Hard Light Productions Forums
Off-Topic Discussion => General Discussion => Topic started by: FUBAR-BDHR on September 26, 2013, 12:53:33 pm
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http://www.cnn.com/2013/09/26/us/new-lightsaber-molecule/index.html?hpt=hp_t3
Looks like light matter is not longer theoretical......
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So basically, the MIT created... Hard Light?
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da wuq
will comment later if I understand anything about it, however first impression is that this is a science related news published by major news agency rather than scientific publication -> reliability can be anywhere between 0 and 1
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So basically, the MIT created... Hard Light?
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I thought Lightsabers were contained streams of plasma....
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fut
da wuq
Will wait for Herra's assessment, but at first blush this is some crazy stuff.
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Well, I'll just say this - if they really managed to get actual photons to interact with each other to form molecule-like structures (and we're talking about bosons here, not fermions) that's really rather... interesting. You know, all that stuff with fermions being characterized by Fermi-Dirac statistics and bosons following the Bose-Einstein statistic, fermions having half-spins and bosons having integer spins, little things like that.
Photons in general always move in vacuum at speed of light and that really precludes them from actually interacting with each other or anything else except the space-time that they travel though. Physical characteristics of different media can "slow down" light if you're handling it as EM radiation - in which case it still doesn't affect the speeds of individual photons but rather the collective velocity of the wave front.
I'm not really sure how literally I should be taking this article; I'm pretty sure the whole thing is more about some crazy weird interference of light traveling in a media where it's velocity is very slow, rather than individual photons forming any kind of "bonds" with each other. It's still interesting but I can't really take it on face value until I read something that actually makes sense.
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Well, from what I've gathered from the article, they've gotten an immensely interesting quantum effect of some sort in a Bose-Einstein condensate. I'd like to see a more scientific publication on that matter, this obviously is a breakthrough, but the article oversimplifies it so much it hurts. Perhaps I should finally subscribe to "Nature". :) I don't think it's the same "slowdown" effect that gives us Cherenkov radiation (though it's probably related), rather, it's something completely new, and quite intriguing.
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Original paper (http://www.nature.com/nature/journal/vaop/ncurrent/full/nature12512.html)
Interesting stuff, albeit beyond my comprehension. Sounds less like 'molecules of light' and more like the photons are only behaving as if they are bonded due to the way they are interacting with the atoms in the medium.
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Well, that's quite impressive. Shame "Nature" only allows limited access and charges 200$ for subscription (which, unfortunately, is a lot around here). I'm tempted to purchase just this particular article, though perhaps I could access it through my university's library. This indeed is an important breakthrough, but rather than lightsabers, this seems more connected with quantum teleportation research and quantum computing. This is a completely new form of matter/energy (well, there's hardly a difference in such conditions) and certainly really interesting.
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erm, should I go get this and uh, certainly not post it, but
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Slowing down photons and they started to behave like matter bumping into atoms, even photons bonding to each other to form molecules. Reminds me more of replicators and transporters than light sabers.
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Another Step? Don't tell me SFX in Hollywood counts as the first.
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Another Step? Don't tell me SFX in Hollywood counts as the first.
Hey, take a look at Star Trek
They were the first to bring up the concept and idea of some pretty nifty things before they were actually possible
People probably wouldn't of thought about those ideas if it weren't for them
So yeah
Coming up with the idea of something is the first step
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Another Step? Don't tell me SFX in Hollywood counts as the first.
Hey, take a look at Star Trek
They were the first to bring up the concept and idea of some pretty nifty things before they were actually possible
People probably wouldn't of thought about those ideas if it weren't for them thinking of those ideas.
I know what you're trying to say, but I just couldn't resist. :P
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Another Step? Don't tell me SFX in Hollywood counts as the first.
Hey, take a look at Star Trek
They were the first to bring up the concept and idea of some pretty nifty things before they were actually possible
People probably wouldn't of thought about those ideas if it weren't for them thinking of those ideas.
I know what you're trying to say, but I just couldn't resist. :P
Oh hey you bolded it!
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Why would anyone build a lightsaber is still a mystery to me (other than rule of cool).
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To win the most awesome Darwin Award, ever. :yes:
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To win the most awesome Darwin Award, ever. :yes:
You know someone's going to get the saber mini and achieve death when attempting to shave off neckbeard and gonad hair for bikini season.
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Lightsaber would be invaluable in its capacity of cutting through pretty much anything. Using it as a sword... Why? Projectile weapons are easier and more efficient. If you want close up, silent assassination, use a regular blade, so the darn hum of the Lightsaber won't give you away.
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Wouldn't blaster weapons be based on the same technology? Pew pew and all that.
