Quantum weirdness

[entropie]

So finally I make the step. What are your opinions and most of all what do you know about Dr.Quantum's physics lecture about the "double slit experiment":

YouTube - Dr Quantum - Double Slit Experiment (http://www.youtube.com/watch?v=DfPeprQ7oGc)

[entropie]

No thrown gauntlets to real geeks here, real physics here ! xD

[ygolo]

The destructive part of the interference pattern... that's what convinces me.

Otherwise, I would say things like, "well the particles could be spinning in weird ways, etc."

Also, I am not sure what you want to discuss.

If you're looking for an opportunity to simply discuss and wonder about quantum mechanics and the sheer oddness of it. I'm all for it.

[entropie]

I have not much to discuss, yet; I am currently reading some mathematics about QED. I tend to fall asleep, while reading but it is not the topic that is uninteresting, it is the mass amount of text :).

The Book is from the Feynman Lectures , Part 3.

I posted this thread to see, if someone else is intrested in the topic and knows some intresting theories already. If I can help it and not fall asleep during reading, I will be up to speed in 2 or 3 weeks

[Samuel De Mazarin]

I consider the double-slit experiment, from my non-mathematical background, very simply one more in a growing series of experiments which are warning us that some of the emphasis in physics needs to be shifted to biology and neuroscience in order to understand what happens when we perceive 'physical' events... it's also vindicating some of Kantian theory (along with other similar philosophical theories of the past).

[Jack Flak]

It's undeniably weird, but take a look at history. Things tend to turn out rational after all.

[Samuel De Mazarin]

The Double Slit Experiment - my crazy night in Amsterdam

[ygolo]

What are people's ideas for why wave functions collapse under observation?

[nozflubber]

well, if it didn't, we wouldn't have two vital things: Continuity and a Static Fabric to swim in. Everything would be a wonderous mess

[Little Linguist]

I *am* quantum weirdness, but it has nothing to do with physics. If you have question regarding this topic, feel free to ask. :D

Okay, please continue....

[runvardh]

I *am* quantum weirdness, but it has nothing to do with physics. If you have question regarding this topic, feel free to ask. :D

Okay, please continue....

Yes, you are a small package and a little strange. :D

[Little Linguist]

Yes, you are a small package and a little strange. :D

Hey, sweet, thanks! I'll take that as a compliment! :D

[ygolo]

I'm watching this now, seems like its going to be good:

In your Face Quantum Mechanics

Edit:Excellent video!
An improvement on Bell's Experiment that is MUCH simpler, a very satisfactory explanation on why the wave function collapses, and even an exposition of randomness from a quantum mechanical perspective.

[Angry Ayrab]

The worst class of my undergrad life was classical quantum mechanics only because I delayed it till my senior year and the last time I took a math class was partial differential equations during my freshman year. The theories I could gobble up in a heartbeat but some of the mathematical manipulations were just so ridiculous without using mathematica or some other math program. I remember one take home question with calculating the dipole from 1S to 3D orbital in the hydrogen atom taking over six pages of calculus with my microfont handwriting (over three days of work on the problem mainly reviewing my calc skills).

The coolest thing about the double slit experiment is that it shat on the idea that we knew everything their was to know about the world, which was hottly becoming a common belief in the late 19th century.

want to have some fun at home, get a cheap laser pointer, shove it between some heavy books to keep it on, and point it at a white flat wall. then get two credit cards (I used text books to stabalize them so they didn't wobble) and have them make an extremely thin (sub millimeter) slit that the laser can see through and then stabalize everything that way. Go to the wall, and you will see a single slit diffraction pattern. Next hang a rock from a string and then hang the string from a platform and have it intersect the laser coming from your slit right in the middle. next do the credit card thing again to the string in the middle to make a double slit. They have to be very close to each other and they have to be close in size and maybe about 2-3feet from the first slit or less if you want, but atleast ten feet away from the wall and wallah, you just proved that light is a wave. Without having two guys to help you or some creative stabalization methods, this easier said than done, but what is more fun than a in home double slit experiment reproduction. If you are interested, I can give more detailed plans or do a you tube video and even show you how to get the cathode ray tube out of an old CRT monitor or tube tv and use the phosphorous screen as a detector for the electron part of the experiment.

Oh yeah and the diffraction pattern will be very small unless your wall is really really really far away and you have a really bad ass laser. have fun.

EDIT: By the way, the heavy handed mathematical manipulations in the class seem to have a knack for taking out all the fun in these theories.

