Slashdot Mirror
Quantum-Tunneling Electrons Could Make Semiconductors Obsolete
Nerval's Lobster writes "The powerful, reliable combination of transistors and semiconductors in computer processors could give way to systems built on the way electrons misbehave, all of it contained in circuits that warp even the most basic rules of physics. Rather than relying on a predictable flow of electrons that appear to know whether they are particles or waves, the new approach depends on quantum tunneling, in which electrons given the right incentive can travel faster than light, appear to arrive at a new location before having left the old one, and pass straight through barriers that should be able to hold them back. Quantum tunneling is one of a series of quantum-mechanics-related techniques being developed as possible replacements for transistors embedded in semiconducting materials such as silicon. Unlike traditional transistors, circuits built by creating pathways for electrons to travel across a bed of nanotubes are not limited by any size restriction relevant to current manufacturing methods, require far less power than even the tiniest transistors, and do not give off heat or leak electricity as waste products, according to Yoke Khin Yap of Michigan Technological University, lead author of a paper describing the technique, which was published in the journal Advanced Materials last week."
You mean the 1950s are back? Tunnel diodes were supposed to rule the world back then too! How exciting!
We won't see this tech for at least 20 years before it get's applied to consumer products, if at all.
OTOH, it is exciting to see the kinds of research being done that will advance computing beyond our wildest dreams.
Except, you know, space itself. Period.
Light travels faster than light all the time. It propagates at different rates depending on the medium, DERP.
Look, it's not a religion, you were taught a set of beliefs and you refuse to question them. Why?
period.
Phase velocity exceeds c, not group velocity. If you guys wanna prove Einstein wrong, you're gonna have to work a little harder.
quantum tunneling, in which electrons given the right incentive can travel faster than light,
I know stuff can go faster than light, provided no information does, but I am not sure that happens in tunneling. Does it?
Dear OP, transistors are f****** semiconductors! The rest of the article is at best starry-eyed fantasy.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
It does. Tunneling is instantaneous. It may even be able to transfer information, but the jury is still out on that and classical quantum mechanics says it cannot. If it can, then it can transfer information without time delay, but only over short distances and with a large energy investments that almost completely goes into losses. That way, it would basically never happen in nature and it cannot go over significant distances.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
Wrong. Tunneling is instantaneous and it is a well-established mechanism. It has severe distance limits and the question is whether it can transfer information FTL.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
You can't, by definition, transgress the laws of physic. If you think you transgressed such a law, your observation is wrong or what you know about the laws is wrong. Either way, you should not say you "transgressed the laws of physic". Please stop doing it.
Tunneling is instantaneous. A tunneling electron (for example) jumps from one position to another. It does not cross the intermediate space, so you can say it actually does not go FTL, because it does not "travel" in a very real sense. Tunneling is a very well established effect. For example in Zener-Diodes with 5.6V about half of the noise produced is tunneling, and about half is thermal.
So, sorry, you are wrong. What is unclear though is whether tunneling can carry information. There is some indication that it can, but it would probably be severely distance limited (read: centimeters to meters at best) and hence not play any role in the larger scheme of things.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
You seem not to have understood the difference between science and religion.
In science, we don't currently have a theory for faster than light travel ... except of course for entangled particles whose properties appear to propagate with infinite velocity. This doesn't mean that we won't have a theory that covers FTL in future. Only religion has such a priori absolutes. Science embraces anything that reality feels like manifesting to us.
There is no "period".
Found this on wikipedia:
http://en.wikipedia.org/wiki/Faster-than-light#Faster_light_.28Casimir_vacuum_and_quantum_tunnelling.29
Faster light (Casimir vacuum and quantum tunnelling)
Raymond Y. Chiao was first to measure the quantum tunnelling time, which was found to be between 1.5 to 1.7 times the speed of light.
Einstein's equations of special relativity postulate that the speed of light in a vacuum is invariant in inertial frames. That is, it will be the same from any frame of reference moving at a constant speed. The equations do not specify any particular value for the speed of the light, which is an experimentally determined quantity for a fixed unit of length. Since 1983, the SI unit of length (the meter) has been defined using the speed of light.
The experimental determination has been made in vacuum. However, the vacuum we know is not the only possible vacuum which can exist. The vacuum has energy associated with it, unsurprisingly called the vacuum energy. This vacuum energy can perhaps be changed in certain cases.[38] When vacuum energy is lowered, light itself has been predicted to go faster than the standard value c.
"I think this line is mostly filler"
He wants his junction back
Some drink at the fountain of knowledge. Others just gargle.
Quantum theory and relativity aren't exactly in agreement. That is especially true when it comes to terminology that surrounds the physical interpretation of the mathematics, but it may also be true of the physical interpretations themselves.
Can't the slashdot editors be more active with their copy? Nothing goes faster than light. period.
Not true. A shadow can move faster than light. If a wavefront is impacting a linear object, the impact point can move far faster than the propagation speed of the wave. Researchers have found numerous "action at a distance" phenomena that occur instantaneously between entangled particles. None of these phenomena can transmit information, but they are still faster than light.
