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Double-Slit Experiment in Time, Not Space
TheMatt writes "Thomas Young's double-slit experiment is a classic experiment that helped establish the wave-like nature of light. Since then, it has been done with atoms, buckyballs, and biomolecules. It has even been seen in a single molecule, and the single electron version was voted the most beautiful experiment by Physics World readers (covered previously on Slashdot). Now, PhysicsWeb is reporting that Gerhard Paulus and coworkers have conducted the double-slit experiment using a double-slit in time, not space. The "slit" was a crafted femtosecond pulse consisting of one-and-a-half cycles--say, two maxima and one minima--passed through an argon gas. Each maxima has a probability of ionizing an argon atom and producing an electron. The electrons were accelerated to a detector which observed an interference pattern since the detector had no idea which maximum produced the electron."
Just today at lunch I was saying "Wouldn't it be cool to craft a femtosecond pulse consisting of 1.5 cycles, say 2 maxima and 1 minima, passed through argon gas? We could get electrons which could be accelerated then observe the resulting interference patterns!"
Well, that didn't fly. The guys got pissed off and yelled "Shut up and watch the stripper!" so I sheepishly went back to my titties and beer.
Trolling is a art,
New look for classic experiment
2 March 2005
Physicists in Europe and the US have performed a novel version of the double-slit quantum-interference experiment with single electrons. In the classic version of the experiment, electrons pass through a mask containing two parallel slits and produce a pattern of bright and dark interference fringes on a screen. Now, Gerhard Paulus of Texas A&M University and co-workers in Berlin, Munich, Sarajevo and Vienna have observed an interference pattern with electrons that pass through a double slit in time, not space, as a result of being ejected from an atom at one of two possible times by a laser pulse.
The double-slit experiment was first performed with light by Thomas Young over 200 years ago.The formation of the fringes can be explained by the interference of waves travelling from the two slits. When the peaks of the two waves coincide on the screen, the interference is constructive and the result is a bright fringe. However, if the peak of one wave coincides with the trough of the other, destructive interference results in a region of darkness.
The spacing between the fringes depends on the wavelength of the light and the separation of the slits. Similar interference fringes have also been observed with electrons, atoms and molecules, with the fringe spacing depending on the de Broglie wavelength of the particles. Experiments have also shown that an interference pattern builds up even if there is only one particle in the apparatus at any time, and that the pattern disappears if we try to determine which slit it passes through. This process is now understood in terms of interference between the two possible paths through the apparatus, rather than between two waves or particles: if we know "which way" the electron passes through the slits, we do not see interference, and vice versa.
The latest experiment is radically different because the slits exist in time not space, and because the interference pattern appears when the number of electrons at the detector is plotted as a function of their energy rather than their position on a screen. The work was performed at the Technical University of Vienna in collaboration with physicists from the Max Born Institute in Berlin, the Max Planck Institute for Quantum Optics in Munich and the University of Sarajevo.
Paulus and co-workers focused a train of pulses from a Ti:sapphire laser into a chamber containing a gas of argon atoms. The pulses were so short - just 5 femtoseconds - that each one contained just a few cycles of the electric field.
The team was able to control the output of the laser so that all the pulses were identical. The researchers could, for example, ensure that each pulse contained two maxima of the electric field (thatis, two peaks with large positive values) and one minimum (a peak with a large negative value). There was a small probability that an atom would be ionized by one or other of the maxima, which therefore played the role of the slits, with the resulting electron being accelerated towards a detector. If the atom was ionized by the minimum, the electron travelled in the opposite direction towards a second detector.
The team registered the arrival times of the electrons at both detectors and then plotted the number of electrons as a function of energy. The researchers observed interference fringes at the first detector because it was impossible to know if an electron counted by the detector was produced during the first or second maximum.
There was no interference pattern at the second detector because all the electrons were produced at the same time at the minimum. However,when the phase of the laser was changed so that there was one maximum and two minima, interference fringes were seen at the second detector but not at the first. "We have complete which-way information and no which-way information at the same time for the same electron," says Paulus. "It just depends on the direction from which
Be better in bed. Wikiafterdark!
I know I'm probably going to be rated down for not being all-knowing, but could someone try to explain this in a bit more simplific terms? I know what the dual-slit experiment was, but I don't understand the purpose of this particular one.
I've been trying for years to do the double-slit experiment. Alas, the wife still won't go for it.
to divide the your two slits in time AND space so they don't get a grip of each other and get very angry and slap you in the face before leaving.
But my wife and my girlfriend started fighting each other.
Uh...What he said.
Any phycisits out there who are bored who wouldn't mind explaining this to the rest of us?
Be better in bed. Wikiafterdark!
"Adressen på den hjemmeside, du ønsker at finde, er enten forkert, eller også eksisterer hjemmesiden ikke længere. Du kan prøve følgende:
Tjekke om adressen er stavet rigtigt. Bemærk at det har betydning, om du bruger store eller små bogstaver!"
that may as well have been the writeup, because i don't understand a word of it.
Did Michael Simms kill himself after being canned by Taco?
Has Michael blogged about Taco being a corporate fascist yet?
Huhu....you said slit
I just glanced at the calendar. Nope, not April Fools. So why exactly is a large paragraph of nearly incomprehensible text on the front page of Slashdot?
I didn't know your mom would ever make the slashdot front page!
Do you guys get aspirine with your subscription? Cuz if you do, I'm signing up right now...
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
I think I hurt my brain just trying to figure out this /. post.
Wasn't trying to Karma whore, just trying to help. I have excellent Karma already, this won't make a difference.
Be better in bed. Wikiafterdark!
Heh, I was just writing a school project on Quantum Mechanics, and then this comes up. I'm about to go to sleep and just cannot be bothered to read it atm!
a) That's the default picture for articles in the "Science" category
b) Albert Einstein made fundamental contributions to quantum mechanics
Not to mention flowers, too...
Obliteracy: Words with explosions
Buy Steampunk Clothing Online!
"Maximum" is singular. "Maxima" is plural. Minima are similar.
So it's "two maxima and one minimum."
I believe posters are recognized by their sig. So I made one.
if ( yuo == tehRetard ) {
dont.post();
}
For those of you who are unfamiliar with the double-slit experiment, there is a very clear, non-technical explanation here.
This space for rent.
It's funny how one of the linked articles refers back to this site they way this site refers to it. It's like when you have a mirror and you face it towards another mirror...
...only, Slashdot has never been "physicswebbed"...
I might know what I'm talkin' about, but then again, this is Slashdot...
Ok. I admit it, I didn't understand more than 5 words there, and I loved every second of it!
It's The Golden Rule: "He who has the gold makes the rules."
So are they implying that time is a wave?
That being the case, wouldn't that also imply that time is decoupled from space? IE - there is no space-time?
It would seem that you can't measure time without measuring space. Of course, I'm not a physicist and I don't pretend to know what I'm talking about. So I'm sure I'm totally off base and misinterpreting the entire thing, I don't need to be told that in a vicious fasion, thank you. Please drive through.
...that this has to be the most confusing summary ever. Here's my guess on timothy's brain processes.
... wave-like ... femtosecond ... maxima ... minima ... interference pattern ... Oooo shiny (click's approve).
;-)
double-slit
Or am I the only one who knows absolutely nothing about this subject or the significance of the experiment?
How about some *editing* timothy?
cLive
-- Trinity in high heels carrying a whip: The donimatrix - there is no spoonerism
Mod parent up! Mod this post funny
What again?
Well, ya got to start somewhere.
The simple truth is that interstellar distances will not fit into the human imagination
- Douglas Adams
My god, it's full of rainbows.
Shahriar Afshar's 2004 double slit experiment pretty much invalidates a common belief in Quantum Mechanics, namely Bohr's duality principle. In his experiment, photons behave as waves and particles at the same time.
The Raven
I don't see how this involves new theoretical physics. I'm pretty sure the thought experiment was performed and calculated some long time ago. The only thing new is actually performing it.
Relativistic time dilation has been demonstrated by synchronizing atomic clocks and sending one of them into space for a while at high speed. The one sent into space slows down a tiny bit. As I interpret this, one of the clocks is slightly in the past relative to the other one.
Suppose you did the same thing with two entangled particles. The particle sent into orbit be slightly in the past relative to the other one. So would they then be entangled across the dimension of time? Seems like this has big implications, though what they are is beyond me.
The very thought of making 5-femtosecond laser pulses (0.000 000 000 000 005 sec, right?) leaves me feeling dumb and slow.
That aside, someone please clue me in here:
So if the electrons hit the laser when the pulse was at maximum strength they would hit the detector, like the two "beams" of light passed through the slits in Young's experiment? and the ones that pass "between" the maxima and minima get distorted like the blurry edges of the light? thus making "slits" of electrons but at instants in time instead of separate points? (I'm no physics expert but I'm sure you guessed that by now...)
You can hold down the "B" button for continuous firing.
Im going to need alot of pot to understand this one.
The Code Ninja is swift with his tool, precise in his delivery, and deadly accurate in his execution.
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I can understand the use of a Maxima, it's a solid car. But pairing it with a Minima (I think it's Kia's Minivan model, not sure) is just silly.
