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Tsung-Dao Lee, physicist who challenged a law of nature, has died

nytimes.com

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Re: Tsung-Dao Lee, physicist who challenged a law of nature, has died

#61

Post by Koshkin »

lokimedes wrote: post #38
KwisatzHaderack wrote: post #20

> Lee became Dr. Fermi’s sole doctoral student in theoretical physics, meeting with him every week. It was an extraordinary learning experience, partly because of Dr. Fermi’s teaching technique, which Dr. Lee explained in the 2007 interview with the Nobel Institute. “‘You see,’ he said, ‘there are things that I would like to know,’” Dr. Lee recalled Dr. Fermi saying. “‘Lee, why don’t you look up and give me a lecture…

Pope without pontification!

Indeed, Fermi was called "the Pope of physics."

Fermi’s “intuito fenomenale” — phenomenal intuition — and his near infallibility in predicting the results of experiments were characteristics that prompted colleagues at the University of Rome to designate him “the Pope.”

Re: Tsung-Dao Lee, physicist who challenged a law of nature, has died

#62

Post by meroes »

perihelions wrote: post #31
DonaldFisk wrote: post #30

Earlier quoted context omitted.

What if they draw a number line with smaller numbers on the right and larger numbers on the left?

Indeed. There's nothing you possibly draw on paper that answers the question, in isolation. A diagram on paper means exactly the same thing if you simultaneously (i) flip it, and (ii) flip your mental interpretation if it. Or: if you run a software program on a raster image, there exists a different program that returns identical output given an input image which is mirror-flipped copy of the first one. (It's just th…

But we can distinguish i and -i by convention and keep consistent right? Akin to sending the distant alien a sample? It’s in the abstract that we can’t really tell them apart. But as soon as we are given any kind of starting point to form a convention, like the first mathematical textbook tells us which is i and which is -i, we have enough?

I think of an unlabeled, unconnected graph of two vertices. If I just pick one and call it A say by pointing to it, that’s enough. The trick is to do it for limited communication partners like the alien right?

Re: Tsung-Dao Lee, physicist who challenged a law of nature, has died

#63

Post by AaronM »

DonaldFisk wrote: post #30
AaronM wrote: post #28

Earlier quoted context omitted.

I thought about this for a bit. One easy to use explanation for left and right is a number line. Smaller numbers are on the left and larger numbers are on the right. It's still an assumption that alien species would count that way.

What if they draw a number line with smaller numbers on the right and larger numbers on the left?

Have them project an imaginary line from where they stand and in the direction they are facing. Have them mark the numbers 1 2 3 in the ground as they walk forward. Now have them stand facing the number two. Now you say if you are standing left side of the line looking left to right the numbers would go 3,2,1 if you are standing on the right side looking left to right the numbers would go 1,2,3

Edit: it's a bit silly though, I think if they could understand our language well enough to convey complex scientific ideas like an atom and its size, then smart people could probably find a good way to convey direction

Re: Tsung-Dao Lee, physicist who challenged a law of nature, has died

#64

Post by AaronM »

jodacola wrote: post #29
AaronM wrote: post #28

Earlier quoted context omitted.

I thought about this for a bit. One easy to use explanation for left and right is a number line. Smaller numbers are on the left and larger numbers are on the right. It's still an assumption that alien species would count that way.

I think this still illustrates the problem, though: where is the start of the number line? Perhaps this alien species has a right-to-left written language. Or top to bottom. How would one help orient the alien to the left to right numbering system used in this language? Very interesting thought experiment while drinking my coffee this morning!

I added a reply further up that attempts to explain my thought process

Re: Tsung-Dao Lee, physicist who challenged a law of nature, has died

#65

Post by AaronM »

perihelions wrote: post #31
DonaldFisk wrote: post #30

Earlier quoted context omitted.

What if they draw a number line with smaller numbers on the right and larger numbers on the left?