Can't the slashdot editors be more active with their copy? Nothing goes faster than light. period.
Correction: no information travels faster than light. It is easy to imagine a system which looks like something is moving faster than light: shine a bright enough torch on the moon. If you move the torch fast enough it will look like the spot on the Moon is moving faster than light. This is perfectly fine because there is no way to change the where the beam moves if you happen to be where the beam is pointing at a particular time i.e. no information flows between one spot and the next because everything is under the control of the torch wielder back on earth.
In QM tunnelling the transmission speed of information is always below the speed fo light and so there is no problem (if you know secondary [high] school physics this is like the difference between phase velocity and group velocity of a wave in a wave guide). However where the editors messed up is the statement:
...in circuits that warp even the most basic rules of physics.
These circuit DO NOT warp the basic rules of physics. Quantum mechanics IS a "basic rule of physics" - it is certainly counterintuitive but it is a fundamental rule of physics.
My corollary to Betteridge's law of headlines: If a title has "could" in it, you can replace it with "probably won't".
Put up is one option. Shut up is the other option.
And a third option is to shit on the troll instead of throwing food over the bridge.
W..w..W - Willy Waterloo washes Warren Wiggins who is washing Waldo Woo.
What is unclear though is whether tunneling can carry information. There is some indication that it can...
No that is clear - it cannot. If it could, and if there was any indication that it could, it would be direct evidence of the violation of causality. This is a "Big Thing" at ANY scale because all I have to do is find an intertial frame where the receipt of the information precedes its reception and then stop the information being transmitted. Having this restricted to a distance of a few cm just makes the resulting paradox less entertaining, but just as implausible, as the ones you see on Star Trek.
the problems:
BQP=BPP?
P=NP?
Those problems have nothing to do with speed of propagation of information. Structure of space is not implied by the Turing computation model.
A shadow can move faster than light. If a wavefront is impacting a linear object, the impact point can move far faster than the propagation speed of the wave.
These are only apparent movements. If I point a laser pointer to a wall, I may say “the dot moves” and everyone will know what I mean, but actually there's nothing moving there, it's only the location where the light from the laser pointer is hitting the wall that's changing.
Obviously I could calculate a velocity anyway and make that velocity greater than the speed of light by choosing the distance between laser pointer and wall big enough, but if it's all about whether you're able to assign a velocity, you may as well calculate the velocity of thoughts: Divide the distance of two places by the time you need to switch between them in your mind. Just look at the sun (or some more distant star to avoid eye injuries) and then at your desk and you're well above light speed.
The ability to define a velocity does not imply that something's moving.
(So, technically, those examples are “faster than light”, though I'd dispute whether something actually “goes faster than light", as the OP phrased it)
Nothing you said made any sense. You took a physics problem and called it equivalent to two computational problems that are unrelated to the physical problem, related to each other, but not in any way equivalent.
"whether relativity settles FTL (it doesn't)" is word soup.
This article seems to disagree with you:
http://www.gizmag.com/quantum-entanglement-speed-10000-faster-light/26587/
Usually Nerval's Lobster promotes self-described tech-writer-gun-for-hire/Slashdot "editor" Nick Kolakowski's work. In this case, the author of the Slashdot content is Kevin Fogarty, who recently brought us such gems as thinly-disguised press releases for Cumulus Networks, Enterasys, and Heavy Reading, all of which use curiously-similar ambiguous stock photos from Shutterstock... My guess: the people behind the article (which we can't read) paid for it to be summarized and posted on Slashdot so they could pursue further funding by claiming their work has been "featured" (legitimized) on Slashdot.
This has been going on for some time now with Nerval's Lobster. Many people have learned not to feed the troll (don't post comments on Nerval's Lobster submissions), but if you're just joining us, welcome! And try not to feed the troll.
It's not accurate at all. Why are you substituting one even more implausible untruth for another?
But what if you have a mile long pole and correlate it's movements into a form of communication. As soon as you move the pole on one end it would instantaneously move on the other for instantaneous communication. trollface.jpg
The Official Site of 1337 Pwnage
>classical quantum mechanics says it cannot.
"Classical quantum mechanics."
OK, with that phrase, my Physics degree is officially obsolete.
Now I wonder how much time my Ph.D. in Economics & Statistics has left on it . . .
hawk, fortunate that his J.D. won't expire . . .
The reason why this is not a problem is because the electron does not actually travel from one point to the other, which would mean there were intermediary points of existence along the way. This is a quantum movement. The electron stops probably being at one place and becomes more probably in another place. It never was in any “place” to start with since placeness is not a quality of an lepton in motion.. Nevertheless, the event of the movement from one probability to the next is not really time measurable as an event, only as a measured effect.
But what if you have a mile long pole and correlate it's movements into a form of communication. As soon as you move the pole on one end it would instantaneously move on the other for instantaneous communication.
Nope. The motion propagates to the far end at the speed of sound in the pole - much faster than sound in air, but glacial compared to light in vacuum.