There are 01 kinds of cars in the world. The General Lee, and everything else.
Come one, that's not even trying!
if ( yuo.isRetard() ) {
yuo.setAllowedToPost(false);
}
You gotta find first gear in your giant robot car
verbatim quote, I kid you not:
is the interference of single electrons in a Young's double slit.
Yeah, 'interference'... Young's double 'slit'.... where do I sign up? Some of the curves on the graph were not work safe!
Is this porn for those who never see the light of day?
#hostfile 0.0.0.0 primidi.com 0.0.0.0 www.primidi.com 0.0.0.0 radio.weblogs.com
Rough trans: The address of the homepage you wish to find is not here or doesn't exist any longer. You can try the following: Check if the address is spelled correctly. Notice that it has meaning if you use capital or lowercase letters!
Or maybe it says something about a moose.
I thought the meaning of the double slit test was to prove that the single electron actually passed through both slits, and in essence interfered with itself.
But in this case we're dealing with two different electrons fired at different times, so it's not quite the same.
Even so, if the electrons create the interference pattern, that means they must have collided... in time? So the second electron reached the point of collision before it was actually fired.
Does that mean that every electron travels every possible path in space AND in time? So whenever it is possible for an electron to be fired, it does, and interferes with all other electrons fired at all other times?
My head hurts. Damn you, Science.
"Reactionaries must be deprived of the right to voice their opinions; only the people have that right." - Mao
Did they find out the result before they did the experiment?
There's gotta be a Bill & Ted quote in there somewhere.
--- This
This is nothing compared to the Unification of Electromagnetic and Gravitational theories. It has been done and the results can be found here.
Or so I've been told. The book explaining the theory is ~$26USD.
"Rocky Rococo, at your cervix!"
I've been doing my own double-slit experiment, with web pages.
On one side of my screen is slashdot. On the other is the Devil Chicks From The Fourth Dimension web site.
Devil chicks, physics, devil chicks, physics
Looks to be that they have redone the classic double-slit experiment in a new variation.
Instead of having the two slits existing at the same time but in different 3d space, they made the slits in different time, but in same 3d space.
Probably we have the same quantum effect as in the traditional double-slit experiment: When trying to determine which slit the particle passes through the interference pattern goes away, as the waves change change to particles.
It doesn't look to me like they have seen that experimentally yet. Their setup that did not produce the interference pattern looks more like a single-slit to me.
But I think that an attempt to find out at which of the two maxima are ionizing an argon atom should make the interference pattern go away.
How does it invalidate Bohr's duality principle?
And what was the limitation or flaw in Bohr's reasoning, that he didn't figure this out for himself when first formulating the duality principle?
Also, how did Afshar overcome this limitation, or correct this flaw?
Finally, does this new discovery change the face of physics in any meaningful way?
Any sufficiently well-organized community is indistinguishable from Government.
Excuse me?!?
Einstein won the Nobel Prize for explaining the photoelectric effect, which basically kicked off the whole study of quantum mechanics on its own. Too, he solved equations for the gas circulation in a radiometer, and got into the famous EPR "paradox" and debates with Bohr. If you think he only worked on gravity, you're sorely mistaken.
I'd love to see a geometric illustration of how this demonstration is identical to Young's, rotated in spacetime.
--
make install -not war
IANAP, But by the looks of it, they're firing a pulsating laser into a chamber of gas. The laser has a chance to get ionized (positively or negatively, they couldn't tell) from the gas and go flying towards a detector. This created a pattern and they mapped a funtion out of it. Now I could be wrong, so if someone has a better explaination please share.
Basically, you can look at light, or electrons, or whatever, as either a particle or a wave. Sometimes one interpretation will work better (light as a particle explains the photoelectric effect, light as a wave explains interference patterns, diffraction, etc). Current state of play is that the wave interpretation is always the best way to look at things, except when you observe the system everything collapses to particles, and when something mathematically inconvenient happens (you can explain the photoelectric effect in terms of waves, but the maths is horrible).
Classic two slit experiment with light consists of shining laser light on a barrier with two slits; each slit produces a diffraction pattern (http://en.wikipedia.org/wiki/Diffraction), the diffraction patterns interfere to produce the classic two slit pattern, see same link. This basically works because the laser light is coherent, you can (sort of) treat all the photons coming from the laser like one photon.
If you do this with electrons, because electrons are waves, you get the same patterns. Ditto any other particle.
Even if you do this experiment firing only one electron at a time you will get the same two-slit interference pattern, although 'common sense' tells you the electron can only pass through one of the two slits what actually happens is it passes through both at once. If on the other hand you fit a detector over one slit to register the passage of electrons, so you can tell which slit the electron passes through, you lose the interference pattern, you get two overlapping single slit diffraction patterns, which is not the same thing.
Roughly, if you have two slits and whenever an electron is fired at the slits you do not know which slit it went through, but the classical probability (what you'd expect if you didn't know quantum mechanics) of either slit is 0.5, then you will get a two-slit pattern.
This is basically the same experiment, except instead of two slits in space a little distance apart there are two possible source times for the electron, separated by a small time gap. There is no way to know whether a detected electron was produced at the first or second time, so the maths works out (roughly) the same as for the two slits in space case and you would expect to see the classic two-slits pattern. But it is kind of neat that someone's actually found a way to test that idea.
Sounds (as much as this layman can determine) quite a lot like the process used in Michael Crichton's novel Timeline.
...how can we turn this into some sort of weapon?
Proverbs 21:19
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I thought the plot of the new show would be a lot more interesting than this one.
As a nuclear physicist, I don't see much of a point in posting a article like this. Regardless of what people may believe they understand from this article, the article is for people who speak the language only. It's also vague, abstract, and very general in comments, but in a way any physicist can get the general idea. In other words, this link isn't for the slashdot audience. Next time I'd wait for a more pedestrian article.
So, if this occurs in time AND space -what the heck does that say? (I "ain't" no physicist nuther, soes bear with me (sic)) Is the concept: Combinations of space and time can cause creative or destructive interference? A simple equation involving complex variables, rational analysis, and non-Euclidean geometries will suffice here - no seriously is that what they are saying about interference patterns?
Bob did it first...
I don't care if it's 90,000 hectares. That lake was not my doing.
We already knew that particles are also waves... What does this experiment show us that's new? Does it show that two particles are a wave, or something?
Comment removed based on user account deletion
**Skip the first part if you know the basics.
If you pass a water wave through a wall with two slits in it, you will get interference. If you put another solid wall (no slits) beyond and parallel to the first wall, you will see that the water line on the 2nd wall looks like a sinewave with magnitude tapering off as you get further from the slits.
If you pass particles (electrons, photons, etc) at a wall with two slits, and place a "detecting wall" beyond the first wall, then the distribution of electrons hitting the detecting wall would be similar to the wave observed against the 2nd wall in the water example.
--New Experiment--
In the new example, two pulses of light can trigger an electron to be released. Think of these two pulses as pulling a trigger on a gun while playing russian roulette. The electron is the bullet and the detector is your head. If you pulled the trigger at 0 secs and 2 secs, you'd expect to see a person die at 0.01 seconds and/or/neither 2.01 seconds, assuming it took 0.01 seconds for the bullet to reach the person and kill him.
The detector, however sees an interference pattern. This is like seeing deaths at 1 second or 1.5 seconds. The interference pattern is measured as a function of time, and instead of seeing two blips in time, they saw a range.
Yes and no. And you can reference this paper to prove it.
First there was Chinese relativity
"All of your problems, no matter how big or small, 1.2 billion chinese people could give a fuck"
and then there was relative relativity
"No matter what your achievements, your aunt will continue to tell your girlfriend/wife about the time when you ran nude in the garden aged 5"
and now I bring you the Scientific relativity theory
"No matter how smart you think you are, you still look smart to a time splitting physicist"
An Eye for an Eye will make the whole world blind - Gandhi
First: I have not read your whole message, because I'm a bit busy. But your assertion that people who don't think about the minus sign in front of the time-term in the spacetime metric is vapid, since if it's not there, it has to be in front of each of the space terms. There's no real significance to where you place it (just as there's no real significance as to what sign you choose for the Laplacian for a potential). The important thing is that *either* the time term be negated, *XOR* the space terms be negated in the spacetime interval.
Second: The word "dimension" means simply that there is some parameter with which we can measure some aspect of a system, and which is independent in some sense from the other parameters. To convince me that the "time dimension" is somehow "moving" relative to the "space dimensions", you need to tell me what ticks I can detect on the "time dimension" which will register as they flow by. Otherwise, that axis may move, or not, arbitrarily, and I'll have no clue about it (and thus it doesn't matter one way or the other). After all, a perfectly smooth, infinitely long ruler does me absolutely no good. It needs some invariants on it that I can measure against.
There is no "wave-like nature of light".
A photon has a property in complex space that when combined with another photon results in a pattern of intensity in real space similar to that produced by combined waves, but itself has no more "wavelike nature" than the Coca-Cola dynamic wave device" trademark does.
This rant is directed at the moderators not the parent. I realise that most people on this site do not understand quantum mechanics, and that is fine - I don't expect everyone to be an expert in everything. I am even willing to overlook the jock-like "ignorace is cool" toned jokes. However, the fact that ignorance is constantly moderated Insightful on slashdot is really getting on my nerves.