[Babylon Candle]

The worst class of my undergrad life was classical quantum mechanics only because I delayed it till my senior year and the last time I took a math class was partial differential equations during my freshman year. The theories I could gobble up in a heartbeat but some of the mathematical manipulations were just so ridiculous without using mathematica or some other math program. I remember one take home question with calculating the dipole from 1S to 3D orbital in the hydrogen atom taking over six pages of calculus with my microfont handwriting (over three days of work on the problem mainly reviewing my calc skills).

The coolest thing about the double slit experiment is that it shat on the idea that we knew everything their was to know about the world, which was hottly becoming a common belief in the late 19th century.

want to have some fun at home, get a cheap laser pointer, shove it between some heavy books to keep it on, and point it at a white flat wall. then get two credit cards (I used text books to stabalize them so they didn't wobble) and have them make an extremely thin (sub millimeter) slit that the laser can see through and then stabalize everything that way. Go to the wall, and you will see a single slit diffraction pattern. Next hang a rock from a string and then hang the string from a platform and have it intersect the laser coming from your slit right in the middle. next do the credit card thing again to the string in the middle to make a double slit. They have to be very close to each other and they have to be close in size and maybe about 2-3feet from the first slit or less if you want, but atleast ten feet away from the wall and wallah, you just proved that light is a wave. Without having two guys to help you or some creative stabalization methods, this easier said than done, but what is more fun than a in home double slit experiment reproduction. If you are interested, I can give more detailed plans or do a you tube video and even show you how to get the cathode ray tube out of an old CRT monitor or tube tv and use the phosphorous screen as a detector for the electron part of the experiment.

Oh yeah and the diffraction pattern will be very small unless your wall is really really really far away and you have a really bad ass laser. have fun.

EDIT: By the way, the heavy handed mathematical manipulations in the class seem to have a knack for taking out all the fun in these theories.

i wish there were ways to learn more about physics without needing a PhD in math...

im absolutely horrible at calculus! ...yet i so deeply wish to understand what physics says about the nature of our universe. the hardest part of trying to understand physics on a "made easy level" is that its often wrong. you end up with crap like "what the bleep do we know" which is just physics heresy according to people who know what the hell they are talking about....

physics made easy: that isnt actually wrong or trying to further some new age cult.... thatd be a good book!

[entropie]

Try "The Feynman Lectures on Physics - Volume III - Quantum Mechanics" by Richard Feynman. You can read it without knowing anything from vol. I + II and without knowing anything about math and physics.

It is written pretty clearly and intresting.

[ygolo]

All most all of Feynman's material is accessible to lay-people, even QED (http://www.amazon.com/QED-Strange-Theory-Light-Matter/dp/0691024170), his own theory, is very accessible.

I also recommend Six Not-So-Easy Pieces (http://www.amazon.com/Six-Not-So-Easy-Pieces-Helix-Books/dp/0201328429) (also Six Easy Pieces: Essentials of Physics Explained by Its Most Brilliant Teacher (http://www.amazon.com/Six-Easy-Pieces-Essentials-Explained/dp/0201408252))

Not that this focuses on quantum mechanics, but you'll have an amazingly good micture of the "Standard Model" of physics after reading these.

However, as far as math goes. I suggest you learn about Hibert Spaces at least (just enough to interpret the inner-product style notation). It will save you a lot of trouble in the long run.

[Angry Ayrab]

i wish there were ways to learn more about physics without needing a PhD in math...

im absolutely horrible at calculus! ...yet i so deeply wish to understand what physics says about the nature of our universe. the hardest part of trying to understand physics on a "made easy level" is that its often wrong. you end up with crap like "what the bleep do we know" which is just physics heresy according to people who know what the hell they are talking about....

physics made easy: that isnt actually wrong or trying to further some new age cult.... thatd be a good book!

Lol, technically, its (the video) a pretty good layman example of the double slit experiment in the most genral (ENxP's most favorite thing) way. You get the gist of the results. Also, just to make you happier, you must understand the theory first before you try to explain it mathematically, only issue is you won't pass the class if you don't know the math, because all the questions in these classes are usually solving schrodinger equation... and using fourier transforms or some other thing made to piss off people of a biological background who are not super grounded in differentials.

[Angry Ayrab]

All most all of Feynman's material is accessible to lay-people, even QED (http://www.amazon.com/QED-Strange-Theory-Light-Matter/dp/0691024170), his own theory, is very accessible.