Don't bother looking for an unobtanium with near-infinite stiffness and an internal speed of sound faster than light-in-vacuum. The motion at one end encodes information about what is happening at that end and that information is propagated down the pole by interactions between the pole's component particles, interactions that all are no faster than the speed of light.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Yep, you nailed it. That way you can have a wave propagate it's phase faster than light. The tunnel effect experiments I have seen all relate to this phase velocity. And really nothing new. A wave propagating in a gold or silver film will also see the real part of the refractive index being lower than one, and thus go faster than C. However, information can not go faster than light. The article mentioned here, is just a case of successful scientific advertising. It looks good, sounds good but really nothing new.
Wow, just imagine a beowulf cluster of whatever this article is about...
The first smelted iron in the history of our species was found in East Africa
Put that in your pipe, you waste of oxygen, and smoke it.
The world's burning. Moped Jesus spotted on I50. Details at 11.
You could say its NEO. But as the Double slit experiment shows everyone is capable of being Neo.
In other worlds, this quantum computer technology will only work if there are no humans to observe.
What the article is not telling is that this technology already exist and in operation. but no human is allowed to observe it.
But space isn't something. Period. That's why expansion of distance between two somethings with nothing between can exceed light speed.
As far as we understand it right now, I should add.
I've fallen off your lawn, and I can't get up.
On a TED talk, the speaker said electrons travel the speed of spreading honey in wires.
Is that related to your point and the benefits of this technique?
She was like chocolate when she drank... semi-sweet at first and then increasingly bitter.
When I was young kid, in the early 1960's, I visited a ham radio operator a bunch of times. Cool radios, etc. He taught me some key things about tubes, started a long slide into technology that still hasn't stopped. I asked him about transistors. He looked at me somewhat askance and said "yeah, "I heard about them things. Tubes, son. I know tubes." And went back to teaching me about tubes, and resonance, and etc. Outside of his place, I hooked into an NRI electronics course, and spent a summer sucking that down, while running to my older friend Tony to help me with the math. NRI was teaching tubes then too, but they had an excellent section on transistors, and so I grew comfortable with them just as they were becoming interesting and more widely used. Tubes, except for certain specific jobs, just aren't used much now as we all know, and I've always been grateful for my luck in terms of timing; a few years earlier, and I'd have been looking askance at transistors myself. But instead, I've been comfortable with semiconductors right up until they got too small for me to handle (surface mount, trembling hands, etc.) And I know tubes.
The idea that another revolution of similar importance may happen in my lifetime...
Damn. I just feel like one amazingly lucky fellow. :) Now, will I be able to grasp the tech if it makes it to market? That, as they say, remains to be seen. Getting older doesn't mean you're without a clue. It just means you no longer always know where you put them.
I've fallen off your lawn, and I can't get up.
I don't understand that explanation, but anyway...
I know a few famous physicists that would disagree with you on your argument that space is "nothing" and isn't "something." "Empty space" isn't actually empty at all, and space-time itself has lots of intrinsic properties. I believe there's a NOVA special on the subject available online for free if you'd like to investigate.
For instance, if you were to start spinning in empty space and no other matter or light in the universe existed (yet you were still somehow alive), you would still feel your arms being pulled outward due to your spinning motion -- even though you had no point of reference to even know that you were spinning at all. You'd still be spinning in relation to the invisible framework of space-time.
On an unrelated note, there is a controversial quantum theory that light speed in empty space is not a finite speed, but an average speed. Further, an expansion on that same theory is that photons travel at infinite speed, but in the medium of empty space, they randomly hit virtual particles which absorb and re-emit them which is what slows them down to what we measure as light speed. The rate of hitting virtual particles can be predicted statistically and works out to be in line with what one would expect in order to get the current measurement for light speed, but it could all be wishful thinking and tinkering with math.
Because
1) No one's managed to get relativity and quantum effects to line up with each other yet.
2) Relativity doesn't ban traveling faster than light, it bans accelerating to the speed of light.
This it? http://video.pbs.org/video/2163057527/
It does. Tunneling is instantaneous.
It may be instantaneous, but what, if anything, is actually "travelling"?
systemd is Roko's Basilisk.
I see this effect of electrons arriving before they departed as a bonus. Imagine a beowulf cluster of slashdot servers built on such tech.... Then they can post the dupe before the original fine article!
Free, as in your money being freed from the confines of your account.
So, reading that text file (text file? Also, did you count the number of exclamation marks?), this guy did a $1000 experiment which showed that the speed of light, one of the most widely studied and precisely quantities in physics for the last 200 years, is wrong? Right...
systemd is Roko's Basilisk.
1) no matter how fast you move the torch, you will not see the torch's shadow move faster than the speed of light. The shadow will not be in sync with the torch's position, it will lag behind.
What you said violates the principle you stated, i.e. no information can travel faster than the speed of light. But a shadow could be used like a signalling device, and so if it appears to be moving faster than light, then we would have information transmitted faster than light as well.
2) Quamtum tunneling is indeed faster than light, but if it is used for calculations then it will also violate the principle you stated. I.e. if an electron goes from place A to place B faster than light, then information will have been received faster than light since we will know of that fact.
https://www.youtube.com/watch?v=8w9eoZtnJSA
Period.