A post like this that simply states that the poster doesn't understand the story, or posts that ask questions about the story are not insightful. They often do have a place in the conversation. And if many people have the same questions, or misunderstanding, it is good for them for them to be moderated up, so others can see the question (and hopefully some good responces). But moderate it Interesting or Underated, not Insightful!
Even for my own posts, I think that most of the Insightful moderation I have recieved should have been Interesting or Informative. Or maybe we should give up and just change the Insightful mod to "Hell Yeah" since that is how everyone seems to use it.
> So are they implying that time is a wave?
;-)
No.
In the original double-slit experiment, waves were made to interfere by passing through two slits, to form a diffraction pattern.
This experiment is similar to that which every first year physicist does, except that instead of aiming a laser through two holes, it is being aimed at an atom. The two emitters of coherent waves (previously laser light through two slits), are now created by causing a single argon atom to emit an electron (wave particle duality and all that), at two points in time - hence the two maxima being fired at it.
It's a tiny bit more complicated than that, because the interference pattern doesn't show up over space, but by this point, you may as well read the IoP page.
Experimentally it's very good. In terms of theory, the results would have been predicted by anyone with a knowledge of quantum physics for the last 80 years. So nothing universe-shattering about it.
I hope that wasn't vicious, and... IAAP.
I think I like this description the best, outside of the article itself. Mod parent up, anyone?
So what are the winning lottery numbers for tomorrow?
In the traditional double slit experiment. We see interference if the particle may have past between one slit or the other. And we have no way of telling which.
This creates interference between the two (possible?) waveforms the photon (may) have taken.
In this case. The two paths are.
1.) The photon was created by the first maxima
2.) The photon was created by the second maxima.
I'm not sure why which maxima created the particle is indeterminate. (Maybe because it happens too fast compared to the photons frequency.)
But the interference pattern generated is interference between those two possibilities.
Ie I believe it's being suggested that the two possible waveforms of the two events are interfering across a small gap in time.
How do they know that the interference pattern is created by electrons being fired at different times rather than from different locations? If you're firing two laser pulses into a random cloud of argon atoms, wouldn't you expect the pulses to hit electrons in different locations?
"Dr. Elliot's treating this as an open-source physics project"
In other words he's treating it as a physics project.
To demonstrate this, find a sink with two distinct taps. Half-fill the sink with water. Now, turn the taps so that the water drips out slowly from each. You will see ripples spreading out from where the drops strike the water. You'll also see that where the ripples cross, there are light patches, dark patches and some areas that seem to be smooth.
The light and dark patches are where you have constructive interference. If you have a trough, then the trough is deeper than normal and hence appears dark. If you have a peak, the peak is higher than normal and appears light.
the "double slit" experiment was devised by your typical mad scientist. The idea is simple enough. You direct a stream of photons at one of two very narrow gaps. You then have some sort of screen on the other side for the light to shine on. If photons are just particles, then they will go through that one gap and show up as a single spot on the other side.
If, however, particles are waves, they will go through BOTH gaps. The waves will then interfere with each other, as in the sink experiment above, and you'll see patches of light and dark on the other side.
What you get is patches of light and dark, showing that light behaves like a wave.
Now it gets really fun. Turn down the light source. If light is a wave, you expect the same interference pattern, only dimmer. Err, no. What happens is that you start getting a speckled pattern. Eventually, the bands dissolve entirely and you just get a single spot. This proves that light is a particle.
There are a number of ways to resolve this apparent paradox. The simplest is to say that light is a particle that can exist anywhere in the wave with a given probability. With enough particles of light, you see a complete wave, because every possible part of the wave is occupied. With insufficient particles, you get an incomplete wave, and therefore the incomplete interference pattern that you observe.
Now we've got the spacial part over with, we move onto time.
The experiment demonstrates several things. Firstly, it demonstrates that time behaves in a similar manner to space, with regards to objects travelling through it. This will really irritate physicists who have argued that although time and space are coupled, as per Einstein's space/time model, time was not a dimension in the sense that spacial dimensions were. That's going to be a much harder line of reasoning to maintain, now, because clearly time DOES behave in the same way as a spacial dimension, when it comes to diffraction.
The second - and more important - thing that is shown here is that objects do not just have a probability of existing in a specific point in space, they ALSO have a probability of existing in a specific point in time.
Other than causing Professor Hawking a whole bunch of headaches, I don't see this new observation as doing a whole lot. There may be a way to exploit the technique to generate an animated hologram, though, as you'd have a way of influencing interference patterns with respect to time from a single image, but that's about it.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
If you want to swallow mathematically unjustified drivel, I highly reccomend Gene Ray and Time Cube. I think Mr. Ray is at the pinnacle of meaningless drivel, and your paltry example doesn't even come close.
Alternatively you could actually do the math - Here's a nice textbook you can start with, or just search Amazon for "differential geometry".
Jedidiah.
Craft Beer Programming T-shirts
http://prola.aps.org/abstract/PR/v88/i3/p625_1
The electrons were accelerated to a detector which observed an interference pattern since the detector had no idea which maximum produced the electron.
I, for one, welcome our new sentient interference pattern detector overlords.
It's too bad more laypeople don't get into quantum physics, string theory, etc. The implicatisons are pretty amazing on both scientific and spiritual levels, and I have chosen to read much of what this science tells us as: The Universe (Multiverse) is One and Many simultaneously, we are all a part of it, and in essence, are all One. Time is an illusion on the ultimate level, as is the notion of our matter and energy being separate from every other element of the universe. Thus, death as we know it does not truly exist, when what you are is a focal point of the neverending Multiverse (God, if you wanna put it that way -- but that's up to you).
Gee... I wonder why they don't teach any of this stuff in the school system, unless you happen to go into phsyics?
I highly recommend The Tao of Physics by Capra (which I'm sure many scientists loathe). Also writings by Nick Herbert are pretty interesting. A lot of the stuff we are finding equations for now is what many indegenous cultures have taught for thousands and thousands of years. They may have communicated the ideas differently, but they strike me as having the same message.
---
The techno-mediated cultural conspiracy
http://thewired.blogs.com/teotwawki/
Just a randomly picked response to this thread.
Here ya go:
www.timecube.com
There's gotta be a second or fourth corollary to Goodwin's Law here somewhere... mentioning the time cube guy....
You'll be much better off posting in a forum where people don't actually know any real math or physics beyond what they read in Scientific American. Anyone who actually has a clue can see this for the drivel it is just from your abuse of semantics alone.
Jedidiah.
Craft Beer Programming T-shirts
The "slit" was a crafted femtosecond pulse consisting of one-and-a-half cycles--say, two maxima and one minima--passed through an argon gas.
Anyone who has a femtosecond pulse generator should feel comfortable with this. If not, get access to a two-photon UV femtosecond pulse generator which uses nanosecond-time-scale infrared laser to deplete the terminal state of an F2 laser, based on F2 transitions.
Next, you'll want a healthy dose of argon gas. Argon is used to reduce heat loss in sealed units by slowing down convection inside the air space. You can get argon gas cartridges to prevent wine oxidation, which is a neat little side benefit. A 50L cylinder filled with argon gas to a pressure of 10130 kPa at 30C has approximately 201 moles of argon. Just remember that if you're going to lase with argon, its most efficient transitions are at 488 nm and 514.5 nm.
So now you'll need to create an ion chamber using the argon gas. You'll need a metal conducting can, and a wire electrode in the center which is well insulated from the chamber walls. The chamber, of course, will be filled with argon.
Next, you'll need to use your femtosecond pulse generator to apply a DC voltage between the outer can and center electrode. This will create an electric field, of only a few volts, that sweeps the ions to the oppositely charged electrodes. For some additional fun, if you apply a few hundred volts, the electron emissions will produce "secondary emissions", which amplify the results. I wouldn't recommend creating one of these by hand if you haven't already done so, but remember to use a 4.7uF capacitor with non-polar film, a 100,000 megohm resistor and a 2N4117A electrometer-grade JFET.
Anyways, generating a local maxima shouldn't be too difficult if you keep the phase dynamics of your pulse generator within one half delta of the wavelength propogation delay of your argon gas cylinder. This, as always, varies according to room temperature, so be sure to calibrate your scales before attempting the experiment.
The trickiest part of the experiment is to build a ray tube to display your intereference pattern. I suggest using a Tektronix Type 453 Oscilloscope, which may be hard to find but has the best bang per buck.
In no time at all, you'll be generating double slits in time!
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Re: the top physics experiments
I didn't do much physics at school. Is there a good book (or other single source) that tells me how I can recreate the experiments, maybe with some history and comment on the significance of the experiment?
Planck's constant has dimension equal to what is called 'action'. This is energy times time. It also works out to be equal to position times momentum, etc. This means that there is some inherent uncertainty in a measurement of when something happened, unless you don't measure its energy at all.
It's funny how one of the linked articles refers back to this site they way this site refers to it. It's like when you have a mirror and you face it towards another mirror /.-crowd.
So this builds a resonator. We might get a coherent unidirectional high-energy slashdot beam out of this! We only need to get a poplation inversion in the media, like more people in the higher states....
