Why Do Spin 1/2 Particles Behave Like a Twisted Ribbon?

  • Thread starter Edward Green
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In summary, Richard Feynman tells the barmaid a story about the concept of spin in quantum particles, using a trick with a stein and a ribbon as an analogy. He explains that particles with spin 1/2 behave similarly to the stein with the ribbon tied to it, coming back to their original position after two full turns but not one. He also shares with her why this behavior is unique to spin 1/2 particles and not others.
  • #1
Edward Green
The first two vanish into the back room to play a game of darts,
leaving the third to chat up the barmaid. After emptying a stein, he
pulls a bit of ribbon from his pocket and entertains her with a trick
whereby he ties the ribbon to the handle, twists the stein around two
full turns, and then magically untwists the ribbon without moving the
stein. He tells her how particles he studies have a property called
"spin", and that particles whose spin is 1/2 actually behave like the
stein with the ribbon tied to it: coming back where they started only
after two, but not one, full turns. Feynman then leans closer, and
conspiratorially whispers to her why (in language a barmaid can
understand), just spin 1/2 particles act this way, and not other
particles.

What story does the Feynman tell the barmaid?
 
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  • #2
Edward Green wrote:

> The first two vanish into the back room to play a game of darts,
> leaving the third to chat up the barmaid. After emptying a stein, he
> pulls a bit of ribbon from his pocket and entertains her with a trick
> whereby he ties the ribbon to the handle, twists the stein around two
> full turns, and then magically untwists the ribbon without moving the
> stein. He tells her how particles he studies have a property called
> "spin", and that particles whose spin is 1/2 actually behave like the
> stein with the ribbon tied to it: coming back where they started only
> after two, but not one, full turns. Feynman then leans closer, and
> conspiratorially whispers to her why (in language a barmaid can
> understand), just spin 1/2 particles act this way, and not other
> particles.
>
> What story does the Feynman tell the barmaid?


Ah ha he tells her : The trick is one of the other Feynmans sneaks out of
the back room and untwist the ribbon when she isn't looking. The quantum
particles are not spinning so calling this property spin is also a trick."

This makes the barmaid think "All physics is crap. But hey those guys make
plenty of money. Right?"

--
You do realize...
 
  • #3
Edward Green wrote:
> The first two vanish into the back room to play a game of darts,
> leaving the third to chat up the barmaid. After emptying a stein, he
> pulls a bit of ribbon from his pocket and entertains her with a trick
> whereby he ties the ribbon to the handle, twists the stein around two
> full turns, and then magically untwists the ribbon without moving the
> stein. He tells her how particles he studies have a property called
> "spin", and that particles whose spin is 1/2 actually behave like the
> stein with the ribbon tied to it: coming back where they started only
> after two, but not one, full turns. Feynman then leans closer, and
> conspiratorially whispers to her why (in language a barmaid can
> understand), just spin 1/2 particles act this way, and not other
> particles.
>
> What story does the Feynman tell the barmaid?


A spin as described where the Feynman theorest is the only allowed
answered is a quite simple story.

"A spin to the stein takes the steinist out of all."

A story where the particle never quite entertains the state in
question. A transverse.

Why spin 1/2 exists is the stein. A large effect making the surface the
particle as opposed to the geometric center. Causing all dilemma to
vanish. Gravity all.
 
  • #4
Edward Green said:
The first two vanish into the back room to play a game of darts,
leaving the third to chat up the barmaid. After emptying a stein, he
pulls a bit of ribbon from his pocket and entertains her with a trick
whereby he ties the ribbon to the handle, twists the stein around two
full turns, and then magically untwists the ribbon without moving the
stein. He tells her how particles he studies have a property called
"spin", and that particles whose spin is 1/2 actually behave like the
stein with the ribbon tied to it: coming back where they started only
after two, but not one, full turns. Feynman then leans closer, and
conspiratorially whispers to her why (in language a barmaid can
understand), just spin 1/2 particles act this way, and not other
particles.

What story does the Feynman tell the barmaid?

He gives her his telephone number & map to his home... "See you after work dear lass." :-p
 

FAQ: Why Do Spin 1/2 Particles Behave Like a Twisted Ribbon?

What is the concept behind "Three Feynmans walk into a bar"?

"Three Feynmans walk into a bar" is a hypothetical scenario that is used to explain the concept of quantum mechanics. It involves three versions of the renowned physicist, Richard Feynman, entering a bar and encountering different outcomes based on the laws of quantum mechanics.

Who came up with the idea of "Three Feynmans walk into a bar"?

The idea of "Three Feynmans walk into a bar" was originally proposed by physicist Richard Feynman himself in a lecture he gave in 1965. It has since been used as a thought experiment to help explain the complexities of quantum mechanics.

What is the purpose of using this scenario in explaining quantum mechanics?

The purpose of using "Three Feynmans walk into a bar" is to demonstrate the concept of superposition, where multiple states or outcomes can exist simultaneously until observed. It also helps to illustrate the idea of parallel universes and the concept of the observer affecting the outcome of an experiment.

Is "Three Feynmans walk into a bar" a real experiment or just a thought experiment?

This scenario is purely a thought experiment and has not been conducted in real life. It is used as a tool to help people understand the principles of quantum mechanics, rather than being a practical experiment.

What are some real-life applications of the principles illustrated in "Three Feynmans walk into a bar"?

The principles of superposition and observer effect, as shown in "Three Feynmans walk into a bar", have real-life applications in fields such as quantum computing, cryptography, and quantum teleportation. They also play a role in understanding the behavior of particles at the quantum level.

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