Schroedinger's cat is missing

[Swede]

Can someone 'splain the quantum duality of photons to a drunk moron like me.

[Don_G]

1. Not Through A Tunnel Diode

:evilgrin:

[TXlib]

2. Are you sure?

Did you collapse the wave function?

The duality is this:

Everything has some wavelike nature, and some particlelike nature.

The wavelength decreases as the object's size (momentum, if you want to be picky) increases, so for large objects, the wavelength is SOOOOO small, no wavelike phenomena can be observed.

However, quantum-scale particles (protons, neutrons, electrons, photons, etc) can exhibit both particle-like and wavelike properties, depending on what you are measuring.

In light for example:

You can diffract light through a slit, and create an interference pattern through two slits. This is a wavelike property.

You can knock electrons out of atoms with high energy light (UV, X-rays, gamma rays). This is a particlelike property.

It's no surprise that massive particles like neutrons, electrons and protons can also knock electrons out of atoms, too, but you can also get them to diffract! They typically have MUCH smaller wavelengths than most light (EM radiation) you might normally encounter, so they are useful for probing really small things: electron microscopy, neutron diffraction to determine crystallographic structure, etc.

The kicker is this:

When you set up the two-slit experiment, and use a dim light source so that only one photon at a time goes through the slits, you STILL get the diffraction pattern.

So what the hell is the photon interfering with? Itself! Its own "probability wave".

So is a photon (or any other quantum particle) a particle or a wave? Well, it's both, and it's neither.

Whatever it REALLY is, we have no intuition to grasp. It's like trying to explain the color red to a person blind since birth. But the macroscopic world models of waves and particles each do a reasonable job of describing quantum particles' behavior in different regimes.

Don't worry. I've studied this stuff for over 15 years, and it STILL makes my head hurt sometimes.

[TXlib]

3. Follow up

I'd recommend "QED: The Strange Theory of Matter and Light" by Richard Feynmann, if you want more weirdness.

[JanMichael]

4. You have just earned the...

... "DON'T EVER POST SHIT LIKE THAT IN THE LOUNGE AGAIN FREAKAZOID SCIENCE THING!!!"

Instant headache...

[Rabrrrrrr]

5. Then don't be asking about

feynman diagrams, describing particles moving backward in time...

[blondeatlast]

7. Well, at least not on Friday or Saturday nights, anyway!

:evilgrin:

[Swede]

10. Well if they're moving backward in time

I'm really asking this tommorow.

[JanMichael]

11. At least not when I'm toasted!

Normally I find these conversations fascinating but now? Porn, I want porn...NO! Not that, I want the Revolution! No...I want my back-ache to go away...

Oh crap!

[Another Bill C.]

8. This is a pretty good explanation.

I worked on large excimer lasers for a while and when you study what goes on inside, you get a better understanding of this. You also burn your eyes out (cataracts) rather quickly.

[SOteric]

12. Dude.

*swoon*

[TXlib]

39. Wow... did I just turn somebody *on* with physics???

[Fridays Child]

45. So, would diffraction and interference be like...

...the expanding concentric circle pattern that occurs when you throw a stone into the water and how, if you threw two stones into the water, each concentric circle pattern would be altered by the other?

edit: grammar

[TXlib]

47. well

Yes, the interacting ripples from two stones demonstrate interference.

As for diffraction, that would be demonstrated by the ripples bending into the "shadow" of a large stone.

http://www.wikipedia.org/wiki/Ripple_tank

[ewagner]

49. Great explanation!

I've been pursuing particle physics as a hobby for about 10 years.

Can't handle the math but the nature of it is something to keep my mind off of all the other crap going on.

[TXlib]

51. I can recommend a whole bunch of good books.

[blondeatlast]

6. . . .Or is it? Or, maybe it is half missing and half present?

Aye, there's the rub.