Damn, wont happen with the
Or maybe we can excite them:
Look there! Natalie Portman naked, petrified and in hot grits! And she is running linux!
Comment removed based on user account deletion
...Young's double-slit experiment is a classic ... done with ... buckyballs...
I don't know much about this stuff, but I sure wish my name was "Bucky" about now!
as opposed to an interference behavior?
Essentially, the experiment showed that if the photons released in the argon gas are triggered by a wave with only a slope on one side of the wave that you get an "Interference Pattern". And that if you do this from the top of the wave the interference pattern shows up in one direction and if at the bottom of the wave in the other direction.
Assuming they know this for sure (and they don't!, we cannot *see* light waves, only observe effects and speculate as to cause), why is this not a behavior of photons being created by incomplete waves (IE a left half or right half wave)? Which seems more likely than a spooky time based interference?
Does the emperor have clothes here? Where did I leave my Occams Razor?
... instead of Journalism. My brain hurts.
The experiment depends on the fact that we have no idea which slit any particular particle passes through.
False, the fact that we have or not an idea is simply irrelevant to the result, is the kind of detector what makes up the difference, quantum is not about 'we' is about 'it'.
Does it run linux?
The man who trades freedom for security does not deserve nor will he ever receive either. - Benjamin Franklin
Interesting :) God is metric tensor. I would never have thought of that myself.
Jedidiah.
Craft Beer Programming T-shirts
It sounds to me like you've been reading labels from Dr. Bronner's soap. ("WE'RE ONE! ALL-ONE! EXCEPTIONS ETERNALLY? ABSOLUTELY NONE!")
---------The early bird gets the worm, but the second mouse gets the cheese.
How many people read the whole thing, researched it, and modded it overrated?
I could have told them that would happen. Really, like the whole thought that the detector would be able to tell which maxima hit the argon thingy is totally absurd. Like, duh. Um, yeah. *quickly googles femptosecond, maxima, minima...egads...*
Insert witty comment *here*. I'm fresh out of wit...
http://ieeexplore.ieee.org/search/wrapper.jsp?a
Ionization of the argon atoms apparently imparts a phase shift to the ionizing pulse. Therefore, the argon gas acts as a dispersive medium.
Farhad and Hosain Hakimi demonstrated the same idea using short optical pulses in dispersive optical fibers. The fiber acts as a lens, generating the "far field" response -- i.e., the Fourier transform. They also demonstrated a practical use for their temporal gratings -- continuously-variable true time delay of optical pulses.
Among the useful applications of true time delay is optical logic and phased-array radar.
Agreed. Anyone remember Dr. Timecube (Gene Ray)? His theory is that:
(a) he is the wisest man in the world
(b) anyone who doesn't believe him is evil (belief would require understanding, which in and of itself is a challenging goal... try reading his website sometime http://www.timecube.com/)
(c) logical inconsistenscies are perfectly acceptable, so long as he is the proponent (after all, he _is_ the wisest man in the world).
Thanks for the feedback.
Dr. Elliot's theory of moving dimenstions stands unrefuted.
He's working on the final paper, and feedback utilizing logic and reason would be very useful.
The only way to stay still in the three spatial dimensions is to move at the velocity of light c through time. The only way to stay still in the time dimension is to move at the velocity of light c through space. How else can this be explained, but with space and time coordinates moving relative to one-another, with the time dimsion expanding as a spherically symmetric wavefront?
It would be great if the detractors could use logic and reason in refuting Dr. E's theory, rather than just refuting it by dismissing it.
What doesn't make sense in his theory?
If you think he's going wrong, where is he going wrong?
The time dimension is moving relative to the spatial dimensions.
...your head asplode
Will this be on the final?
First of all, if you don't know the classic double-slit experiment, read Double-slit experiment at Wikipedia. In the classic experiment, we send something (a photon, an election, whatever) through two slits, and plot the number (of photons, electrons, whatever) vs. the position. Now due to the uncertainty principle we know that Delta x*Delta p>=h-bar/2, where Delta x is the uncertainty of position, Delta p is the uncertainty of momentum, and h-bar is a constant (see Planck's constant for more info). So we can derive the formula lambda/s=x/D, where lambda is the wavelength (of the photon, or the de Broglie wavelength of the electron), s is the slit separation, x is the fringe width, and D is the distance of the slits from the screen.
Now in this new experiment, we send a photon which has a wave consisting of two maxima and one minimum into a cloud of atoms. An electron may be emitted from the cloud and sent to the screen, and we measure the time it arrives at the screen. This electron could have been emitted from the first maxima or the second maxima (ignore the minimum as those electrons get sent to the other screen). If we plot the number of electrons vs time, we should see the exact same interference pattern as with the plot of number of electrons vs. position that we see in the classic experiment. And the uncertainty principle can also be expressed as Delta E*Delta T>=h-bar/2, where Delta T is uncertainty of energy and Delta T is uncertainty of time. So now we should find that E/s~x/D (I'm not sure if this is right, and not sure if I'm missing some constants so I used proportional rather than equal here). E is the energy of the photon, s is now the difference in time between the two maxima, x is still the fringe width (though it's now measure in units of time), and D is still the distance between the screen and the (in this case cloud), but I suppose you have to measure the distance in time (the time it takes the electron to travel that distance).
Anyway, this is all a guess, since the actual experiment doesn't seem to be found. If someone sees a glaring problem, feel free to flame.
Is this porn for those who never see the light of day?
It's porn for those who see the light of day as both a particle and a wave.
Colin:
For the last time, System Restore and NTBackup are different programs for different purposes. Telling people that System Restore is junk and they should only use NTBackup is a disservice to the Win XP community.
Oh, wait, that's the other redundant and repetitive poster I saw today. Sorry.
I figure by 2030 or so my 6-digit UID will be something to brag about.
Relativistic time dilation has always seemed incredibly counter-intuitive to me.
It seems very easy to me to come up with two bodies moving in such a way as to make it impossible to determine which one is moving faster, because the answer to that question depends completely on the point of reference in relation to which you determine their veolocity.
Which means that there's no way of determining which of the two bodies will age more quickly and at what rate they will age in relation to each other - according to the exaplanations I've been given, there are infinitely many answers to that question. But the point of reference you use is merely a mathematical abstraction and, being immaterial, has absolutely no impact on the real world. It would seem that the implication is that I can change the way every body in the universe is behaving just by thinking about the universe in slightly different way.
I know this is impossible, so I just want to ask, what the heck is the missing piece? Is the explanation an oversimplification, or am I completely misinterpreting it?
Yup, I have no idea what that guy is talking about. Anyone who is unable to communicate coherently ought to expect a high degree of skepticism.
You're absolutely correct: your perception of how the two bodies are moving, and how time appears to pass, is dependent on your relative velocity to them. In other words, the observer constitutes a third object in your two-object system. That's the point of 'relativity': your reality changes with your relative motion. And with gravitational fields, etc., etc.
As I have already requested (in a different reply to a different on of your almost entirely redundant posts) a full proof for me to dismantle, I will keep my response to a few key problems (see: fatal flaws) I see in this postulate.
(A) How do you propose to measure velocity using only measurements of the time dimension? Last I checked, velocity is defined as (spatial units translated)/(temporal units translated).
(B) If we simply look at this in two dimensions, restraining spatial coordinates to the x direction, and our second dimension being time, your theory would have the origin of the t axis sliding up and down, while the x axis remains stationary. While this will change the appearance of our visual rendering of the coordinate system (for example, we may draw the x axis intersecting the t axis at t=-4s, for instance), it is simply smoke and mirrors. An event at (t1,6) will always be 4m away from an event at (t1,10). An event at (t2,-5) will always be |t2-t3| away from (t3,-5), no matter how much you shift the numerical origin of your t axis. My point is this: any coordinate system is relative to an arbitrarily chosen origin. While you may renumber your t axis as often as you wish, and thus have it "slide" to and fro relative to your other axes, the relative spacetime differences between events will remain the same.
(C) Sorry, ran a bit long on (B), so i'll make this my last point. This point is one of semantics. You state that the time dimension expands as a spherically symmetric wavefront through space. Thus, you feel the time dimension has spatial components. Therefore, your time "dimension" is not a dimension at all, as it contains an x, y, and z component, each which have a _set_ relationship to one another (they define a sphere, as you explicitly state above). For time to be its own dimension, it must be possible for any relationship of x, y, and z to exist at any point t. Perhaps you stated this in a way you did not intend, or perhaps you simply can't wrap your head around four dimensions.
In any case, please either correct any mistakes or misinterpretations I have made, or shelf your theory until you can make the math work.
In English, both "minimums" and "minima" are acceptable.
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
(er. um, we now return you to your regular programming).
Sometimes boldness is in fashion. Sometimes only the brave will be bold.
With an antennas the size and lenght is base off of wave size. If the size is right the antennas get twice the amount of gain. Also the directors and reflector need to be base off of wave size.
Does this help.....
This sounds like a nice, clean experiment. However, wasn't this effect first reported 50 years ago in photon antibunching and the Hanbury-Brown Twiss effects? These are some of the most subtle and beautiful effects in modern physics.
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"crackpots have been coming up with stuff like this for decades" Uh oh. Uncle Al discovered /.