I have determined that my sig is indeterminate.
Wouldn't that disagree with the fact that the measured speed of light in vacuum, by any observer traveling at any speed, is the same? If the speed of light is just a matter of light being slowed down by virtual particles, there's no reason why your own speed wouldn't be added to or subtracted from the speed of a particular beam of light. Relativity would just go right out the window, we're back to aether theory.
Wrong. Dirac did. And it led him to the prediction of antimatter. And all quantum field theories are relativistic quantum mechanics.
What hasn't yet been managed is to unite general relativity and quantum mechanics. However that's irrelevant for the FTL tunneling question because the speed of light limit is a property of special relativity, which has completely and fruitfully been united with quantum mechanics a long time ago.
Relativity tells us that if we could travel faster than light, then we could also violate causality. So unless you are willing to give up causality, relativity indeed does ban travelling faster than light.
Here is a simple 1d simulation of a particle tunneling through a potential barrier:
https://www.youtube.com/watch?v=cV2fkDscwvY
As you can see, the signal does not propagate instantaneously through the barrier when tunneling. This matches what I learned at school too. What are your sources for tunneling being instantaneous? Do you have some time-dependent simulations that show how the wave function behaves during this instant tunneling?
They're talking about the group velocity of the electrons.
Faster than light expansion is just a mathematical oddity caused by the use of a particular coordinate system. Not that there's anything wrong with it, just that nobody ever seems to explain it properly.
Local distances and times are easy to measure objectively using clocks and measuring rods, but the definition is not so clear and unambiguous anymore when you're talking about large distances in the expanding universe. Different metrics exist, defining distances, times and speeds in a different way, yielding wildly different values while giving the same tangible results for any actual event. I will give you two ways of looking at the universe: the first conserves the speed of light but looks very weird, while the other looks more normal but does not respect Special Relativity. Under General Relativity, which allows a wider range of metrics, both models are perfectly valid and consistent. I will disregard the effects of gravity, but otherwise it should be a pretty accurate description, certainly enough to explain what "space itself" really means.
If you define distances, times and speeds using the common sense definitions from Special Relativity (using beams of light to measure distances, always assuming a constant speed of light), distant galaxies are traveling away from us at high speeds (but less than the speed of light) and therefore time passes more slowly for them. Since this has been the case ever since the big bang, they are younger than us at this point in time. They don't just look younger because we had to wait for their light to get here, but they really are younger "right now" even if we take the traveling time of light into account. If we could "look" at them directly without having to wait for the light to get here, like we could do in a mathematical model, we would "see" the universe getting younger and younger, and clocks ticking ever more slowly, the further out we "look" in our expanding universe. At a distance of c times the age of the universe, the big bang is happening "right now". This gives the universe a finite size (assuming nothing existed before the big bang) but it does contain an infinite amount of matter thanks to Lorentz contraction. Everything near the boundary is squished in the direction of the expansion so that an infinite amount of stuff fits in this finite amount of space.
This metric is a bit cumbersome because it gives us a special position at the center of the universe while in fact there's nothing special about our position at all. Some other, distant civilisation (in the distant future according to the above metric) will actually say that we don't exist yet and our galaxy is much younger than theirs, "now". (Using their definition of "now"). That's just the classic twin paradox, nothing really wrong with that, but it does make our point of view a bit subjective.
So cosmologists came up with a better metric, the cosmological model: they define time as whatever is measured by local clocks that are traveling at the same speed as the average galaxy in that area (the expansion speed vector), undoing time dilation due to the expansion and thereby making the whole universe the same age. Local distances are defined in such a way that objects look pretty much the same size everywhere (no Lorentz contraction due to expansion speed), which can be achieved by defining distances in function of a constant speed of light relative to the expanding universe. So in effect we stretched the universe and sped it up, just by using a different definition of "now" and by measuring distances differently. With this model, the universe looks nicely homogenous and truly infinite, making many calculations a lot easier. There's no longer anything special about our location.
But because we changed our definitions of space and time, some of the old assumptions from special relativity are no longer valid. Things can and do fly away from us at speeds well in excess of the speed of light simply because we are defining their speed differently. But the light from those places will ne
That would be everyone.
Required reading for internet skeptics
... and write. All Flash memory only works because of the the tunnel effect.
You basically have a "cell" isolated from the other conductors and by adding a electrical field you can either push or pull electrons into that cell. The isolator between the cell and the conductor is a bit too big for the electrons to actually get or leave there, but with the additional field, the barrier becomes tunelable.
If you now measure your current in the conductor you can determine if there are electrons in the cell or not (as they also have a field that interacts with the flow of electrons in the conductor next to it).
Its not. Its a stupid laymen interpretation of tunneling. Try and sent information and it doesn't work because of the probabilistic nature of tunneling.
If information wants to be free, why does my internet connection cost so much?
So in other words not faster than light. I mean light in a vacuum goes faster than light in water....
If information wants to be free, why does my internet connection cost so much?