I also recommend Six Not-So-Easy Pieces (http://www.amazon.com/Six-Not-So-Easy-Pieces-Helix-Books/dp/0201328429) (also Six Easy Pieces: Essentials of Physics Explained by Its Most Brilliant Teacher (http://www.amazon.com/Six-Easy-Pieces-Essentials-Explained/dp/0201408252))

Not that this focuses on quantum mechanics, but you'll have an amazingly good micture of the "Standard Model" of physics after reading these.

However, as far as math goes. I suggest you learn about Hibert Spaces at least (just enough to interpret the inner-product style notation). It will save you a lot of trouble in the long run.

I think he is a biochemistry major if I am correct and if so he would be forced to take all the pre-requisites for physical chemistry which is like baby quantum which should have him well on his way to understanding it.

[Lateralus]

What are people's ideas for why wave functions collapse under observation?
It's not possible to be completely disconnected and still observe an event. I think that our presence alters the event in some fashion, but how exactly? That's beyond my understanding, though I wouldn't be surprised to learn that it's somehow related to the Heisenberg Uncertainty Principle in the 10th or 11th dimension, or something along those lines.

[Angry Ayrab]

It's not possible to be completely disconnected and still observe an event. I think that our presence alters the event in some fashion, but how exactly? That's beyond my understanding, though I wouldn't be surprised to learn that it's somehow related to the Heisenberg Uncertainty Principle in the 10th or 11th dimension, or something along those lines.

Yeah, that is what the heisenberg is explaining, but what is this 10th and 11th demension. If you know position with a high degree of certainty, you can't know velocity with a high degree of certainty, and vice versa. Also, it works for time and energy. But forgive me I never took the extra demensions thing... could you explain.

[Lateralus]

Yeah, that is what the heisenberg is explaining, but what is this 10th and 11th demension. If you know position with a high degree of certainty, you can't know velocity with a high degree of certainty, and vice versa. Also, it works for time and energy. But forgive me I never took the extra demensions thing... could you explain.
I'm sure you've heard of M-theory and Superstring theory.

[ygolo]

It's not possible to be completely disconnected and still observe an event. I think that our presence alters the event in some fashion, but how exactly? That's beyond my understanding, though I wouldn't be surprised to learn that it's somehow related to the Heisenberg Uncertainty Principle in the 10th or 11th dimension, or something along those lines.

I like Sidney Coleman's explanation (in the "in your face" video). Basically, the wave function doesn't actually collapse, but since the measuring aparatus is itself a quantum-mechanical system, it is always true the measuement will measure a collapsed state.

The cat actually is in a superposition of dead and alive states, but being quantum mechanical systems ourselves, we will notice him in either a completely alive or completely dead state (as amazingly sci-fi-ish as that seems).

[Lateralus]

I like Sidney Coleman's explanation (in the "in your face" video). Basically, the wave function doesn't actually collapse, but since the measuring aparatus is itself a quantum-mechanical system, it is always true the measuement will measure a collapsed state.

The cat actually is in a superposition of dead and alive states, but being quantum mechanical systems ourselves, we will notice him in either a completely alive or completely dead state (as amazingly sci-fi-ish as that seems).
Interesting idea. I haven't seen that video...gonna watch it now.

[Angry Ayrab]

Honestly, I think I am the last human on earth to not have read about m or string theory. I know this sounds douchebaggish and maybe retarded, but late at night in the hospital when I have nothing to do. I go to the abandanoned chart board and sit their and work on my own grand unified theory... complete with horrendous looking mathematical explanations and all. Obviously, I haven't yet got it figured out.

So this string and m-theory thing, am I really missing out some total coolness?

[entropie]

It is an attempt to visualize what until now was described through mathematics, the quantum world.

[Lateralus]

Honestly, I think I am the last human on earth to not have read about m or string theory. I know this sounds douchebaggish and maybe retarded, but late at night in the hospital when I have nothing to do. I go to the abandanoned chart board and sit their and work on my own grand unified theory... complete with horrendous looking mathematical explanations and all. Obviously, I haven't yet got it figured out.

So this string and m-theory thing, am I really missing out some total coolness?
It's not the most interesting subject to me (but still fairly so), probably part of the reason I'm not a theoretical physicist. I only mentioned them because you asked about the extra dimensions.

[Angry Ayrab]

Man I hate you guys now. I just started watching the Nova special on M and string theory and I am just gritting my teeth because they are just claiming things and I am wanting to see some math... Lol, I feel like a total douche now because I always bash mathematical proof.