Between the arrival of the first and second maximum, the atom in the gas will be in a different position (distance determined by the temperature of the gas). If the distance is small enough, the atom may well absorb *both* maxima, and emit them (or emit only one). Either way the stream of emissions will not be coming from the same location in space. Wouldn't this be a cause of the interference pattern observed?
I had the same question as you, and a friend attempted to explain the difference to me. Thinking about the twins paradox, I believe the distinction is that the travelling twin changes his frame of reference by accelerating (converting kinetic energy from some other source) whereas the stay-at-home twin stays in the same frame of reference. (Realistically the stay-at-home twin won't stay entirely static, but will use relatively little kinetic energy for sub-orbital travel.) I'm not sure that I understand this correctly though.
The very most simplified layman's explanation of the seeming paradoxes involved in quantum physics resembles existing cultural paradoxes, yes.
That's because those cultural paradoxes already existed. We use our fund of ideas in explaining the new things we find.
You'll note that when an ancient and exotic story from some culture you haven't known much about resembles a new piece of physics, you say "indigenous cultures have taught this for thousands of years," as if they had some good reason to be right. As if they'd intuited the physics, and encoded it in their culture.
But when Lewis Carroll's work is used to explain relativity, do you suppose that Carrol had intuited General Relativity and chose to write a bok instead of a scientific paper? When a line from Hamlet is used to explain part of quantum physics, do you suppose Shakespeare had intuited Quantum Physics?
Hardly. You have an individual Western author there. You can't imagine that Shakespeare had divined the shape of physics intuitively, but been ignored by Western culture. It's too present. It lacks the feeling of magic.
Physicists just use ideas that laymen already have to explain to them the world of physics. When you go into the details of the physics, you find the old aboriginal story doesn't match. Aboriginal dreamtime is one thing, but it doesn't help you to know how many types of quarks there are a priori. A posteriori, having found the number, you can find a myth that echoes it.
For any configuration of physics, whatever happened to be true, there would be some myth, somewhere, which matched that configuration well enough for a human being to accept it as having been a presentiment. There are hundreds of thousands of myths available.
This is the unique power of the human brain... interpreting the new using existing concepts as representations. It's very important to understand that doesn't mean the old representations were of the new, any more than seeing a face in the clouds says that clouds are made to be shaped like faces, or that faces were derived from clouds.
I have seen pictures of the double slit experiment in action, but have never had an opportunity to play with it myself.
So you have two slits, and slight goes through both slits and creates an interference pattern on the far plane.
So the experiment looks like this:
- - -
-----
But what happens if you set up the box so that there is a divider between the slits, like so?
- - -
|
-----
Pretend that line extends to both planes to form a solid barrier.
So what would happen in this case? If you fire one photon at the two slits, would it choose one side only? And why would the fact that there is a barrier on the other side of the plane with the slits affect how light passes through the slits which it arrives at before it knows that the barrier exists?
And what happens if you change that divider in the middle to make it so it doesn't extend all the way to the side with the slits? If you keep making it shorter and shorter towards the side the light is being projected onto, at what point does the experiment return to the way it is expected to behave, assuming it has not been behaving as expected up until this point?
What doesn't make sense in his theory?
Well, the fundamental misuse (or possibly just misunderstanding) of basic terms is kind of a give away. Dimensions don't move, and you can't rotate in 1 dimension, unless you completely redefine what you mean by dimension (i.e. you use it in a sense entirely disimilar to every other mathematician and physicist with any education in the subject area). These are well defined terms (mathematics is a very precise language wherever possible), so misuse is a bad sign to start. The fact that the required redefintion of dimension would render invalid whole swathes of mathematics required to support the theories upon which this stuff is based... well that just kind of makes it all patently stupid.
There's nothing wrong with new ideas, but basing them on existing ideas that you/Dr. Elliot has apparently failed to properly understand is probably not a good way to go about it.
Jedidiah.
Craft Beer Programming T-shirts
Dr. Rocco Siffredi did a 2-slit experiment in Rocco's Physic's Wh0res 6. It established the waif-like nature of...
"As for the future, your task is not to foresee it, but to enable it." - Antoine de Saint-Exupery
In fact you could reduce the complaints to:
(1) The fundamental principle of special and general relativity (upon which this theory is clearly based) is that spacetime is coordinate system independent, and hence any concept of "moving dimensions" is complete nonsense. Either you scrap general relativity, or you scrap moving dimensions... hmm, I know which I'd pick.
Jedidiah.
Craft Beer Programming T-shirts
Isn't there something meaningful in this observation?
Why would energy change with time? Or is it just that the frequency of electron hits adding an negating are causing the variances in energy?
I'd like to stare at the experiment and the graph... Maybe after burning it into my retinas for a while, then sleeping restlessly, then waking and going to work tomorrow, then forgetting about it for a while, maybe then the understanding will come...
My cats breath smells like cats food
"Physics is cool and all, if you're not quite bright enough to make it in Math" "Physics is to math as sex is to masturbation." -R. Feynman
Interesting :) God has exceeded his 40 meg limit. I would never have thought of that myself.
You're absolutely wrong. The other answer is correct. In order to leave, turn around, and return, the travelling twin accelerates; the stay-at-home twin doesn't.
Yes! Look at the title of the page: it says "20 Meg Limit Exceeded". Therefore 20 Meg == 40 Meg, which logically implies that God exists (and is too cheap to pay for real web hosting).
Maybe I just don't understand this, but...
;-)
It seems the key to this experiment is that the observation from the single low peak is different from observation from the two high peaks of the EM burst.
This is crucial.
Nearly all EM bursts created in the laboratory have multiple troffs and crests (highs and lows). Thus, the ``time/energy'' diffraction pattern ought to have been observed or at least present in many other optical/EM experiments.
Now, I don't think the multi-peaked burst is exactly comparable or equivalent to the diffraction grating, but it ought to be similar. However, I don't have the time or patience right now to work out the math (yes, I'm a physicist)... if someone else would like to look into this I would be ever-grateful.
I'll agree that there is some ingenuity in this experiment and perhaps it ought to be included (briefly) in revisions of QM books. Others can make comparable timed femtosecond pulses, so it should be possible to explore other systems where this effect is seen.
Despite the masses of confused people on Slashot, this doesn't extend or challenge out theoretical understanding of quantum mechanics (it is a manifestation of heisenburgs uncertainty principle: E*t >= h). But, it is always comforting to have confirmation of experiment on our side...
Can't wait to see a good paper on this...
It seems very easy to me to come up with two bodies moving in such a way as to make it impossible to determine which one is moving faster, because the answer to that question depends completely on the point of reference in relation to which you determine their veolocity.
The missing peice is accelleration. In the twins paradox for example, theres no way for them to directly compare unless one of them turns around and comes back. That accelleration breaks the symmetry because unlike motion, accelleration is not relative - One body is _Definitely_ acclerating while the other is not.
Why?
Right! Retards are only supposed to moderate.
"the other redundant and repetitive poster"
I feel your pain.
Dr. Elliot's theory of moving dimenstions stands unrefuted.
A lot of crackpot theories stand unrefuted. Not because they are correct, but because it's just not worth any expert's time to refute them.
It would be great if the detractors could use logic and reason in refuting Dr. E's theory, rather than just refuting it by dismissing it.
OK, I'll give it a shot... Bleah. This is as far as I got.
First off, since the universe is expanding, space-time is also expanding, showing that dimensions are moving and expanding.
Wrong. Anybody who says this clearly hasn't understood college level math (or logic). I suggest taking some classes and bone up on the fundamentals, then rewriting your ideas so that they're comprehensible to other scientists.
You may have a future with Rockwell Automation...
--grendel drago
Laws do not persuade just because they threaten. --Seneca
This is point-set topology, right? I got to take a course in that, but I never got to do algebraic. It was pretty interesting, or so I thought. I'm trying to see how much if it I still remember.
So you mean that... the standard topology (with basis all open intervals in the set) on (0,1) is homeomorphic to R^1 (via the arctan function and some trivial algebra to move (0,1) onto (-1,1))? That was the one we'd use most often, the (0,1) interval. At least, I think it was the open interval. Is the closed interval still homeomorphic to R^1? Are all one-dimensional complete sets (e.g., the reals, but not the rationals) homeomorphic to either R^1 or S^1?
Or is point-set stuff totally useless here, and I'm making shit up?
Man, taking all those math courses really served only to point out how little I know about math...
--grendel drago
Laws do not persuade just because they threaten. --Seneca
Secondly - and I'm being very hypothetical here - even though dimensions are implied to be static, surely a reference point within one dimension can move independently of other dimensions? And aren't our observations based on drift relative to the reference point being used?
If I accelerate (and thus alter movement) upwards, then that is relative to where I was - but if I'm bouncing up and down in a moving bus, or indeed, on a planet hurtling through space, I am surely still accelerating relative along the Z axis - with reference to the bus, and only really accelerating along one axis relative to the bus, the road, the sign post, whether or not I was already moving in relation to it or not. And if the bus accelerates while I'm in the air, then it moves forward relative to me or I move backwards relative to it - taking the end with the head lights as the bus' front.