Indeed. There's nothing you possibly draw on paper that answers the question, in isolation. A diagram on paper means exactly the same thing if you simultaneously (i) flip it, and (ii) flip your mental interpretation if it. Or: if you run a software program on a raster image, there exists a different program that returns identical output given an input image which is mirror-flipped copy of the first one. (It's just th…

I attempted to explain my thought process further up

Re: Tsung-Dao Lee, physicist who challenged a law of nature, has died

#66

Post by raincole »

dotancohen wrote: post #55
snarkconjecture wrote: post #47

Earlier quoted context omitted.

It's the magnetic field that has the arbitrary sign convention. You can't determine the direction of a magnetic field from observations without using the right hand rule.

You don't have to know the sign, you could tell which way the electrons are going. We tell the aliens: you take all sorts of organics with liquid inside (on earth we typically use a lemon, but other organics will do), and put a stake of element 29 in one side and a stake of element 30 in the other. You then connect them with a length of element 29. Keep trying different organics until you find one that works. They mi…

I'd suggest you to re-read your parent comment. They already explained it concisely but you seem to be a bit to caught up in this lemon battary idea.

Re: Tsung-Dao Lee, physicist who challenged a law of nature, has died

#67

Post by raincole »

AaronM wrote: post #63
DonaldFisk wrote: post #30

Earlier quoted context omitted.

What if they draw a number line with smaller numbers on the right and larger numbers on the left?

Have them project an imaginary line from where they stand and in the direction they are facing. Have them mark the numbers 1 2 3 in the ground as they walk forward. Now have them stand facing the number two. Now you say if you are standing left side of the line looking left to right the numbers would go 3,2,1 if you are standing on the right side looking left to right the numbers would go 1,2,3 Edit: it's a bit silly…

> it's a bit silly though, I think if they could understand our language well enough to convey complex scientific ideas like an atom and its size, then smart people could probably find a good way to convey direction

You completely missed the point of the original thought experiment. The whole experiment already assumes that the Martian understands the concept of direction perfectly. That's the premise of it.

The hard part is to convey which direction is which. It's a completely different thing from the concept of direction.

It's not about Martians is so stupid and we need to try very hard to make them even understand what direction is. It's about whether there is a universal and fundamental (as fundamental as elementary particles) reference to distinquish left and right.

> Now you say if you are standing left side of the line looking left to right the numbers would go 3,2,1 if you are standing on the right side looking left to right the numbers would go 1,2,3

The Martian doesn't know how to "looking left to right". He doesn't know which side is left. That's the whole point.

Re: Tsung-Dao Lee, physicist who challenged a law of nature, has died

#68

Post by verzali »

noworld wrote: post #49
samanator wrote: post #17

Earlier quoted context omitted.

You can't use cancellation or heavenly bodies: "He is far away, or in some strange location, and he cannot see anything we can see. For instance, we cannot say, “Look at Ursa major; now see how those stars are arranged. What we mean by ‘right’ is …” We are only allowed to telephone him."

"imagine that we were talking to a Martian"

" he cannot see anything we can see. For instance, we cannot say, “Look at Ursa major; now see how those stars are arranged"

Re: Tsung-Dao Lee, physicist who challenged a law of nature, has died

#70

Post by Gunax »

Modified3019 wrote: post #13
perihelions wrote: post #12

Feynman wrote a exceptionally clear explanation of this experiment and what it meant: - "To illustrate the whole problem still more clearly, imagine that we were talking to a Martian, or someone very far away, by telephone. We are not allowed to send him any actual samples to inspect; for instance, if we could send light, we could send him right-hand circularly polarized light and say, “That is right-hand light—just…

“Try to teach an alien on a telephone about left and right” actually sounds like a fun game to try with a class full of kids. I would solve this particular circumstance by using the andromeda galaxy (“the closest galaxy”) as a reference, but it definitely stumped me for a bit.

I would love to try it, but I think the problem is hard enough to explain to an adult. I think it's difficult to describe the constraints. I've tried to explain this problem to adults and they just didn't really get it and the problem sounds like either a riddle or a bunch of nonsense rather than a physics problem with deep implications for the laws of nature.
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