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Twisted graphene has become the big thing in physics

quantamagazine.org

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Re: Twisted graphene has become the big thing in physics

#101

Post by zamalek »

fsh wrote: post #54
alanz1223 wrote: post #33

Holy guac, room temperature superconductivity seems almost science fiction-y but just imagine the disruption it would make. I would be particularly excited to experience how much electric motors and energy transfer/storage and conversion would improve.

Apparently they reached superconductivity at 3K. Hardly room temperature.

The thing is they can use it to understand superconductivity because there are vastly fewer variables involved. It could lead to room-temperature superconductivity, assuming it even exists.

Re: Twisted graphene has become the big thing in physics

#102

Post by sparkpy724 »

YorkshireSeason wrote: post #55
georgeburdell wrote: post #47

Earlier quoted context omitted.

Pretty typical of academia. Grad students also don't normally get Nobels

And for good reason. A responsible supervisor will typically give PhD students tasks that he has already "kind-of / sort-of" worked out as feasible. I once read the following recommendation for how to set dissertation subjects, I can't recall by whom. - BSc thesis: what I can do over lunch - Master thesis: what I could do in an afternoon - PhD thesis: what I could do in a week (Here the figures don't mean typing, pro…

This Heuristic is totally ludicrous, it reads like the rantings of someone who has never been to Grad school or done research.

Re: Twisted graphene has become the big thing in physics

#103

Post by village-idiot »

hanniabu wrote: post #94
village-idiot wrote: post #92

Earlier quoted context omitted.

The problem with asbestos wasn’t really the toxicity per se, it’s that the companies using it hid the toxicity to avoid having to do all the expensive safety steps that would let them use asbestos without killing people. We can avoid this with carbon nanotubes and similar if we’re honest about the risks and careful with how we handle them.

This will probably happen again given all the money that's on the line.

The fact that we’re talking about it here implies that we’re in a better place than we were a century ago.

Re: Twisted graphene has become the big thing in physics

#104

Post by Retra »

londons_explore wrote: post #78
kingkongjaffa wrote: post #67

Earlier quoted context omitted.

Also the cost of a equivalent superconductor network would be an order of magnitude more expensive that what is essentially room temperature metal cables with very basic technology - transformers, insulation, and switchgear.

A superconducting power network could be built today - it would consist of a pair of ceramic superconductors suspended in a liquid helium pipe, wrapped with 3 feet of insulation. Every few kilometers, one would need liquid helium pumping and chilling plants. Total helium losses to leakage wouldn't be too big. Electricity transmission efficiency would be reduced by all the chilling gear running, but still better than…

Is the amount of energy you spend building and maintaining that network more than what you're already losing to inefficiency?

Re: Twisted graphene has become the big thing in physics

#105

Post by astazangasta »

threetwoone321 wrote: post #90
deugtniet wrote: post #51

Earlier quoted context omitted.

Usually the grad student does most of the work, but the ideas and direction comes from the supervisor. It's normal that the supervisor funds, directs and communicates the work that's being done. More often than not, the supervisor has a better idea of the big picture and the implications of the work than the grad student, so it's natural that the supervisor talks to the press. For example, I'm a grad student, in a de…

In CS related fields, in particular ML and CV, this is absolutely not the usual situation except perhaps in the beginning of the PhD. Perhaps it's more common in fields where the research is done on top of a heavy investment in infrastructure/equipment that is lead by the professor, e.g. in physics and biology?

In my experience in biology new professors provide a lot of ideas, old professors just steal new ideas from their students and post docs.

Re: Twisted graphene has become the big thing in physics

#106

Post by ThrowawayR2 »

londons_explore wrote: post #78
kingkongjaffa wrote: post #67

Earlier quoted context omitted.

Also the cost of a equivalent superconductor network would be an order of magnitude more expensive that what is essentially room temperature metal cables with very basic technology - transformers, insulation, and switchgear.

A superconducting power network could be built today - it would consist of a pair of ceramic superconductors suspended in a liquid helium pipe, wrapped with 3 feet of insulation. Every few kilometers, one would need liquid helium pumping and chilling plants. Total helium losses to leakage wouldn't be too big. Electricity transmission efficiency would be reduced by all the chilling gear running, but still better than…

> ...suspended in a liquid helium pipe...

Where would we get enough helium to cover more than a small city's worth of power transmission lines?

Re: Twisted graphene has become the big thing in physics

#107

Post by logfromblammo »

golergka wrote: post #89

> Pablo Jarillo-Herrero is channeling some of his copious energy into a morning run, dodging startled pedestrians as he zips along, gradually disappearing into the distance. Can someone please write up TL;DR about the actual science without the details on what kind of coffee did the author sip while taking the interview?

When two sheets of graphene are stacked, and twisted with respect to one another, they form a metameterial, with properties partially dependent on the twist angle.

At a twist angle of 1.1 degrees, the energy required for an electron in one sheet to tunnel to the other sheet drops to zero.

The problem is that certain angles represent a lower-energy state than others, so twisting to a magic angle also requires overcoming some buckling and creasing in the individual sheets, that allow regions to locally align to a non-magic angle (like zero degrees). This confounds measurements of the properties of the metamaterial.

Certain angles have been shown to exhibit superconductivity. While less useful than previously discovered superconductors for the purpose of moving electrons, these are more useful for studying superconductivity itself, because the superconductor is 2.5d, composed of a single type of atom, each with identical bond configurations. A lot of the variables that appear in other superconductors drop out.

Re: Twisted graphene has become the big thing in physics

#108

Post by dasil003 »

village-idiot wrote: post #103
hanniabu wrote: post #94

Earlier quoted context omitted.

This will probably happen again given all the money that's on the line.

The fact that we’re talking about it here implies that we’re in a better place than we were a century ago.

A century ago yes, fifty years ago I'm not so sure, thirty years ago almost certainly not.

Re: Twisted graphene has become the big thing in physics

#109

Post by naasking »

danharaj wrote: post #99
naasking wrote: post #97

Earlier quoted context omitted.

Profitability at time X is a pretty decent heuristic for whether something is worth doing at time X.

How do you know that? Unknown unknowns.

Unknown unknowns are more likely to cause problems and delay completion, not accelerate development.

Re: Twisted graphene has become the big thing in physics

#110

Post by jacquesm »

m12k wrote: post #63
scotradamus wrote: post #27

Earlier quoted context omitted.

You're forgetting the two most important; energy storage and transport.

Yeah, imagine if we could more or less losslessly transfer electricity over vast distances. Massive renewable energy farms could be built wherever there was sun/wind/rivers whether the energy consumers are close or not. Energy could be sent to pump water into reservoirs as huge centralized batteries. The problem with 'what happens when the sun isn't shining/the wind isn't blowing' could be sidestepped because it's al…

I find it hard to tell if you're serious or not. To a rough approximation this is exactly how it works today.
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