Except a "theory" is the top of the food chain in having already been proven right. There is no state higher on the path to being a fact.
So yes, the only remaining option after being shown to be correct 100% of the time each and every time, is to be proven wrong.
Problems with c? Try this one weird trick found by a single physicist!
Is it possible the author is confusing the simultaneity of quantum entanglement with "traveling faster than light" here? Hard to know since no one can RTFP.
-- sudon't
Air-ride Equipped
And no doubt their first application will be used to improve governmental surveillance systems.
It's all fine by me, as long as it runs openSUSE.
warp even the most basic rules of physics
Now that is a meaningless phrase if I ever saw one. Could someone explain what the fuck was the submitter thinking while writing this nonsense?
A successful API design takes a mixture of software design and pedagogy.
Since Einstein hasn't been proven right
Probably because you can never prove a scientific theory right. You can however repeatedly fail to prove it wrong, and that's been done many many times w/ Einstein's theories.
Unfortunately these threads have degenerated into YASSS (yet another Slashdot science seminar), where a few insightful or useful comments are made, and everyone else is trying to prove they remember or misremember their freshman physics. There has been almost no discussion of the tunneling device, which is a shame because I'd love to hear from people who have a better understanding than me.
Oh that's why F=G(m1*m2)/r^2 has the "speed limit" of 'c' in it. Oh wait it doesn't.
http://en.wikipedia.org/wiki/Newton's_law_of_universal_gravitation
Oh that is why Gravity is capped by the "speed limit" of 'c'. Oh wait it doesn't.
http://metaresearch.org/cosmology/speed_of_gravity.asp
That's why we can measure the speed of gravity with light. Oh wait we can't.
"Propagation Speed of Gravity and the Relativistic Time Delay"
http://iopscience.iop.org/0004-637X/590/2/683/fulltext/57516.text.html
You are ignorant. period.
Simple:
- Statistics: forever
- Economics: never had any real worth
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
Oh, it decidedly can. I was imprecise: The question is whether tunneling can transport information FTL.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
He said that rigid poles don't exist. They are in fact atoms which interact more or less like a chain of car suspension systems. Imagine your pole as a line of metal balls chained by a spring. When you push a ball at one end, you get a delay until it moves at the other end. With a long enought pole you need a distributed parameters model to solve the math. (The equivalent issue happens with an electric transmission line). The end result is the same as with an electric transmission line.
Here is a paper.
I'm not sure I believe the GP post's "virtual particles" theory, but - if I understand it correctly - the virtual particles would act as a sort of friction, keeping things from going too fast.
My main problem is with the earlier claim of "light speed is just an average speed." If that were true, we should measure light moving a little faster than c and a little slower than c, all averaging out to c. Instead, every measurement we take says that light in a vacuum travels at 299,792,458 m/s.
My sci-fi novel, Ghost Thief, is now available from Amazon.com.
Over what distance were those measurements made? Probably many, many meters while the slight variations from the average would probably only occur on the scale of nanometers. No contradiction there. (Although it remains to be seen whether it's true).
But what you say about friction: why would this friction be greater if the observer happens to be going in the opposite direction? Why would two different observers, measuring the same beam of light while themselves having different speeds, measure different amounts of friction working on that light beam, resulting in a measurement of exactly the same speed relative to their moving selves? That just wouldn't make sense. In relativity, the speed of light is tied to the structure of space-time itself, it's simply a maximum speed, not just for light, but also for gravity (is that affected by this friction as well, to exactly the same degree as well?!) and anything else.
What you said violates the principle you stated, i.e. no information can travel faster than the speed of light. But a shadow could be used like a signalling device...
Indeed a shadow could be used as a signalling device but only from the object creating the shadow to the surface on which the shadow lies NOT between two points on the surface where the shadow lies. Same with the torch/laser: it communicates information from the earth to the moon NOT between two points on the moon (unless they signal the earth and then the earth signals back to the moon which, of course, will not be faster than light).
http://fhs-consulting.com/aa1tj/Bobik.html - Bobik; An 80m tunnel diode transmitter that spanned over 1000km its first night out!
http://fhs-consulting.com/aa1tj/mikums.html - Mikums; A one-tunnel diode, 80m transceiver
http://fhs-consulting.com/aa1tj/tunneldiodetransmitter.html - Tunnel Diode Transmitter; An adventure with two dots of dirty Germanium
http://fhs-consulting.com/aa1tj/TDConverter.djvu - Tunnel Diode Converter Circuits; Article by Erich Gottlieb
FTL wouldn't cause any problems with causality at all but a lot of other theories would have to go.
Correct - the theory you are wanting to get rid of is Special Relativity. This is the most precisely tested scientific theory there has ever been and not only is there no indication whatsoever of it being wrong but it is known that tunnelling does not carry information faster than light.
The electron stops probably being at one place and becomes more probably in another place.
Well, there was a probability of it being in both places the entire time. Tunneling just means that its probability function spans a region that it couldn't exist in otherwise.
It's not really that profound of a process, but just like semiconductor bandgaps, it can be engineered to be useful to us.