[Lateralus]

Man I hate you guys now. I just started watching the Nova special on M and string theory and I am just gritting my teeth because they are just claiming things and I am wanting to see some math... Lol, I feel like a total douche now because I always bash mathematical proof.
I've never seen any sort of mathematical proof for those theories, but I imagine it would probably be pretty boring...and I love math.

[Babylon Candle]

I've never seen any sort of mathematical proof for those theories, but I imagine it would probably be pretty boring...and I love math.

i was under the impression that string theory/m theory although not testable/provable.... had mathematical proofs that make them more than just fantasy???

1. ???string theory is necessary because splitting photons does not always give off the same particles (there must be stuff smaller?)???
2. working the math, its discovered that these strings need to move in more than 4 dimensions (the 4th being time)
3. these 11 or 12 dimensions being included in the theory make it "m theory" complete with our universe being the "membrane" stretched string???

i think im on some sort of general direction that may end up in the vicinity of the right track...but i need a little help. :)

[ygolo]

i was under the impression that string theory/m theory although not testable/provable.... had mathematical proofs that make them more than just fantasy???

1. ???string theory is necessary because splitting photons does not always give off the same particles (there must be stuff smaller?)???
2. working the math, its discovered that these strings need to move in more than 4 dimensions (the 4th being time)
3. these 11 or 12 dimensions being included in the theory make it "m theory" complete with our universe being the "membrane" stretched string???

i think im on some sort of general direction that may end up in the vicinity of the right track...but i need a little help. :)

M-Theory is not really my favorite subject in physics, but I believe the string theories all came about due to trying to unify gravity with the Standard Model (which already acounts for many of the smaller particles).

The "official" webste for string theory:
The Official String Theory Web Site (http://superstringtheory.com/index.html)

When the Large Hadron Collider (http://lhc.web.cern.ch/lhc/) starts giving us data, there is hope that we will get data relavent to the Standard Model, and perhaps the string theories and other such things.

EDIT:By "we" I mean the human race--not that I have anything to do with it.

[Lateralus]

When the Large Hadron Collider (http://lhc.web.cern.ch/lhc/) starts giving us data, there is hope that we will get data relavent to the Standard Model, and perhaps the string theories and other such things.
That thing is really cool. :nerd: I wonder if they give tours...I'll be in France next spring and that would be awesome to see.

[ygolo]

This is indeed a good source:
Ket space (http://farside.ph.utexas.edu/teaching/qm/lectures/node7.html)
Bra space (http://farside.ph.utexas.edu/teaching/qm/lectures/node8.html)

[Angry Ayrab]

This is indeed a good source:
Ket space (http://farside.ph.utexas.edu/teaching/qm/lectures/node7.html)
Bra space (http://farside.ph.utexas.edu/teaching/qm/lectures/node8.html)


These are fundamental and you better know this before going to class. Nice post.

[the.blanket.on.top]

I'm sure you've heard of M-theory and Superstring theory.

http://img401.imageshack.us/img401/8816/mtheorycroppedyw9.jpg

YouTube - Parallel Universes (http://www.youtube.com/watch?v=2_vpEyE6rug&feature=related)

[ygolo]

OK. I now have enough interest in M-theory and the string theories, that I want to learn the Math (otherwise I'll continue to think of it as B.S).

Does anyone know good sources?

[noigmn]

I watched the videos too. Those sensationalised documentaries always make me skeptical.

So is M-Theory still around, does it promise much, and can anyone give a good clear basis of the mathematics and perceived reality of what the theory means?

I hear opinions either way all the time, and I know there is obvious unexplained order in the standard model and the need to provide connection between various scientific theories, but are these new theories based on thought experiments that run close to known reality, or a mathematical attempt to find a formula that fits all known reality?

ie. is it maths based or science based? Just remembering things like Einstein's best work were theoretical physics and based mainly on concepts built from anomalies in experiments. Not a mathematical search for a God formula.

An interesting thought on this topic also is what does a God Formula mean? Does it solve everything, or give us an idea of where to look next. Say for example you had the God Formula and wanted to model the weather. This doesn't sound too hard, you have the God Formula. You get the maximum amount of information you can get for every particle on Earth at a set time and start the modelling system. Even if all the original information was accurate and could be measured simultaneously, you'd get done by Heisenberg's and wouldn't know where any particle is a microsecond later. Five seconds later, you will know so little about the system, that the original idea was pointless.

Or say something like turbulence. We have the Navier-Stokes equation. It models it. So do we have the answers? Not really. Or quantum mechanics. We have Schrodinger's wave equation. Now take a 1000 particle system and model it... I can't think what an 11 dimensional equation is going to be like to find any solutions for with a complex system.