electron emitter details for double slit experiment

I agree, what I was getting at is if light were quantized then the speed of communication between two entangled photons makes the speed of light seem pretty slow, ie. breaks the speed of light, which was the whole point of the EPR paradox to show that quantum mechanics is nonsense.

QCD describes the quantized states of matter (quarks) but doesn't imply that light is inherently quantized.

I think it can be looked at as just an extension of the Schrodinger equation to quark labelled vibrational states of matter.

"the Schrödinger equation is an equation that describes how the quantum state of a physical system varies."

cheers, Jamie

Of course it works to model, just like a 3D engine works to model, however that is based on polygons, this is not proof that we are constructed of polygons though, even if the PS3 does look realistic enough to convince some people otherwise. ;)

cheers, Jamie

So you, just from reading the abstract, somehow know that the authors are wrong and that "The results, to a high degree of statistical accuracy, contradict the predictions by any classical or semiclassical theory" somehow supports the classical theories.

And, it seems, when you wrote "I would like to take a look at the experiment setup you were describing with the photon detectors closer", you were just blowing smoke, never had any intention of looking at the experiment setup, and have already made up your mind that you and you alone are smarter than all the physicists put together.

I won't be wasting any more time on you. You are ineducable.

Ways to verify it exist, whether you see them or not.

With a very large number of nodes ~10^10 and an even larger number of interconnections. Only when we have built computer simulations and/or brain mimic hardware on that scale will I consider the possibility that something quantum mechanical is essential to consciousness. I don't expect to wait too long if Moores Law continues to hold.

The scale they have got to so far shows a lot of promise so I think the mechanists are in with a chance here.

DNA works at the molecular level and the people who build custom nucleotide base sequences have got pretty good at synthesising them to order and at high purity. A somewhat worrying prospect in that designer DNA is a two edged sword. As I said the choice of magic numbers in the code may be a fluke but they are suggestive of quantum comparison rules being important to how accurate replication occurs.

That isn't quite right. A single photon can only explore all those paths that are reachable in the time between setting off and arriving at its destination. Anything outside that volume becomes irrelevant when the photon is counted by a detector (or absorbed) its wavefunction necessarily vanishes everywhere else. Its wavefunction is a probability ripple spreading out from the source and then influenced by the environment.

These days the baseline correlator techniques of radio astronomy are just about operable at optical and IR. The technical difficulties of making it work reliably in the optical are immense, but COAST and NOAO both have interferometer based aperture synthesis instruments operating in the IR visible band now. The path compensators are a nightmare at these short wavelengths but the photons still behave the same. An intro to it is at:

Regards, Martin Brown

But if a straight line is the shortest distance between two points, and photons travel at the speed of light... then the only "paths that are reachable in the time between setting off and arriving" is that straight line.

Next time please post a link where you can download the whole paper without paying money.

cheers, Jamie

Is that true? In a double-slit experiment, one slit can be in the straight path from source to detector, and the other slit can be off to the side. A photon taking the short path can be interfered with by the long path. If one times the delay between emission and detection, with just the short-path slit open, we'll measure velocity C. So what happens to the measured velocity when we uncover the other slit? Does the delay increase, such as to approximate the classical phase shift? Or do we just see a bimodal delay distribution, short path and long path for different photons?

I've also read about some interesting experiments where, essentially, fast shutters are opened and closed in various paths during the photon's flight. As I recall, some very strange things happen.

John

Because it is, to the way we think, illogical, so illogical that a lot of people, including Einstein, wouldn't accept it. It requires faith precisely because we see disturbing, counter-intuitive effects whose only explanation is "just accept it."

And since when is adjusting how reality is

Until somebody demonstrates where the universe came from and what is the nature of consciousness, any theory is as good as any other.

Assuming that the mind would not make maximum use of quantum mechanics is underestimating the marvels of evolution. *You* try designing a machine that will play tennis and solve differential equations (simultaneously!) using millisecond logic elements and meters-per-second interconnects.