[Swede]

9. So why does the observer change the result of the experiment

[DS1]

14. because at an atomic level

measurement requires changing the environment.

in the cat example, opening the box could introduce more oxygen and make the flame burn faster, or the gust of wind could blow the flame out, or the cat could jump out, etc. you can't ever know the exact status of the cat, just as you can't ever know the position of an electron (heh, caught a typo there, election, how fitting)

[Swede]

19. No the point of the experiment was not opening the box

it was the dual state of quantum physics. Light is both a partical and an electromagnetic wave,which is impossible.

[TheZoo]

13. An epic poem

Schroedinger, Erwin! Professor of physics!
Wrote daring equations! Confounded his critics!
(Not bad, eh? Don't worry. This part of the verse
Starts off pretty good, but it gets a lot worse.)
Win saw that the theory that Newton'd invented
By Einstein's discov'ries had been badly dented.
What now? wailed his colleagues. Said Erwin, "Don't panic,
No grease monkey I, but a quantum mechanic.
Consider electrons. Now, these teeny articles
Are sometimes like waves, and then sometimes like particles.
If that's not confusing, the nuclear dance
Of electrons and suchlike is governed by chance!
No sweat, though--my theory permits us to judge
Where some of 'em is and the rest of 'em was."
Not everyone bought this. It threatened to wreck
The comforting linkage of cause and effect.
E'en Einstein had doubts, and so Schroedinger tried
To tell him what quantum mechanics implied.
Said Win to Al, "Brother, suppose we've a cat,
And inside a tube we have put that cat at--
Along with a solitaire deck and some Fritos,
A bottle of Night Train, a couple mosquitoes
(Or something else rhyming) and, oh, if you got 'em,
One vial prussic acid, one decaying ottom
Or atom--whatever--but when it emits,
A trigger device blasts the vial into bits
Which snuffs our poor kitty. The odds of this crime
Are 50 to 50 per hour each time.
The cylinder's sealed. The hour's passed away. Is
Our pussy still purring--or pushing up daisies?
Now, you'd say the cat either lives or it don't
But quantum mechanics is stubborn and won't.
Statistically speaking, the cat (goes the joke),
Is half a cat breathing and half a cat croaked.
To some this may seem a ridiculous split,
But quantum mechanics must answer, "Tough @#&!
We may not know much, but one thing's fo' sho':
There's things in the cosmos that we cannot know.
Shine light on electrons--you'll cause them to swerve.
The act of observing disturbs the observed--
Which ruins your test. But then if there's no testing
To see if a particle's moving or resting
Why try to conjecture? Pure useless endeavor!
We know probability--certainty, never.'
The effect of this notion? I very much fear
'Twill make doubtful all things that were formerly clear.
Till soon the cat doctors will say in reports,
"We've just flipped a coin and we've learned he's a corpse."'
So saith Herr Erwin. Quoth Albert, "You're nuts.
God doesn't play dice with the universe, putz.
I'll prove it!" he said, and the Lord knows he tried--
In vain--until fin'ly he more or less died.
Win spoke at the funeral: "Listen, dear friends,
Sweet Al was my buddy. I must make amends.
Though he doubted my theory, I'll say of this saint:
Ten-to-one he's in heaven--but five bucks says he ain't."

[Mr. Brown of MD]

18. One of the funnier things I've seen recently

Do you know where that originated? Or is it something of yours?

-CollegeDude
Thinks the 'but' in the last line screws up the cadence

[TheZoo]

53. It's from Straight Dope

http://www.straightdope.com/classics/a1_122.html

[Ivory_Tower]

15. My favorite graffiti

Saw this on the wall in the basement of my Physics building when I was in college:

"Schroedinger may have slept here."

[Swede]

17. beeyoootiful

as we learn more and more we know less and less.

[TXlib]

40. I think it was supposed to be

"Heisenberg may or may not have slept here"

[Fridays Child]

46. But you can't know that with certainty.

:bounce:

[FloridaJudy]

52. Actually, he really did

But we don't know exactly where, or for how long...