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Nope, they're pretty much plasma throwers. Completely different, presumably magnetic bottle-based. That said, this discovery would have more influence on teleportation research than on cutting tools of any sort. There exists a much better, plasma blade-based lightsaber concept, which seems more practical than using light matter for this.
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Well, even if they did get light to interact with itself to form structures, that doesn't mean those structures would, as such, interact as physical objects. They're still made of light, and would only interact with matter like any light would - give it enough intensity and it'll burn through, but it won't really knock things around like a physical blade would.
Apart from the fact that it's, you know, confined to the really cold matter that makes it slow down enough to form said "structures" in the first place - I suppose you could knock someone around with a super cold piece of equipment, but I believe the light would be the least important factor in the damage caused.
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I mentioned this earlier, but in canon the lightsaber is a plasma weapon. Although they do put precious stones in them.... Bah.
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http://starwars.wikia.com/wiki/Lightsaber
It's canonically a plasma blade. I've found no mention of "light matter" on Wookiepedia. There aren't too many details on the tech, but somewhere I've read a description of a magnetic bottle-based loop that would enable a lightsaber-like appearance. Also, an extending rod projecting plasma could be used, but it'd not sit well with canon (that said, SW does have lightsabers with a sold core).
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Woah woah, slow down.
Allow me to play the layman and ask:
Doesn't light already bounce into matter? Is that not how mirrors work?
Anyway, this seems to venture more towards the path of holograms than lightsabers...
In such a case, we may need to patent the name "Hard Light Productions" ;7
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You're misunderstanding the whole thing. Holograms and mirrors are about altering the direction the light is moving in. This is about altering it's speed, to the point of stopping it. And very interesting things that happen afterwards. This is mostly related to quantum research, quantum computing and teleportation.
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How can it lead to teleportation?
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Well, this all contributes to our understanding of quantum effects. Quantum bonds, like ones created in this experiment, are fundamental to any serious approach to teleportation. Under certain conditions, it might be possible to use quantum entanglement to transfer information faster than light. In short, better understanding of them is very important to this kind of research. A longer answer is also possible, but it gets very technical and I don't think my explanation would be quite up to task. Indeed, it would probably take one of the best university lecturers to explain this to a complete layperson in a way that doesn't boggle his/her mind. This subject, while interesting, is a very though one, and riddled with complex mathematics to boot. Check out books by Michio Kaku, if you want to know more, he's very good at explaining complex things like that in accessible terms. While he probably didn't write anything about this particular experiment yet, if you read his description of teleportation research, it might become clearer why there is a connection.
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No it "might" not be possible to move information faster than the speed of light. This is mostly known in the physics community and entirely misunderstood in the layman "informed" community.
The reason why teleportation will always be "as fast" as light speed is because you cannot ever confirm you got the teleported data without an external confirmation of itself, which always comes in the form of light (for example). All the other cases where you go faster than light are also nonsense, like the Alcubierre drive and so on. It's a real shame, but it just isn't possible to do those kinds of things. The reason is very simple to understand though: while in theory you can bend space (and thus you can turn what is a light year space into a light minute space) you must do so with gravitational waves.... that transverse spacetime at the speed of light!
To allow beyond lightspeed travel would create all sorts of impossibilities, the more well known and understood would be time-travel paradoxes.
So no, AFAWK, FTL speeds are indeed impossible.
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Yeah, the whole Alcubierre drive thing is pretty dumb. Gravity and presumably any change to the curvature of space can only propagate at the speed of light. So you can't use it to speed up the trip to anywhere you haven't been. Portals maybe, warp drives no.
IMO the NASA guy who's trying to make an Alcubierre drive should be defunded immediately.
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Yeah, the whole Alcubierre drive thing is pretty dumb. Gravity and presumably any change to the curvature of space can only propagate at the speed of light. So you can't use it to speed up the trip to anywhere you haven't been. Portals maybe, warp drives no.
IMO the NASA guy who's trying to make an Alcubierre drive should be defunded immediately.
A. We don't know that space-time disturbances propagate at speed of light, because we have never empirically detected gravity waves and confirmed their origin synced with some major observable event whose distance we know. It's good speculation, and probably that's how it works, but we don't exactly know it.
B. Space between two objects can expand at a rate that distances the two objects regardless of speed of light.
C. Alcubierre drive works by expanding space behind ship and contracting ship in front of it.
D. Historically, do you have any idea how many scientific breakthrough discoveries were predicted to result from this or that research study or experiment?
Almost none. Vast majority of BIG scientific discoveries have been accidents, byproducts, sometimes even ignored as unimportant or thought of as mistakes. The path of scientific progression is unpredictable at its most boring times and wildly random at the interesting times.
This is why it's a bad idea to try to "direct" scientific research into "profitable" or "promising" subjects. Anything and everything should be researched; basic research is probably the single most important thing to keep science advancing.