John

I once had a coworker who showed up one day in his brand new VW Quantum. I asked him, "Do you have to take it to the Quantum mechanics?" and he was like, "Huh?"

Cheers! Rich

That's where change of mind-set will come in. I don't mind admitting that I don't have an intuitive understanding of why things get heavier when they go really fast, either, but I don't think it's illogical.

Why should there be a "where" that the universe came from? Isn't that pushing the question of existence one step further away? Doesn't it mean "universe" wasn't defined broadly enough to start with? As to the nature of consciousness, that's really simple. It's the set of operating conditions that obtain when one is not unconscious. There is a sort of subjective feeling associated with that state, but trying to explain a subjective feeling by vague reference to currently mysterious aspects of science is an empty exercise. Yes, any theory is as good as any other, but none is as good as no theory at all, until what is being explained by the theory can be shown to have an objective existence. Unless it's just too uncomfortable to say "I don't know, and probably never will."

You could say that a present-day computer makes maximum use of Ohm's law, since its operation depends on voltages and currents, but that level is not where the computing action is at. It's in the patterns of operation determined by the programming. Maybe there are specifically identifiable macroscopic quantum effects involved in the operation of mind, but until they're identified, it's premature to explain anything by them. As to the last challenge, as an imperfectly designed organism not too good at either tennis or diffeq, I'll leave that to evolution. It should speed up considerably once the silicon units take over.

Well, here's an explanation - the demonstration, of course, is our (and the rest of the Universe's) existence itself:

Cheers! Rich

No.

No.

No.

Yes.

Well, with the same reasoning, the same thing could be said about electronic design.

robert

Assuming that they are monochromatic photons you get a standing wave established that propogates out away from the equal path length crossing point (white light fringe position) at the speed of light until the photon is absorbed or detected. If you tried to time gate the output to isolate only the short path you would know which slit the photon passed through and so the interference fringes would vanish. I am pretty sure that if the gate was set to anything beyond the path length of the longer path you would see fringes. I don't know if it has been done experimentally.

Discussing this with you has caused me to consider what would happen with ultra fast time gated systems and I have a thought experiment that I think might actually be possible in the lab using Pockel cells to switch a beam for a suitable choice of wavelength with a moderately long coherence length.

My physical intuition is normally pretty good, but I cannot decide what would happen in the following setup:

A laser beam is pointed into the apparatus and a pair of Pockel cells are arranged that are both normally closed and are then opened in a very tight short window (40ns on/off transitions are routine now). The timing of the gates is arranged so that only photons which are momentarily trapped inside the gap width g between the cells can ever reach the detector.

A photon has to have a certain coherence length to have a well defined frequency in E =3D hv. But in this experiment we force the photons to be localised in a space shorter than this length so that according to Heisenbergs uncertainty priciple /\p/\x >=3D h/2pi. Same as sidebands on a short length of pure tone peep.

If the gap is shorter than the photons coherence length they must end up with a more dispersed energy distribution. Their energy distribution with a spectrograph afterwards. If the time gated individual photons do change in energy (as I am sure they must) where do they grab the energy from during their brief spatial confinement? And for extra marks would the results be any different if the Pockel cell shutters were either mirror surface rather than totally absorbing on their inner surfaces.

The really tricky question is what happens when the beam is so dim that only one photon at a time is trapped in the gap. How does it lose or gain energy then? (I presume it is borrowed from the collapsing wavefunction outside the gate but I honestly don't know - and the experiment might at least in principle be doable). I am fairly confident that the uncertainty principle wins here, but I am much less sure how energy is conserved to satisfy /\E/\t >=3D h/pi. I guess it means that it has to eveolve in time and return back to being a photon of energy E fairly quickly after leaving the confining volume.

I'd be interested to hear what folks with a modern QM education think would happen here and why. Or even better has this experiment already been done and what were the results? My own QM knowledge is somewhat dated.

Regards, Martin Brown