To me, "rotation in 1 dimension" is possible, with a very limited definition of rotation - freedom to change "forward" from a given direction to its opposite. If anyone could define the "1 dimension" part more precisely (of which I believe the hard part is defining "1"), I'd be very interested in the result. But let's assume that rotation means a change in vector, which requires at least 2 dimensions of freedom, and at least one more dimension, so the first two have something to change in.
The fun part is being able to accelerate through time - using relativity theory, or whatever, while moving along a given physical axis. If I can alter a the vector of an object which has freedom in 2 dimensions, surely that's rotation. So if I can alter the vector of an electron with the dimensions being one physical axis, and time, isn't that rotation in the traditional 2 dimensional sense too? Us three-dimensional beings have the luxury of freedom of accelerating in a whole three dimensions - relative to the reference dimension of time. The next factor is that in order to be able to move through the 4th dimension, then there must be a 5th, whose outcome we cannot both determine and measure at the same time. I thought that dimension was probability (or has it been redefined since I last read about it - it's been a while), and this whole probability thing is what quantum mechanics gets all funky with.
It seems to me we're talking about movement through time and space relative to probability. Does this make sense?
Maybe.
You know, I was trying to think of a way to say that it's intellectually bankrupt to attach real value and meaning to isomorphisms between ancient cultures and modern science. (Alan Sokal touched on this when he made his famous jab at postmodern literary analysis.) But you've said it better than I ever could. It's a shame your comment won't be seen by a tenth of the people who saw the parent. (It's at Score:0 as I write this.)
And yet I don't mind when Doug Hofstadter does it. I wonder why that is. Does he say that the isomorphisms are strictly tools for thinking, not rigorous methods of proof? I remember him saying something like that.
The tendency to give this sort of credence to foreign cultures simply because they seem alien is foolish and, I think, a bit demeaning to both science and the culture being reappropriated.
I suppose it'll stick around, though, if only because it's such a useful (but misleading?) tool for teaching the layperson.
--grendel drago
Laws do not persuade just because they threaten. --Seneca
Dear me, that's disturbing. I wonder how many people ended up with really, really sketchy views on science from that.
This, perhaps, is a danger of trying to popularize science---you end up mangling it and turning it into something not rigorous, and thus not really useful.
While these isomorphisms provide a useful view on some ideas (Buddhism's Interconnectedness of All Things and chaos theory's butterfly effect), it's dangerous to assume that those connections are rigorously true, that rather than connecting an unknown idea in the audience's mind to a familiar one, you're saying that the universe really runs on Buddhism. And that ain't science.
--grendel drago
Laws do not persuade just because they threaten. --Seneca
He's the implicate order guy, yes? I remember reading about it in Grant Morrison's Animal Man , and thinking that it just sounded like the whole Platonic cave dealie.
And y'know what? Using the implicate order as an explanation for why fictional characters in long-standing continuities can be reinvented while retaining the central essences of their identities is fine with me. (The whole story centered around the massive rewriting of DC comics continuity in 'Crisis on Infinite Earths', and the characters' attempts to find out just what the hell had happened.)
As for using it as a real tool to describe the universe itself? Smells faintly religious, and not at all like science. Sounds like Bohm had some interesting philosophy, but I'm not really clear on what that has to do with the physical world.
--grendel drago
Laws do not persuade just because they threaten. --Seneca
But for the most part, I agree that rotation in one dimension really doesn't make any sense. Oscillation is possible but not rotation, unless you use parametric definitions like above, in which case it really isn't one dimension after all.
Clickety Click
Bear in mind that Feneman died before the advent of this here interweb.
January 13, 2004
Quantum Astronomy IV: Cosmic-Scale Double-Slit Experiment
by Laurance Doyle
Fascinating reading
Artificial intelligence is the study of how to make real computers act like the ones in the movies.
You actually see the image on the phosphor screen yourself through a window at the base of the column. The image is a bit dim, you you have to have the lights out, but what you see is being imaged directly.
The electrons all have roughly the same energy - a million eV or so - so they are the equivalent of nearly monochromatic light. If your target film varies in thickness, then you get electron Newton's rings because of reflections from the top and bottom surfaces. You can get lots of fringes - out to the 50th or 100th order because the electrons are pretty monochromatic.
Suppose you have a 1 MeV electron beam travelling about 50 cms from your target to the screen. You cannot put more than a few hundred picoamps through your target without frying it. Now you do not get many electrons per second in a picoamp, and they are moving very fast at 1 MeV. I remember doing the sums, and finding out that the whole TEM column for my beam current spent 97% of its time completely empty. The film is only a few nm of this 50 cms, so the odds of it having two transmitting electrons in it at once is really tiny.
You actually see the image on the phosphor screen yourself through a window at the base of the column. The image is a bit dim, so you you have to have all the lights out, but what you see is being imaged directly by the electrons. Or electron, rather, because what you are looking it is the image formed by a single electron interfering fifty or a hundred times with itself after having passed through every point of the target film, and reflecting (or not reflecting) multiple times off each surface.
This as much as anything got me to believe in the wave equations. Trust in the sums and leave your common sense by the door, and it all seems to work.
nothing like banging one that's getting eaten and eating one that's getting banged at the same time.
Obviously only a Nazi would post a time cube link.
...
;)
(The real joke here will be clueless mods marking this as flamebait
"Mind, as manifested by the capacity to make choices, is to some extent present in every electron." -Freeman Dyson
I went to a debate one time where a guy tried to prove the existence of God mathematically, but I wrote down his argument while he was giving it, and there was some obvious logical falacy where he went from something like a->b back to b->a, which didn't make any sense when you thought about it. It had something to do with causality.
:^)
At any rate, I can't find my notes... maybe god stole them.
"I have never let my schooling interfere with my education." - Mark Twain
No, he wasn't wrong. And neither were you, other than to claim he was wrong. He never said anything about turning around. If no one turns around then he was correct. If someone does turn around then you are correct.
I've got one word for you, dude: Paragraphs.
there's no way of determining which of the two bodies will age more quickly and at what rate they will age in relation to each other
Correct, if no one accellerates. So long as they are moving apart then there is no way to determin which is "aging more quickly". For some observers the first one will age faster, and for other observers the second will age faster. The farther apart they get the bigger the discrepance can become. If they are one light-year apart then either one may be seen as up to one year "older" than the other. If they are 10 light years apart then either one may be seen as up to ten years older than the other.
Time can only be compared locally, when they are at the same spot. If they are travenlling at different speeds then they can only be at the same spot once, and then constantly moving apart. Since you only have one time-point you cannot make any "duration" measurments that apply to both. The only way to measure a duration for both of them is to have them at the same location twice, and in order to do that at least one of them needs to accelerate and "return" to the other one. That acceleration will cause that one's space/time axes to "twist". It's hard to explain that "twist" in words, but it's pretty clear in pictures. Anyway, that acceleration and "twist" causes that one to see the other one suddenly age. The one that accelerates and "twists" is the one that has aged less when they get back together. It is acceleration that causes time to "slow down".
Standing here on earth we are constantly accelerated by gravity even though we don't move. That gravitational acceleration causes our clocks to run slower than someone floating out in space. If you could stand just outside a black hole that enormous gravity and enormous acceleration causes your clock to run very slow.
-
- - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
You set up three double slit experiments in sealed boxes. You record whether there is an interference pattern and you record which slit every particle went through, but no one observes any of the experiments.
After the experiment, you randomly choose one machine. You throw away the records of which particle went through which slit for the other two machines. Then you look at the three records for interference and the one record of which particle went through which slit.
You will have interference for the one whose slit results you have observed, and not for the others (as you didn't observe the results).
Thus the future can be predicted.
Set up the experiment again, but this time allow a volunteer to choose which slit records to view. Before they even choose the record, you will be able to predict which one they will choose by using the interference records (as long as you are careful to destroy the other slit records after).
100% accurate future prediction. You could make a great magic trick out of it.
"...if we trace the path of a photon on a space-time diagram, the only way for a photon to remain stationary in space-time is to move at the speed of light, or to keep up with the expanding time dimension..."
Nuts, mate. What about multidimensional orbits? A photon orbiting in 4 dimensions would appear to interfere with itself in 3 dimensions (it'd enter the same 3d space twice). You could probably say the same with more dimensions but I don't want to think about that while I'm working.
you get the worst refute in history award for that. details please.
what?
This doesn't sound entirely copacetic to me. Why would one see an interfrence patttern with time uncertainty? It seems that the energy-time uncertainty principle would be at play here and one would see some sort of energy variation rather than spatial interference. Maybe I'm misunderstanding things.
Come on. Stop it. You KNOW he was trolling. Just because you could easily refute what he scribbled here doesn't mean you should have.
same story...two posts...lots of interference caused :)
Find a job you like and you will never work a day in your life.
Oh my god. What the hell is it???
What modern Obelix would say today? Of course, "Those crazy Americans!".
You don't have to be a "math god" to see the problems with the "theory".
I'd estimate a solid high school physics class ought to provide sufficient background.
Slashdot quality declines as the number of hot grits posts decreases. - Provolt's Law, Apr-09-2005
> Hmmm... firstly, although mathematics is
> indeed a very precise language, it still fails >to define the number 1.