[Ivory_Tower]

54. D'oh!!!

I thought something felt weird when I posted that. That's what I get for posting when I've had a few beers.

(Slinks away in embarrassment....)

[kodi]

16. only because you are not looking for him

that's the point of it.

[Swede]

20. the N on the Nebraska Cornhuskers helmet stands for.......

knoledge

[MercutioATC]

21. Guess it was alive....

.

[DrGonzoLives]

22. A photon exists in a superposition of one of two states

until it is observed, in which case the probablility field collapses and one state is "chosen" for lack of a better word.

[kodi]

23. because of observation, the universe wills it to exist.

so if you are not looking for it it don't exist. or out of sight, out of mind, and it appears this paradox drives some out of their minds as well.

[Swede]

24. Still begs the question,

How does the observer determine the state.

[kodi]

25. the doc just explained it,

the probability state is either 1 or zero under observation.

we're talking about mathematical functions whose answers can be only two states when under observation.

its either there or it isn't, and it isn't there if you aren't looking. which seems to be a rather demonic and twisted substantiation for an existentialist view and one which would give emmanuel kant a heart attack.

[Swede]

26. So the cat is dead and alive?

Counterintuitive as all get out. I just don't get it.

[BlueJazz]

27. Not being a smartass here.....

...but to your question "Is the cat dead or alive"
The answer is Yes

[kodi]

28. it has the potential to be either, observing turns potential to reality

not observing it removes its reality.

or interchange the word "potential" with "probability," it is that the probability state of <1 and >0 is not the "reality" state of it, that occurs when the action of observation impacts the probability, and probability =1 or 0. if you weren't looking at the cat, there would be no action towards demanding that the cat existed or not and the cat would remain in its "potential/probability" state of <1 and >0.

it is and it is not depending on whether you are looking at it or not.

the cat exists because you are observing it.

[Swede]

29. Now I understand............uh where's my cat?

[kodi]

34. ye of little faith, seek it and ye shall find it.

.

[TXlib]

44. The cat, if it's sentient, is an observer itself

So the experiment is rather moot.

But I've heard philosophers with just enough physics knowledge to be dangerous go 20 rounds on this very topic.

[FloridaJudy]

55. Shrodinger knew all about "thought experiments" but f*** all about cats

The cat is definately alive.

Against all odds, she's crouched there in the box, ready to claw out the eyes of the first theoretical physicist reckless enough to open it.

-OR-

She was *never* in the box to begin with! She squeezed out through a crack in the side, while the scientist was setting up the experiment.

I've known many physicists. They're smart. I've lived with many cats. They're smarter.

When it comes to survival, I'm putting my money on Miss Kitty!

P.S. I named my cat "Shrodinger". So sue me.

[Swede]

30. Now explain entropy and string theory

[Rabrrrrrr]

31. entropy is a measure of disorder

Whenever energy is transformed (burn coal to heat water to make steam to drive turbines to make electricity; drop an egg on the floor, etc.) some energy is lost in the process. It's why there can be no perpetual motion machines.

MCHawking has a song on entropy. Go here: http://www.mchawking.com/multimedia.php?page_function=mp3z

Sadly, you can't download the mp3s anymore from there due to their own bandwidth limitations, but you can surely find the song on kazaa or elsewhere, since they freely distributed.

Here are the lyrics for the song:

Entropy, how can I explain it? I'll take it frame by frame it,
to have you all jumping, shouting saying it.
Let's just say that it's a measure of disorder,
in a system that is closed, like with a border.
It's sorta, like a, well a measurement of randomness,
proposed in 1850 by a German, but wait I digress.
"What the fuck is entropy?", I here the people still exclaiming,
it seems I gotta start the explaining.

You ever drop an egg and on the floor you see it break?
You go and get a mop so you can clean up your mistake.
But did you ever stop to ponder why we know it's true,
if you drop a broken egg you will not get an egg that's new.

