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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

#51

Post by deugtniet »

intenex wrote: post #37

Fairly shocking to me that Yuan Cao received literally a single glancing mention here, but he was clearly the one who actually made the pivotal discovery, and is the first author on the Nature paper ( https://www.nature.com/articles/nature26154 ), and was the one named to the Nature 10 in 2018 for his discovery. Really mind boggling that this entire piece focuses all the attention on his supervisor and almost neglect…

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 department where my supervisor would talk to the press on work that I would have done.

Re: Twisted graphene has become the big thing in physics

#52

Post by gingabriska »

soulofmischief wrote: post #34
rubyn00bie wrote: post #19

Earlier quoted context omitted.

I don’t think I’m talking about perpetual motion at all... When I say never loses a charge I don’t mean it’s limitless capacity. I mean it could be charged 1,000,000 times without any affect on the capacity of the system? Maybe a better way to say it, a battery that does not degrade with each use. Superconductors allow for the perfect transfer of electrons without any loss? So like if I had a giant earth sized graphe…

Ok I see, by "not losing its charge" you meant not wearing down from repeated use. Technically speaking the charge would be the amount of electrical potential energy stored in the device. This system is still subject to the laws of thermodynamics, however. AFAIK ideal superconductivity does not exist outside of theoretical physics, just as ideal platonic solids do not exist in the real world. Things get bumpy close u…

Charge is not amount of electric potential.

Charge is a property of matter which causes experiencing a force when placed in an electric field.

Strength of the electric field is electric potential.

And charges arrange in some form under this field which wouldn't be so in absense of this field and how tight is that form depends on the strength of electric field. And this can be used to perform some work but this is not storing charge as the total charge before arrangement is same as total charge after arrangement there is no new charge added. We are storing electric field here.

In all such storage devices, strength of the field goes down after sometimes.

No I don't know how it can help in case of batteries but assuming you use capacitor to store electric field the leakage can be decreased by using better insulation which in many cases is thicker and the capacitor is limited to some specific size, if you can decrease the surface area of the conductive plates, you are able to use thicker insulation which results in lower leakage so graphene can help here as it's just one atom thick.

Re: Twisted graphene has become the big thing in physics

#53

Post by fsh »

tigershark wrote: post #42
peanutz454 wrote: post #35

Earlier quoted context omitted.

I understand what superconductivity is and how it can revolutionize things in general. But why those things in particular? So transport for example - better maglev trains?

A huge amount of energy is wasted distributing electricity for 10s of thousands km. I am not sure how it can help storage though, even if you theoretically can let the electricity spin in a closed loop forever the energy density seems way too low to me.

A standard 380 kV power line has a loss on the order of 1% per 100 km. Unless you want to span large continents, this doesn't seem like a big limitation at all.

Re: Twisted graphene has become the big thing in physics

#54

Post by fsh »

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.

Re: Twisted graphene has become the big thing in physics

#55

Post by YorkshireSeason »

georgeburdell wrote: post #47
intenex wrote: post #37

Fairly shocking to me that Yuan Cao received literally a single glancing mention here, but he was clearly the one who actually made the pivotal discovery, and is the first author on the Nature paper ( https://www.nature.com/articles/nature26154 ), and was the one named to the Nature 10 in 2018 for his discovery. Really mind boggling that this entire piece focuses all the attention on his supervisor and almost neglect…

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, programming etc, but the core intellectual work). After having supervised nearly 200 theses are BSc, Masters and PhD level, I must agree, this is a pretty great heuristic.

Note: there are exceptions. Some PhD theses go way beyond this, but those are rare. I have no idea about Yuan Cao's work, discussed here.

Re: Twisted graphene has become the big thing in physics

#57

Post by sagitariusrex »

>Even without superconductivity, ordinary computers and other electronics could get a huge boost in performance versus cost from twistronics, due to the fact that entire complex electronic circuits could in theory be built into a few sheets of pure carbon, without needing a dozen or more complexly etched layers of challenging materials common to today’s chips.

Re: Twisted graphene has become the big thing in physics

#59

Post by [deleted] »

deugtniet wrote: post #51
intenex wrote: post #37

Fairly shocking to me that Yuan Cao received literally a single glancing mention here, but he was clearly the one who actually made the pivotal discovery, and is the first author on the Nature paper ( https://www.nature.com/articles/nature26154 ), and was the one named to the Nature 10 in 2018 for his discovery. Really mind boggling that this entire piece focuses all the attention on his supervisor and almost neglect…

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…

[deleted]

Re: Twisted graphene has become the big thing in physics

#60

Post by homarp »

plutonorm wrote: post #56

Where'd all the intelligent comments go? Hackernews used to be a cut above when it came to an intelligent comments section. Where'd all those people go, is there a new place to hang out?

If you know th new place, you know the first rule of the new place...

A nice intro to superconductors http://www.superconductors.org/uses.htm

the history of graphene, the "next best thing" since forever: https://graphene-flagship.eu/material/Pages/The-history-of-g... (previous HN discussion - https://news.ycombinator.com/item?id=8751946 )

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