Granted, in this particular case they're definitely consciously trying to complete a major scientific and engineering breakthrough, one that - if successful - will possibly be spoken of as the beginning of a new era. It is an incredibly ambitious undertaking, and I'll be the first to be skeptical about their goal of success.
Regardless of this, though - I firmly assert that de-funding this research or any other on the premise of not being profitable or being impossible is foolish and unscientific.
Maybe they won't succeed. But what if they would, but their funding was cut before they managed to get it working...
E. Even if they don't succeed in fulfilling their exact goal, they'll be dealing with a lot of uncharted, unknown territory. What makes you think the research could not produce other, unforeseen results?
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Nah, they measured gravity somehow and found it propagated at between 0.8x and 1.2x the speed of light.[citation needed]
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No it "might" not be possible to move information faster than the speed of light. This is mostly known in the physics community and entirely misunderstood in the layman "informed" community.
The reason why teleportation will always be "as fast" as light speed is because you cannot ever confirm you got the teleported data without an external confirmation of itself, which always comes in the form of light (for example). All the other cases where you go faster than light are also nonsense, like the Alcubierre drive and so on. It's a real shame, but it just isn't possible to do those kinds of things. The reason is very simple to understand though: while in theory you can bend space (and thus you can turn what is a light year space into a light minute space) you must do so with gravitational waves.... that transverse spacetime at the speed of light!
To allow beyond lightspeed travel would create all sorts of impossibilities, the more well known and understood would be time-travel paradoxes.
So no, AFAWK, FTL speeds are indeed impossible.
You missed one important point in my post. I wasn't talking about Alcubierre drives, or indeed, anything associated with gravity. I was talking about quantum entanglement (http://en.wikipedia.org/wiki/Quantum_entanglement). It's been experimentally proven that this occurs, and it works "faster than light". The question is if you can actually transmit something using this effect. Nothing really "travels" in that case, aside from information, which could possibly be used for teleporting objects. Of course, it would be not very useful for space exploration, because you need a receiver which was, at some point, in contact with the transmitter. But still, it's an important and very interesting area of research.
Also, space can expand faster than light. Otherwise, the Great Expansion after the Big Bang wouldn't have been possible. Alcubierre drive is an unlikely tech, because it involves literally re-shaping the universe to your liking. In layman's terms, instead of moving an object, you're moving the place this object is in to somewhere else. The energies involves, as well as the physics of it are rather crazy, but it might be possible under some theories (there's no confirmation on that, but that's what experimental physics are for).
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For god's sake Dragon you are not the only one who understands things.
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Fool!
This is HLP! Every single one of us is the only one who understands things and we must explain that to everyone else, at every opportunity, in the most condescending way possible. How else will they learn? How else can we assert the colossal size of our e-peens egos intellects?
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its still 93% less derp than the ksp forum.
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Dragon seems to be being nice and helpful to me...
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Dragon, I missed zero in your post. Of course I was speaking about entanglement when I mentioned that you cannot have data transferred faster than light. The reason, as I stated previously, is that this "teleported data" is not readable and confirmable until you get external sublight confirmation that indeed the data is read correctly. It is more complex than this, but rest assured, the light barrier is still king. This effect cannot produce the Mass Effect communication device.
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Nah, they measured gravity somehow and found it propagated at between 0.8x and 1.2x the speed of light.[citation needed]
Now you're giving error bars. I'm aware of the experiment(s) you refer to, although there's been some controversy about what they actually measured, if I recall correctly (it's possible that they simply ended up measuring the speed of light in a slightly novel way). There is no strong consensus about what the results of their measurements mean and how they should be interpreted.
General relativity does predict that speed of gravity would be exactly c, I was merely pointing out that we haven't so far been able to empirically measure it in a clear, non-controversial manner. Such as detecting a known gravity wave front on one side of Earth and then detecting the same gravity front on the other side of Earth some parts of second afterwards. The two measurements could then be synced by recognizing the profile, and comparing the arrival times should show fairly clearly what the speed of gravity is; the problem is making sensitive enough instruments to observe these small changes in space-time.
Honestly speaking I do expect space-time changes to propagate at c, it would make quite perfect sense regarding why speed of light is the ultimate limit of traveling through space-time in any reference frame. That said, this seems to be specifically irrelevant considering the Alcubierre drive which is basically a solution of the general relativity equations that allows moving at higher than speed of light without exceeding speed of light relative to local space-time.
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Dragon, I missed zero in your post. Of course I was speaking about entanglement when I mentioned that you cannot have data transferred faster than light. The reason, as I stated previously, is that this "teleported data" is not readable and confirmable until you get external sublight confirmation that indeed the data is read correctly. It is more complex than this, but rest assured, the light barrier is still king. This effect cannot produce the Mass Effect communication device.