One is precisely defined as (0)
{ {} }
the set containing the null set (defined as zero) as its only member.
Two is {0,1)
{ {}, { {} } } , etc.
A møøse bit your sister once? Was is very nasti?
I have to stop wasting so much time reading Slashdot. It's interfering with my crystal meth addiction.
It's all explained here--the time dimension is moving relative to the spatial dimensions, manifesting itself as a spherically-symmetric expanding wavefront through space: http://physicsmathforums.com/forumdisplay.php?f=55
Allow me to attempt some answers to your questions:
(A) How do you propose to measure velocity using only measurements of the time dimension? Last I checked, velocity is defined as (spatial units translated)/(temporal units translated).
ANSWER:
We must use the four-veloicty here.
Even when an object is stationary in space, it still moves with a vecocity of c through time. Einstein said this.
As Brian Greene points out in the Appendix to Chapter 2 of The Elegant Universe, we note that from the space-time position 4-vector x=(ct,x1,x2,x3), we can create the velocity 4-vector u=dx/d(tau), where tau is the proper time defined by d(tau)^2=dt^2-c^-2(dx1^2+dx2^2+dx3^2).
Then the "speed through space-time" is the magnitude of the 4-vector u,((c^2dt^2-dx^2)/(dt^2-c^-2dx^2))^(1/2), which is identically the speed of light c. Now, we can rearrange the equation c^2(dt/d(tau))^2-(dx/d(tau))^2=c^2 to be c^2(d(tau)/dt))^2+(dx/d(tau))^2=c^2. This shows that an increase of an object's speed through space, (dx/d(tau))^2)^(1/2)= dx/d(tau) must be
accompanied by a decrease in d(tau)/dt which is the object's speed through time, which also may be considered the rate at which time elapses on it's own clock d(tau) or the proper time, as compared with that on our stationary clock dt.
The only way to stay stationary in space is to move through time with the velocity of c (mass at rest).
The only way to stay stationary in time is to move through space with the velocity of c (photon).
Thus the spatial dimensions and time dimensions are moving relative to one-another.
How else to explain that by staying still in one, you are moving through the other, and vice versa?
(B) If we simply look at this in two dimensions, restraining spatial coordinates to the x direction, and our second dimension being time, your theory would have the origin of the t axis sliding up and down, while the x axis remains stationary. While this will change the appearance of our visual rendering of the coordinate system (for example, we may draw the x axis intersecting the t axis at t=-4s, for instance), it is simply smoke and mirrors. An event at (t1,6) will always be 4m away from an event at (t1,10). An event at (t2,-5) will always be |t2-t3| away from (t3,-5), no matter how much you shift the numerical origin of your t axis. My point is this: any coordinate system is relative to an arbitrarily chosen origin. While you may renumber your t axis as often as you wish, and thus have it "slide" to and fro relative to your other axes, the relative spacetime differences between events will remain the same.
The answers to (a) and (c) should make this apparent.
(C) Sorry, ran a bit long on (B), so i'll make this my last point. This point is one of semantics. You state that the time dimension expands as a spherically symmetric wavefront through space. Thus, you feel the time dimension has spatial components. Therefore, your time "dimension" is not a dimension at all, as it contains an x, y, and z component, each which
have a _set_ relationship to one another (they define a sphere, as you explicitly state above). For time to be its own dimension, it must be
possible for any relationship of x, y, and z to exist at any point t. Perhaps you stated this in a way you did not intend, or perhaps you simply can't wrap your head around four dimensions.
Answer:
The projection of a sphere in two dimensions is a circle.
The projection of the fourth dimension in three dimensions is a sphere.
For a photon to stay stationary in time, it moves through space with a velocity of c.
Think about that--the photon stays stationary in time, while moving at a velocity of c relative to the three spatial diemensions.
It expands as a spherically symmetrical wavefront by staying stationary in time.
Therefore, time must be expanding in a spherically symmetric manner throughout space.
Thanks for the feedback!
But then you must define set theory...
I was hoping to see better arguments against Dr. E's theory of moving dimensions.
6
But I have to agree, it does stand unrefuted.
http://physicsmathforums.com/showthread.php?t=1
The time dimension is moving relative to the three spatial dimensions. Such a concept may be used to explain physical phenomena found in relativity and quantum mechanics. The constant speed of light, time dilation, Lorentzian contraction, wave-particle duality, the equivalence of mass and energy, the gravitational red-shift, and the second law of thermodynamics may all be explained on a deeper level by a theory of moving dimensions. Such a theory may also offer a path for the unification of Quantum Mechanics and Relativity.
The only way to stay still in the three spatial dimensions is to move at the velocity of light c through time. The only way to stay still in the time dimension is to move at the velocity of light c through space. How else can this be explained, but with space and time coordinates are in motion relative to one-another?
Best,
McCoy
I'm sorry, but Meetch's post has no basis in actual knowledge of the subjects he's talking about.
Meech, I was gonna rip appart your post nearly sentence by sentence...but what I'll say is this: go get a great big book on calculus and read it (try a book by Stewart). Discover for yourself what 'rotation' really means in the mathematical sense. Then get a general introductory text to special relativity, and read that, so you have an understanding of what dimensions actually mean, and get acquianted with something called space-time. Finally, go get a book (I recomend Griffiths) on quantum mechanics, so you know how probability is used by physicists and you'll stop talking about 'movement through time and space relative to probability'.
Your kind of ignorance is dangerous: it might lead people who honestly don't know about this stuff to think you even have an inkling of an idea of what you're talking about, when you most obviously don't. If you don't know what you're talking about, don't talk about it.
-- Waht? Tehr's a preveiw buottn?
That's twice now! Stop! Get up and walk away from the keyboard. Get some fresh air and exercise. You put one leg in the trap and went ahead with sticking the other one in there! Madness, of course.
There is an interesting series of articles about quantum astronomy at http://www.space.com/searchforlife/quantum_astrono my_041111.html
. It discusses the weirdness of the double slit experiment. They are now trying to do an experiment with light coming from a sun exploding at about a billion light years away from earth and using two super galaxies as the two slits. They than stated by changing how we measure that light we somehow effect how that light was transmitted which occurred over a billion years in our past. To me that would mean that we can somehow communicate with the past.
A single entity
The standard distance between consecutive integers
The number of different empty subsets in any set
The multiplicative identity element
There are quite a few others as well.
Mathematics is the only precice language, any language that attempts to describe it can only be less precise.
And an Electron in the stink.
Talk about your charmed spin!
Huh???
First a warning: IANAP, and it's been atleast 10 years since I've had a physics class. I haven't used anything from my modern physics class (mostly wave functions) since then. Heck, I haven't even used calc or dif eq for atleast 10 years. So I might be wildly off here.
If I'm understanding it correctly, there's an argon atom sitting there. The light pulse comes along and causes it to emit an electron -- the peaks cause it to emit the electron towards one screen, the trough cause it to emit the electron towards a different screen. The laser pulse they used had 2 peaks and one trough -- 1.5 cycles.
The fastest the electrons would travel would be at the speed of light. So we should be able to calculate the maximum distance the first electron could travel before the 2nd excitation happened:
c * delta time = distance traveled
(3*10^8 m/s) * (5*10^-15 s) = 15*10^-7 ~= 10^-6 m
Now, that distance doesnt mean much to me. If we compare it to the diameter of an argon atom (found via google), we get:
diameters traveled = distance traveled / diameter
10^-6m / 4*10^-10m =.25*10^4 = 2500 diameters
So, if our electron is traveling at the speed of light, it's about 2500 diameters away. Obviously it's going to be moving much slower than that. I'm going to guess that it's much less than 1/2500 c.
So, isn't it possible that the first electron is still quite close (possibly still within the argon atom) when the 2nd peak excites the atom? Might they be close enough to interfere in a way that is consistent with what we already know?
Thanks!
I was looking for something like this!
Moving Dimensions & Entropy:
Because time is expanding as a spherically symmetric wavefront through the three spatial dimensions, photons, as well as all matter that interacts with photons, exhibits a probability to move in a spherically symmetric manner. Thus, if we have a clump of atoms in the middles of a room, a probability exists for the atoms to spread apart in a spherically symmetrical manner. at each point in space, they exhibit a probabilty of moving along any of the three spatial coordinates, carried along by the expanding time dimension.
Thanks for the link to Dr. Ord's work!
Best,
Elliot
I knew it was my future self wreaking havok on my present self
----- If communism is a system where the government owns business, what do you call a system where business owns govern
I think you need to be careful of conflating "dimension" with "distance". In an expanding universe, dimensions don't "move" by increasing distance or angular separation. They become more "dense" with distances between their existing points, filling in each infinitesimal subdistance with more distance. So the expanding sphere of time you describe wouldn't be measurably expanding the distance from its outermost extent relative to other dimensions, but rather expanding the distance between that outermost extent to its center, with added distance "created" between the center and the end. That's not necessarily to refute the principle of a moving time axis, but rather that the physical experience of the mathematics is not consistent with the rest of the physical experience of the rest of the mathematics. There could be another way we experience the physical movement of a time axis, if the rest of the math is valid.
--
make install -not war
lthough mathematics is indeed a very precise language, it still fails to define the number 1.
