context omitted.

None of the things you listed are limited by the conductors in them. The efficiency of high voltage AC power lines is limited by capacitive coupling to ground. Battery charging is limited by the cell chemistry. CPU heat output is limited by the resistance of the semiconductors. Turns out metals (in particular copper) are already incredibly good conductors.

> The efficiency of high voltage AC power lines is limited by capacitive coupling to ground. And to this point, HVDC has been slowly rising as a viable alternative beyond just undersea transmission. A mistaken belief is that AC is more efficient than DC. What AC is is more easy to transform from one voltage to another (until somewhat recently). That makes it easier to run AC at 1 MV and then step it down to 240V for…

"A mistaken belief is that AC is more efficient than DC. What AC is is more easy to transform from one voltage to another (until somewhat recently). That makes it easier to run AC at 1 MV and then step it down to 240V for residential applications."

DC is also used because a conductor can carry more current per kg than AC due to not having any skin loss. You can use smaller wires, less metal, less dollars.

Re: A room-temperature superconductor? New developments

#784

Post by whimsicalism » Wed, Aug 02, 2023, 3:15 PM UTC

dirtyid wrote: post #754

robot_no_421 wrote: post #647

Earlier quoted context omitted.

China is facing severe demographic issues for the next 20-30 years due to their terribly short sighted one-child policy and their poor immigration rates. Literally the opposite of what you're saying. Where on earth did you get your facts from?

Not Zeihan tier demographic analysis which is a start. PRC currently generating ~5m STEM per year, aka OECD combined, multiple times more than US has ability to train or brain drain. And relatively proven ability to coordinate talent. Project that out next 20-30s from previous 20-30 years of birth rate and PRC on trend to add 50M-100M STEM to workforce, just STEM, not including other skilled workers, which is the gre…

Thank you for writing it out, I think people are sort of in denial and have been for a solid decade now.

Arguments about China’s inevitable collapse are more about comfort than about the an reality, because as you have mentioned if you think at all seriously about the demographics argument it just does not make sense.

I think the biggest risk for China demographically is if their aging population translates to an extremely conservative, risk-averse government/society that harms their technological progress, as has happened with Japan (ie. top multinationals stuck in the 80s with fax machines, paper, etc.)

Re: A room-temperature superconductor? New developments

#785

Post by robotguy » Wed, Aug 02, 2023, 3:15 PM UTC

PaulHoule wrote: post #777

jtchang wrote: post #418

The ramifications of the inflection point we are currently at is mind boggling. I had a hard time explaining this last night but we may very well be witnessing the beginnings of a technological transformation era much like when the p-n junction was invented. From the 1940s standpoint it would be hard to envision all we had today. - Lossless transport of energy - Batteries that don't take any time to recharge - Faster…

To kill your buzz: Liquid Nitrogen superconductors shocked the world in 1987 but have hardly changed it. They have some applications but we don't have transoceanic power cables, superconducting supercomputers, MAGLEV trains everywhere, etc. You could have made the case that the cost of liquid helium cooling put traditional superconductors out of reach for most applications, but liquid nitrogen cooling is not difficul…

Reminds me of a story: I was in college physics in fall '89 and our professor was telling us how he and his son spent the summer in Alaska prospecting for whatever material was all the rage in superconductors at the time. He was explaining that when superconductors broke the liquid nitrogen temperature, it was a game changer. He said "If you buy it by the gallon, liquid nitrogen is cheaper than beer."

To which a student replied "You buy beer by the gallon?"

Re: A room-temperature superconductor? New developments

#786

Post by whimsicalism » Wed, Aug 02, 2023, 3:19 PM UTC

Gibbon1 wrote: post #770

whimsicalism wrote: post #525

Earlier quoted context omitted.

I see a country with triple the young people we do.

It's a mistake to think in terms of the US only. Because unlike China the US doesn't think that way. And if you include the core part of Team America, it's even steven.

Who is the core part of team America? Because the anglosphere doesn’t even it out I don’t think and Western Europe is not unequivocally on our side in US-China industry competition.

Re: A room-temperature superconductor? New developments

#787

Post by PaulHoule » Wed, Aug 02, 2023, 3:45 PM UTC

robotguy wrote: post #785

PaulHoule wrote: post #777

Earlier quoted context omitted.

To kill your buzz: Liquid Nitrogen superconductors shocked the world in 1987 but have hardly changed it. They have some applications but we don't have transoceanic power cables, superconducting supercomputers, MAGLEV trains everywhere, etc. You could have made the case that the cost of liquid helium cooling put traditional superconductors out of reach for most applications, but liquid nitrogen cooling is not difficul…

Reminds me of a story: I was in college physics in fall '89 and our professor was telling us how he and his son spent the summer in Alaska prospecting for whatever material was all the rage in superconductors at the time. He was explaining that when superconductors broke the liquid nitrogen temperature, it was a game changer. He said "If you buy it by the gallon, liquid nitrogen is cheaper than beer." To which a stud…

ever bought a keg?

Re: A room-temperature superconductor? New developments

#788

Post by jerf » Wed, Aug 02, 2023, 4:06 PM UTC

babyshake wrote: post #727

jerf wrote: post #497

Earlier quoted context omitted.

Unfortunately, while you can indeed build hoverboards with superconductors and they do work, you still need a magnetic surface for it to ride over. I don't believe generalized hoverboards that will work on all surfaces like BttF are possible.

Wouldn't a hoverboard with rockets on the bottom and back work? I'm not saying it's feasible, just that it's utilizing the same basic science as jets and space travel.

I think if you look up the smallest rocket that is capable of even lifting you off the ground on an instantaneous basis, let alone over time, you are going to be somewhat surprised at the size. I think you will also decide you don't particularly want to be at point-blank range to this rocket when it goes.

I mean, theoretically, if you loosen the definition of "hoverboard" enough, it might be possible to create something that hovers with you on it, but I don't think you'd accept it as a substitute for the movie hoverboard.

Re: A room-temperature superconductor? New developments

#789

Post by klyrs » Wed, Aug 02, 2023, 4:14 PM UTC

OkayPhysicist wrote: post #585

klyrs wrote: post #237

Earlier quoted context omitted.

If you can extract work from the field generated by the supercurrent, it must come from somewhere. Small supercurrents make small fields, so things like adiabatic CPUs seem interesting.

Can you extract work from a constant magnetic field? As I remember my physics education, constant magnetic fields don't do any work, since they apply a force perpendicular to the direction of motion.

I'm not a physicist, but I play with circuitry... two nearby loops of wire are magnetically coupled. If one is a superconductor with some stored current, and the other is a normal conductor with some resistance, then it stands to reason that the supercurrent will burn heat off in the resistive loop.

Re: A room-temperature superconductor? New developments

#790

Post by iancmceachern » Wed, Aug 02, 2023, 4:20 PM UTC

burnished wrote: post #730

iancmceachern wrote: post #683

Earlier quoted context omitted.

What things are we going to do with this material in the next 5 years? What things that I buy and use will be made better?

You know those joke buzzer/shocker rings? Well, they're going to get really, really good.

Just what I've always wanted!