If you want a vision of the future, imagine a youtube comments section scrolling - forever.
For example you construct a wormhole and transmit a message thru it from earth to mars.
Possibly correct (needs negative mass!) but it would not violate causality. It would be impossible for someone to stop the message being sent unless they were in the wormhole hence, even if in their frame the events happen in reverse order, it is not possible to violate causality from outside the wormhole.
You are making an assumption that such frames would need to exist. We don't really know if this is true at all.
Yes we do - basic first year relativity. If two events are causally connected i.e. event A causes event B then you can easily show that if the speed of information propagation between them exceeds 'c' you can construct a valid, inertial frame where the order of events is reversed. Go look at the relativity chapter in any first year university text book and there will be a section on proving this - at least it has been in all the text books I've used for teaching first year calculus based intro physics courses.
"Nope. The motion propagates to the far end at the speed of sound in the pole"
I think they are referring to actually moving the pole. As in, push and pull (on/off). Are you suggesting that one end would not move at the same time as the other end?
That's correct. The push and pull would propagate through the pole at the speed of sound. You don't see this with short poles (ie in real life) because the poles are small and the speed of sound is relatively high in solids.
If you want a vision of the future, imagine a youtube comments section scrolling - forever.
All open and unresolved problems are not necessarily equivalent. If they were, solving any one of them would provably lead to solving them all.
File under 'M' for 'Manic ranting'
Why would it?
The atoms in the material are not "conjoined", there are no solid things pushing against each other. They are point forces that act upon each other. The closer they are, the more they will "push" away the other, like atomic springs. But they aren't touching to begin with, merely held in a nice "valley" of forces where they can rest naturally in a particular material. In a dense material, that valley is probably closer to other atoms than in a less dense one but at no point are the protons from one atom hitting those of another (or else you could start a nuclear reaction by banging two things together or putting Uranium under pressure by - say - burying it under a million tons of rock).
Shoving one end of a pole six feet long might only take some infinitesimal fraction of a second to see the effect on another but it doesn't mean it was instantaneous.
Imagine you had a box full of rubber balls. Now imagine you push the bottom of the box up. Are you suggesting that the top rubber ball responds instantly at the same rate at the force at the bottom? Or that the force you applied compresses the bonds between atoms that push each other away, and so that pushes on the next, and that, eventually, when it reaches a point where it can't be compressed any more, pushes on the next and on the next and so on. It's a physical chain of events, not magic.
Then, are you suggesting that happens instantly in any material that isn't a material at absolute zero of the highest possibly achievable density? Because Brownian motions mean that the atoms are pushing off each other all the time but still they "react" instantaneously? No.
Think of a tube of Smarties (a small tube of sweets). When you push the bottom of it the top one drops out but that isn't "movement" of that one across the whole distance of the tube. And it's not instantaneous.
And if you scaled it up, shoved it with a huge stick and filmed it in slow motion, are you suggesting that you would not see the smarties compress and distort and fight the force for a fraction of a second before they poured out of the other end? Now think of atoms as smarties and see what happens.
By applying a force, no matter how small, to an solid object you are STILL compressing that object's atoms to be in closer proximity But they are NOT touching (think about electron orbitals, etc. - if they could touch you have MUCH bigger problems, like electrons being trapped and held still). The "movement" of that object as a whole is the resulting actions of those atoms while still caught within the atomic bonds that they are.
The atom is also mostly vacuum. The forces within it are what make you think it's "solid". It's not. Those forces can be added to from any direction and the result is NOT that the molecules of atoms move in that direction automatically. It might compress, bringing the atoms closer, but then they fight each other back. Hence we *can* turn carbon into diamonds when the carbon atoms are compressed and forced into a certain state. And we can "break" an atom by firing something and powerful direct at its nucleus.
The atom is not solid. As a result, no solid material is "solid". They can all be compressed with the application of force except for a material at the maximum possible density at absolute zero (the heat is enough to make the material have a force to fight back). As they can be compressed a lot, they can also be compressed a tiny, infinitesimal amount on a sliding scale. And the gaps between them are not solid-steel-girders of reinforcement but the forces at play (similar to a magnetised ball-bearing near another, oppositely-magnetised ball-bearing) that can be overcome up to a point.
And by pushing on the bottom of a pole, you are putting an atom with a certain force near another atom with another force and pushing them into proximity. If it's easier for that atom of the pole to push you back, the object doesn't move and your hand stops. If it's not, it will push it's neighbour the
The "signal" represented is psi squared, or the probability of finding the particle at a particular position in space. The particle can exist anywhere under that curve. With an energetic enough particle or a small enough potential barrier, the particle can predictable tunnel across the barrier, which is what the video is showing (The video is showing the probability of the particle tunneling).
The tunneling process itself depends on collapsing the wavefunction and the particle interacting with some other physical process. Collapsing the wavefunction is an instantaneous "event". Any time the probability function spans both sides of the potential barrier, there is a chance that the particle can "exist" on either side of the barrier. In this case, it never crossed the barrier, because it always had a chance of existing on both sides of it.