Try looking in here or here both of which conveniently go to some trouble to very explicitly define 1 and number, etc. Philosophy of mathematics has a much mre solid grounding than you apparently imagine.
Secondly - and I'm being very hypothetical here - even though dimensions are implied to be static, surely a reference point within one dimension can move independently of other dimensions? And aren't our observations based on drift relative to the reference point being used?
Welcome to the world of not understanding dimension as used in special and general relativity. It's on a manifold, which is coordinate system indpendent - that's the whole point really - you're talking about moving the coordinate system, when the whole point is that it doesn't matter.
To me, "rotation in 1 dimension" is possible, with a very limited definition of rotation - freedom to change "forward" from a given direction to its opposite.
Actually think about what you're saying for change. Motion (even in one direction) requires time, which we've already said is just another dimension in spacetime, so to have motion we have 2 dimensions and we're not talking about rotation in 1 dimension any more, but in 2. It helps if you pay attention in class, honest.
Does this make sense?
Not in the least, and I shouldn't even be bothered spending nthe time replying, but I'm bored. Please, go read some books on the subject(s) before shooting your mouth off randomly.
Jedidiah.
Jedidiah.
Craft Beer Programming T-shirts
Hello!
= 55
General relativity demonstrates that massive objects warp space-time, meaning that as a massive object moves though space-time, it stretches space-time, showing again that space-time in one area can move, or deform, relative to space-time in another area.
The time dimension is constantly expanding, relative to the three spatial dimensions.
Spherical Symmetry of Photon Propagation:
Quantum mechanics teaches us that a photon propagates as a spherically-symmetric wavefront. This is because a photon is mass rotated into the time dimension, which is expanding as a spherically-symmetric wavefront.
Spherical Symmetry of Time Expansion through Three Dimensions:
The projection of a sphere in two dimensions is a circle. The projection of the fourth dimension in three dimensions is a sphere. And because this fourth dimension, time, is expanding, it appears as an expanding sphere. For a photon to stay stationary in time, it moves through space with a velocity of c. Think about that--the photon stays stationary in time, while moving at a velocity of c relative to the three spatial diemensions. It expands as a spherically symmetrical wavefront by staying stationary in time. Therefore, time must be expanding in a spherically symmetric manner throughout space.
http://physicsmathforums.com/forumdisplay.php?f
But in order for the twins to meet again -- to compare the clocks -- the travelling twin has to turn around (accelerate). If instead they meet because the second twin accelerates to meet the original traveller, their clocks are not different.
With space and time axes that are orthogonal to each other, and a rule that total velocity (space and time) be equal to c?
Light moves at c through space and thus at velocity 0 through time. We move at a very slow speed through space, and move at a large fraction of c through time. Something standing completely still space-wise moves at c through time (this explains why something in motion, even a small amount of motion, experiences a time lag compared to something standing still)
But that's just a theory. Doesn't rely on dimensions that move relative to each other.
Also, how can an axis orthogonal to another axis move against it? If they're orthogonal, they're orthogonal everywhere. Maybe his theory relies on non-orthogonal dimensions?
From Dr. E's Theory of Moving Dimensions
= 57
Spherical Symmetry of Time Expansion through Three Dimensions:
The projection of a sphere in two dimensions is a circle. The projection of the fourth dimension in three dimensions is a sphere. And because this fourth dimension, time, is expanding, it appears as an expanding sphere. For a photon to stay stationary in time, it moves through space with a velocity of c. Think about that--the photon stays stationary in time, while moving at a velocity of c relative to the three spatial diemensions. It expands as a spherically symmetrical wavefront by staying stationary in time. Therefore, time must be expanding in a spherically symmetric manner throughout space.
http://physicsmathforums.com/forumdisplay.php?f
Einstein proclaimed that all objects travel through space-time at c. Even though we perceive a ruler along the x axis to be stationary, it is yet traveling through space-time at the fixed speed of c, implying that time is moving through it. Rotate it towards the y axis, and its projection upon the x axis shortens, yet it still appears to be stationary, and it is still traveling through space-time at the rate of c. Rotate it into the time dimension, and it's projection along the x axis still shortens (Lorentz contraction), but now it begins to move through the three spatial dimensions, while maintaining the fixed speed of c through space-time. Again, we see it move through the three spatial dimensions as it is rotated into the time dimension because the time dimension is moving relative to the three spatial dimensions.
As Brian Greene points out in the Appendix to Chapter 2 of The Elegant Universe, we note that from the space-time position 4-vector x=(ct,x1,x2,x3), we can create the velocity 4-vector u=dx/d(tau), where tau is the proper time defined by d(tau)^2=dt^2-c^-2(dx1^2+dx2^2+dx3^2). Then the "speed through space-time" is the magnitude of the 4-vector u, ((c^2dt^2-dx^2)/(dt^2-c^-2dx^2))^(1/2), which is identically the speed of light c. Now, we can rearrange the equation c^2(dt/d(tau))^2-(dx/d(tau))^2=c^2 to be c^2(d(tau)/dt))^2+(dx/d(tau))^2=c^2. This shows that an increase of an object's speed through space, (dx/d(tau))^2)^(1/2)= dx/d(tau) must be accompanied by a decrease in d(tau)/dt which is the object's speed through time, which also may be considered the rate at which time elapses on it's own clock d(tau) or the proper time, as compared with that on our stationary clock dt.
Philosophical and Physical Barriers to Moving Dimensions
Many trained physicists have a knee-jerk reaction that the time dimension cannot be moving because "dimensions cannot move." First off, since the universe is expanding, space-time is also expanding, demonstrating that dimensions are moving and expanding. Secondly, general relativity demonstrates that massive objects warp space-time, meaning that as a massive object moves though space-time, it stretches space-time, showing again that space-time in one area can move, or deform, relative to space-time in another area. Thus there exist neither philosophical nor physical barriers to the concept of moving dimensions, but for artificial ones within lazy minds.
Rather than just accepting the minus sign in front of the c^2t^2 as being there because it "just is there," this paper aims to look at the deeper reality which gives rise to the minus sign. A physicist's job is not to accept things on blind faith, nor only ask questions that are allowed to be asked, but a physicist's job is to wonder. And that wonder, which seems all but forgotten in the bureaucratization of modern physics, leads to the deeper beauty. "Imagination is more important than knowledge," was how one physicist put it.
I think I got the circle vs. line. But if a line in your space has to go through two rotations to close the curve (a Mobius strip), is that still homeomorphic to a closed curve drawn in a normal strip that only takes a single rotation?
We are the 198 proof..
everything in relativity seems to be relative to your frame of reference. So, the clock that was whirling around space at high speed, from its own perspective it is standing still and we, earth, the other clock is the one moving fast. So when they come together again, not only do you see that the returning clock has slowed, but it sees that you have slowed. Someone please explain that, cuz that has always been were I said the theory has to be wrong.
you'll just have to trust me when I say there is *nothing* of value in your idea.
This sort of response is not warranted even if the parent post contained random line noise. He wasn't being rude to you, and you've been nothing but condescending to each of the people to whom you've responded.
Turn it down a notch, Jack. That we're not all physicists isn't a personal insult to you.
StoneCypher is Full of BS
You know, grandparent post was quite clear in that he was looking for a reply which would explain things rather than to dismiss them, and what you did was to turn around and dismiss what he had to say as based on apparently flawed math or logic, with no explanation whatsoever.
Furthermore, what he said is a tenable fringe belief in physics, and there is not in fact a good contradiction of his viewpoint currently known. The next time you choose to take such a tone with someone, have the decency to explain yourself, or to be utterly silent.
If you want to tell me I'm wrong, you will have to give a specific explanation of why, including examples and a counter-argument. What you did to the grandparent was nothing better than to waste his time karma whoring.
StoneCypher is Full of BS
I think Mr. Ray is at the pinnacle of meaningless drivel
Then you have entirely missed the point of that website. You might as well say that Landover Baptist was a heretic church, or The Onion a disreputable journal of opinion.
Just because it's stupid doesn't mean the author is stupid. Feel free to learn about humor. It'll help you in the interactions with mammals.
StoneCypher is Full of BS
No matter where you start in any formal mathematical system there are always undefined terms.
Anyways... =)
-pVoid
Here's a few ideas:
- As you point out, gravity and acceleration are to some significant extent functionally identical.
- The universe is constantly expanding.
- What of the possibility that this expansion is, in fact, the root cause of "gravity"? I.e., what if the observable effects of gravity are in fact caused by acceleration as everything expands?
This last idea has been bothering me for some time. I'm quite interested to hear (read) what your thoughts might be.Now if we add ideas 1 and 2 to arrive at 3:
"What in the name of Fats Waller is that?"
"A four-foot prune."
You -can- rotate in one dimension - it would just mean to multiply by -1.
..
A pretty boring rotation, but well
I'm still trying to figure out what people mean by 'social skills' here.
They'd do the experiment with two eyed needles and a camel sent through, a few molecules at a time, and state "hey, Jesus didn't specify the camel had to stay alive..."
No, that wouldn't be, as rotation has to be gradual. It may be the best approximation we can do, but the graduallness of rotation is needed.
This post written under Gentoo-linux with an SCO IP license.