Single-Particle Interference for BIG objects-what does it mean for a lay person?

Viva-Diva

Hi All,

I am a new member and not a physicist. A long time back a physicst friend of mine told me about the single particel inteference experimnet and I was fascinated.

Today I learnt that this exist even for macroscopic objects. http://www.physorg.com/news78650511.html

Whay could this mean for the layperson.....that we can exist in two places at once!? That we are waves too? So teleporting can actually be a reality??

Please excuse me if my questions are stupid (the last time I did physics was in highschool)

Please enligtem me, your explainations will be greatly appreciated!

Thanks:-)
Viva-Diva

Viva-Diva

Any one able to help me out please ?

thanks
Vica-Diva

ZapperZ

There is a HUGE difference between what quantum particles can do, and what you and I (classical objects) can do. If such quantum behavior are that easy to occur, we would have seen it easily by now, and it would not be so strange.

It also means that many pseudoscience and mystical claims using quantum mechanics as a justification are also bogus, because no such connection has been established.

So don't worry yourself over such things. Just look at your world. Nothing has changed.

Zz.

Viva-Diva

but a Silicon dot is BIG.....it is 10 million times bigger than a quantum object.
Please don't burst my bubble...:-) I am so happy thinking what all would be possible after this great discovery!

if it applys to a big macroscopic object...why wouldn't it apply to us?

ZapperZ

Then would you like to try tunneling through a wall, or interfering with yourself?

Zz.

Viva-Diva

Tuneeling through a wall would be a great idea:-)

meopemuk

Yes, macroscopic objects can exist in two places at once. Or they can be in a superposition of two very different states, such as "alive" and "dead" states of the famous Schroedinger cat. However, this state superposition exists only before the measurement is done. When we actually measure things we find them either "here" or "there" and we find them either "alive" or "dead". We never find them in the superposition state.

Eugene.

Viva-Diva

Thanks Eugene,

I dont understand what you mean by 'before' measuremnet is done. Before measurement is done, there are infinite possibilities where an object can be because we don't even know.

But apparently in this particular experimnet, they showed tghat particels exist in 2 places after measurement was done. Isn't it?

I apologise if my questions seem too stupid.

tahnks
Viva-Diva

meopemuk

That's right. We don't even know. That's why there is nothing mysterious in quantum-mechanical superposition.

I can't comment about this particular experiment with droplets. I would need to read beyond this press-release to understand what was actually done there. However, in the classic double-slit experiment with electrons or photons the particles never exist in 2 places after the measurement. Each particle hits the scintillating screen or the photographic plate in one place. So, the measurement of the particle position is unambiguous. The entire "controversy" is about what the particle was doing while we were not watching. Did the particle pass through one slit or through both slits? These are metaphysical questions, because they ask about something we did not observe. As you correctly pointed out, one can answer "I don't know" or "I don't care" and be done with it.

Eugene.

Viva-Diva

Eugene,

Thanks again. Do you guys believe in metaphysics?
Have you seen the movie, "what the bleep do we know?" (a very very badly amde film, but the content of it was very interesting nevertheless).

What do you physicits tink of such stuff?

Viva-Diva

Doc Al

It's crap. Almost pure nonsense. Including a very misleading presentation of quantum mechanics.

Viva-Diva

But ALL of them were scientist and doctors , some from Harvard and Stanford.

meopemuk

In my opinion, physics is an experimental science. The role of theoretical physics is to predict results of experiments. We really shouldn't ask for more than that. We shouldn't give too much credence to our theoretical models and "mechanisms" which go beyond observable effects and try to say what the system is "actually" doing while we are not watching. Such models and "mechanisms" can be successful mathematical tools, but it would be unwise to assign any physical meaning to them.

For example, the most precise and comprehensive description of quantum effects is provided by state vectors and Hermitian operators in the Hilbert space. However, nobody can seriously believe that the Hilbert space is a physical entity.

Eugene.

Hans de Vries

This experiment shows that classical physics can produce effects which we usually
expect only from quantum mechanical systems. A particle (a 1 mm oil droplet) diffracted
via it's wavefunction. Quite interesting though.


Regards, Hans

Demystifier

Only one of them was a quantum physicist. What he said was OK. But it was not directly related to the rest of the movie.

Demystifier

I would!
To show that the interpretation of QM I adopt is correct.
(That physical objects, both microscopic and macroscopic, are not their wave functions.)

fleem

Throwing a baseball in the air is quantum mechanics, and so is eating a sandwich. When we are children we learn to generally understand a lot of these particular experiments in quantum mechanics. What we did not notice as children is that there are certain behaviors that are very subtle in high energy experiments (like throwing a ball or eating a sandwich) which become more clear when we do low energy experiments (like slowly rotating a dish of super cold helium or noting the individual photons striking a detector).

Classical mechanics is an estimate of the average behavior of a lot of low-energy interactions acting in unison. The total energy is high, but each separate interaction is low energy. We see that the low energy interactions don't follow that "average" behavior described by classical mechanics.

Any experiment demonstrating a behavior of quantum mechanics that seems odd to us (because we didn't notice it as children) will involve very low energy. There are some experiments that produce results that can be seen with the naked eye, so to speak. Quantum vortices, and interference patterns of individual particles, are two examples. So no matter how clever your contraption (and we've no idea how to make one yet), the only way to take advantage of, for example, quantum tunneling on a macroscopic scale (cause tunneling to work in unison for a lot of particles) would be to cool all the particles in the entire experiment WAY down. Next, we'd have to somehow individually associate every particle in the subject to be transported with a position in the destination. Then we'd have to figure out a way to cause all the particles to tunnel at the same time. In other words, it ain't gonna happen real soon.