If you want a vision of the future, imagine a youtube comments section scrolling - forever.
Yep, that's pretty much the hard argument for what I said. Keeping in mind that light doesn't give a north end of a southbound rat how we define anything. Of course, since that light never reaches us, its existence is wholly theoretical, but I just go with the last semi-sane thing I hear from a cosmologist. :)
I've fallen off your lawn, and I can't get up.
carry information.
The Kruger Dunning explains most post on
Yet another industry article on a potential replacement for silcion transistor technology. Hundereds if not thousands of these in the past decades. Less than one percent of these technologies see commercial success. But we got to keep trying because the rewards could be immense.
8-PP
". It may even be able to transfer information, but the jury is still out on that and classical quantum mechanics says it cannot."
as do all tests. The Jury isn't out. This is science. There is no vote, there is no Jury. No test to date have had any indication it can carry information.
The Kruger Dunning explains most post on
You're PhD in Statistics is no longer relevant the moment you can't use statistics to prove your relevancy.
You're economic PhD is no longer relevant when you run out of hands
The Kruger Dunning explains most post on
Spoken like an idiot.
The Kruger Dunning explains most post on
Along with the furnaces and the iron ore deposits?
No, I'm afraid it was East Africans who first actually smelted iron.
The world's burning. Moped Jesus spotted on I50. Details at 11.
but Gunter Nimtz has used microwave tunneling to send information fast than light, and his experiments have been replicated.
Many researchers are complaining, they don't like the results.
...contained in circuits that warp even the most basic rules of physics.
Well if the laws of physics are getting broken (or "warped") by reality, then they can't very well be the laws of physics. The *laws* of physics, by definition, apply universally. Maybe the headline should be "New circuits might work using well studied quantum effects that are not part of the simplified, 19th century version of physics taught in American high schools"
You wish.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
You are quite right. Light, or anything else in the universe, indeed doesn't care what coordinate system we use. The end result will still be the same, you can't calculate with one reference system that we will see something while another system says we won't. Or that two things will hit each other in one system and not in the other. But for things that are not directly observable, or vague numbers that don't physically mean anything ("How far is it? When did it get there? Does it even exist if we will never see it?"), you'll get wildly different answers. And you can't even say that one system is better than the other. Coordinate systems are just (flawed) tools for us to try and calculate things. It's all in our head, really. Physics doesn't care.
I think it's useful, though, to realise what's really happening, and where this "cosmic conveyor belt" is coming from. Many people seem to think that it's some kind of aether, influencing the speed of light. But it's really just us using math to undo the funky effects of relativity and, surprise, creating contradications with special relativity in the process. Which we then explain by assigning properties to "space itself". The day I figured that out, it was quite an epiphany for me.
There are other places where different metrics are being used: black holes, for example. That's another area where you can't really pick one true coordinate system. In fact, you might even say black holes don't exist and never will, because local time slows down to an asymptotic standstill before the last drop of matter falls in to complete the black hole. All we have is near-black-holes. But switch to a different coordinate system and there they are. They do exist after all, "right now". And then there's a choice of different metrics to describe the inside of them, the Schwarzschild metric being the most well-known but certainly not the only one. Time can stop, go backward, go imaginary, you name it. It's just us forcing physics into a badly fitting mathematical suit.
Tunneling is instantaneous.
No. Tunneling is caused by the leakage of the wavefunction through a barrier, which is a gradual, continuous process. Some interpretations of quantum mechanics claim that the collapse of the wavefunction (the point where it goes from being partly on each side of the barrier to being entirely on one side) is instantaneous. But that's very controversial, and many other interpretations disagree. But tunneling itself - the uncontroversial, well established phenomenon - is very definitely continuous and non-instantaneous.
"I'm too busy to research this and form an educated opinion, but I do have time to tell everyone my uninformed opinion."
What you are describing is the Copenhagen interpretation of quantum mechanics, which is not universally accepted, and in fact has been steadily decreasing in popularity for decades. At one point it was accepted as the "conventional wisdom", mainly because there wasn't any better alternative, but that was a very long time ago. Today we have lots of better alternatives, and at least among people who actively study interpretations of quantum mechanics, it is not widely believed anymore.
"I'm too busy to research this and form an educated opinion, but I do have time to tell everyone my uninformed opinion."
Anyone care to elaborate on this ? I've spent countless sleepless nights pondering how a framework could manifest itself without interaction from matter or energy.
Flourescent (adj): smelling like ground wheat.
The ad hominem character and emotional fervor in the responses to this post perfectly illustrate the religious nature of the current scientific dogma!
You're right that the plot is of the absolute square of the wavefunction, not the wavefunction itself. That wavefunction is what the particle actually is - it contains all the physically relevant information about the particle. But even with your interpretation of it, I think you are being inconsistent. You admit that the wavefunction itself takes time to cross the barrier, so what do you mean by the particle instantaneously tunneling? Are you imagining a situation where you first measure the position of the particle, and find it to be on the left side, and immediately measure it again, and find it to be on the right side, with no time in between. That would qualify as instantaneous motion, but that will not happen. After the first measurement, the wave function will be concentrated on the left side of the barrier, and for part of it to move through the barrier, you have to wait at least long enough for light to pass it. If you try measuring the position of the particle before that, you will have a 0% chance of finding it on the right side.