That's entropy or E-N-T-R-O to the P to the Y,
the reason why the sun will one day all burn out and die.
Order from disorder is a scientific rarity,
allow me to explain it with a little bit more clarity.
Did I say rarity? I meant impossibility,
at least in a closed system there will always be more entropy.
That's entropy and I hope that you're all down with it,
if you are here's your membership.

Chorus
You down with entropy?
Yeah, you know me! (x3)
Who's down with entropy?
Every last homey!

Verse 2
Defining entropy as disorder's not complete,
'cause disorder as a definition doesn't cover heat.
So my first definition I would now like to withdraw,
and offer one that fits thermodynamics second law.
First we need to understand that entropy is energy,
energy that can't be used to state it more specifically.
In a closed system entropy always goes up,
that's the second law, now you know what's up.

You can't win, you can't break even, you can't leave the game,
'cause entropy will take it all 'though it seems a shame.
The second law, as we now know, is quite clear to state,
that entropy must increase and not dissipate.

Creationists always try to use the second law,
to disprove evolution, but their theory has a flaw.
The second law is quite precise about where it applies,
only in a closed system must the entropy count rise.
The earth's not a closed system' it's powered by the sun,
so fuck the damn creationists, Doomsday get my gun!
That, in a nutshell, is what entropy's about,
you're now down with a discount.

[Swede]

32. Pssss, pssss Psssss anybody see my cat.

Sorry. I think I get all of this but I still don't understand it.

[Rabrrrrrr]

33. Perhaps the best idea is not to try to understand it

and let it be as it is. :shrug: Meaning, mayhaps you are trying to hard to understand it, and therefore are missing it. Basically, the world as we know it - the macro scale - is formed entirely from random events and chaos at the micro scale, which events coalesce together to give us stuff like cheese, planets, and light. There is a stastical and physics based chance that, at any moment, the cheese on your table might utterly dissipate and turn into something else (surely within the life of the cheese maybe one or two of its atoms WILL do this), but the probability is so small that within the history of the universe, it's probably never happened (unless we get into the infinite universes theory in which there are an infiniite number of universes in which this has happened, and also an infinite in number which it has not).

It's mind blowing and incredible and wondrous, and I'm often amazed and appalled that so few people care about stuff like this, for it is what makes us all.

[Swede]

36. mmmmmmmmmmm, cheese

[Mikimouse]

35. Schroedinger's cat is alive and well

and eating breakfast in my kitchen in this reality path:hi: :hippie: ;-)

[Iverson]

37. Schroedinger's cat is missing and not missing.

Dr. Gonzo's post (#22?) sums it up, but in case you are too drunk, here is the lite version.

At the subatomic level, normal (Newtonian) rules don't apply very well.

For something you haven't observed yet, reality's possibilities are describable as "wave functions" which all may apply until you take a peek.

Taking a peek makes one wave function survive, and all the rest break down and disappear.

The cat is both alive and not alive until you look; then one possibility persists while others break down.

Hope that helps. If not, take another swig and go back to Gonzo's note.

[Swede]

38. While we're at it, have gravitons been discovered?

Higg's bosun is there or quantum theory has a nasty surprise in the future.

[TXlib]

41. I think you mean Higg's boson

A bosun is a petty officer on a merchant ship who controls the work of other seamen.

huh huh... I said "seamen"... huh huh

[Swede]

48. I found both spellings on google

I read that it was named exactly because of it's maritime conneaction.

[TXlib]

50. Grrr... I made an apostrophe error

It's "Higgs Boson"

http://www.exploratorium.edu/origins/cern/ideas/higgs.html

A boson is a quantum particle with integral quantum spin number, as opposed to half-integral spin number, the fermions.

The higgs boson is the particle believed responsible for the symmetry breaking that gave rise to mass.

[TXlib]

42. And no, no compelling evidence for gravitons has yet been found.

[TXlib]

43. But we _did_ find the top quark some years back.