PS: Most of your argument does not seem to have anything particular to do with tunneling, and would work for any extended wave function. So aren't you also saying that you can get superluminal motion anywhere at any time? It is not difficult to prepare a wave function that has a significant amplitude over large areas.
That's what I like about physics. :) (contrariwise, it's what makes me suspicious of quantum physics...)
Have you run into the "proof" of determinism demonstrated by showing that a viewpoint across an interval where the object being viewed is on an (I believe) approaching vector near lightspeed) results in viewing that object in the future, thereby assuring us of the fixed sequence of events that will lead to that view? I may have that a little jumbled, the idea had me dizzy for days.
Nova had some dumbed-down cosmological thing on where they diagrammed that out. I had to go listen to some Pink Floyd afterwards, lol.
I've fallen off your lawn, and I can't get up.
That's not really a proof of determinism, but I know what you mean. Just by moving forward and backward a bit, I can make, say, the Andromeda nebula go back and forth in time by a few hours. A local civilisation may have just decided to invade us, but then go back in time to the point where the decision still has to be made. But obviously there can be no uncertainty about their future decision, since we already know what it is.
Only... we don't actually know what it is. All we can say is that the decision might or might not have been taken depending on what time coordinates we assign to the event, but we'll still have to wait for their signals to get here at the speed of light before we could possibly know what the decision was/will be. So things are just as uncertain whether they have "happened" or not. And we cannot influence them in any way, so it's really meaningless to say whether they happened in the past or the future.
The solution, I think, is to forget about our old-fashioned notion of simultaneity. Our clock has nothing to do with their clock. Just because we happen to change our time coordinates, doesn't mean that something "happens" over there. All events just go their own way in their local part of the universe, independently, and interact at the speed of light. There's no "now", except locally. Events over there may be happening just as randomly as over here, and it's meaningless to think about whether they happened earlier or later. They will only influence us in the far future in either case, and by then the decision certainly will have been taken.
Detemininism means that, knowing the initial conditions, you would be able to predict the outcome. That only really works locally: you can predict what you will observe. You can't predict "something will happen over there" but you might predict "I will observe the fact that something will have happened over there".
The decision in the Andromeda nebula is made when the local events get to that point, and then repercussions from that event radiate outward at maximum the speed of light (which takes more or less time depending on the observer), until they reach us. The event doesn't physically have time coordinates, it just does its thing. We might assign it some present, future or past time coordinate but that doesn't change the flow of things. Things just happen, without any reference to anybody's clock, and the fabric of space-time will allow us to come into contact with that separate flow of events some time in the future. At no point is the flow of events really reversed.
Or in yet another way, every tiny particle has its own clock and those clocks have nothing do do with each other. They can interact when they happen to reach the same place, but are otherwise independent.
Not sure I'm making any sense, it seems somehow clear to me but I'm having trouble communicating it.
Yeah, I read that three times and my head is still spinning.
That's pretty much what happened the first time, too. Just doesn't want to sink in. I don't have the background to really comprehend this at the right level; just local physics instincts, and they often seem to come up short when cosmology is the subject at hand.
I would love to go over a couple things with you via email, if you felt you could spare the time. I'm at gmail, same handle. If not, no sweat, of course. Cheers!
I've fallen off your lawn, and I can't get up.
Q: What's the difference between a quantum mechanic and an auto mechanic?
A: A quantum mechanic can get his car into the garage without opening the door.
Note: When I thought that joke up over 35 years ago, there was little risk that "Auto mechanic" would be misconstrued as referring to an autonomous programmed agent, except in Science Fiction.
PS: Most of your argument does not seem to have anything particular to do with tunneling, and would work for any extended wave function.
My argument sounds like that because that is my point. There's nothing particularly special about tunneling. Once the probability function spans the barrier, the particle is capable of existing on either side. There's no superluminal motion involved at all. Of course, the wavefunction itself can only travel at a finite speed (much less than c, we're talking about an electron in this case), but once it spans the barrier, the tunneling process itself is instantaneous.
If you want a vision of the future, imagine a youtube comments section scrolling - forever.
Did you read the rest of my comment, other than my postscript? What exactly do you mean by it being instantaneous? How could one measure this? Could you explain in detailed, small steps how you think the tunneling works, and which of those steps is instantaneous?
This discussion is really starting to bore me and I'm apparently doing a poor job of explaining myself. Read the literature yourself; this is a very thoroughly discussed issue. I imagine the misunderstanding comes down to some semantic mismatch, but I'm not interested in locating it.
Cheers,
If you want a vision of the future, imagine a youtube comments section scrolling - forever.
Fair enough. For what it's worth, I had a look through the literature now, and I see that this is a much more controversial issue than I thought, and the result seems to hinge upon exactly how one measures the tunneling time.