Can you define "correctly?" You either receive the data or you don't - isn't the order or interpretation of the data handled by the design aspect of such a device?
I mean...for a human being to receive data, you just need to have a sublight emission happening at the point of reception for this teleported data.
Or, whatever. Maybe this really is just way over my head. :doubt:
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Basically, if you have a pair of particles that are entangled (http://en.wikipedia.org/wiki/Spooky_action_at_a_distance), their quantum states are tied to each other. This means that, if you conduct a measurement on one and observe a certain state value, the other particle will always take on the corresponding opposite state value. The crazy part is that this effect happens faster than the speed of light could have conveyed information between the two particles...in fact, it's (theoretically at least) an instantaneous process.
Now on the surface, this seems like we could use this phenomenon in order to send faster-than-light messages, but here's the catch: there's no way to actually deliver useful information with it. Let's say that a person at point A measures the first particle, and then a person at point B measures the second and observes the opposite value. From the perspective of the person at point B, they have no idea whether what they saw was the result of the corresponding measurement at point A, or if their own measurement was first and collapsed the particle's wavefunction down to that state. There's absolutely no way to tell the difference, other than the person at point A sending a message saying when they observed their particle and what they saw. And since that message would be, at the very fastest, bound to the speed of light, information can't possibly travel any faster using this method.
Hopefully that makes things a bit clearer, though when you're dealing with quantum stuff, there's only so clear you can really get. :p
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Note, this is currently an area of heavy research. That's why I said it "might" allow for FTL transmissions. At this point, there are a number of theories, some of which could allow such transfer. Answering that question with certainty could probably net you a Nobel Prize. The results are still inconclusive, that's precisely why this field is so interesting. That there's no way to actually transfer information through quantum entanglement at this time does not mean one wouldn't be found. The conservative viewpoint is that it's impossible, but there are others that permit it.
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Quantum entanglement would be much more useful for encryption than data transmission.
Well, and quantum computing, obviously.
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Note, this is currently an area of heavy research. That's why I said it "might" allow for FTL transmissions.
It is also an area that was studied for a long time (80 years or so?), is understood quite well with no evidence of a FTL transmission and FTL violates basic laws of physics. I wouldnt hold my breath.
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Yeah, the whole Alcubierre drive thing is pretty dumb. Gravity and presumably any change to the curvature of space can only propagate at the speed of light. So you can't use it to speed up the trip to anywhere you haven't been. Portals maybe, warp drives no.
IMO the NASA guy who's trying to make an Alcubierre drive should be defunded immediately.
The expansion and contraction properties of space time are not subject to relativistic effects. Relativity is a property of particles propagating through space. It is not a property of space time itself. Thus through expansion it was possible for information to exceed the speed of light relative to an outside observer if the universe itself is expanding faster than light.
The main problem with the Alcubierre metric (which is a solution of general relativity, by the way - it is not something invented for the fun of it) is the fact it requires a negative energy density to function and generates yottawatts of radiation at the front of the bubble.
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Note, this is currently an area of heavy research. That's why I said it "might" allow for FTL transmissions. At this point, there are a number of theories, some of which could allow such transfer. Answering that question with certainty could probably net you a Nobel Prize. The results are still inconclusive, that's precisely why this field is so interesting. That there's no way to actually transfer information through quantum entanglement at this time does not mean one wouldn't be found. The conservative viewpoint is that it's impossible, but there are others that permit it.
No, it's actually pretty conclusively not possible.
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Note, this is currently an area of heavy research. That's why I said it "might" allow for FTL transmissions. At this point, there are a number of theories, some of which could allow such transfer. Answering that question with certainty could probably net you a Nobel Prize. The results are still inconclusive, that's precisely why this field is so interesting. That there's no way to actually transfer information through quantum entanglement at this time does not mean one wouldn't be found. The conservative viewpoint is that it's impossible, but there are others that permit it.
No, it's actually pretty conclusively not possible.
I don't think "pretty conclusively" means "disproven beyond any reasonable doubt". :P
Maybe splitting hairs here, but hey. Science.
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Well, even if they did get light to interact with itself to form structures, that doesn't mean those structures would, as such, interact as physical objects. They're still made of light, and would only interact with matter like any light would - give it enough intensity and it'll burn through, but it won't really knock things around like a physical blade would.
Apart from the fact that it's, you know, confined to the really cold matter that makes it slow down enough to form said "structures" in the first place - I suppose you could knock someone around with a super cold piece of equipment, but I believe the light would be the least important factor in the damage caused.
Well, they did say the photons slowed down, bounced off of other molecules, and formed with other slowed down photons to form molecules. That i think is very telling of what happened. That's why i said earlier, screw lightsabers, let's think about teleporters and replicators. This is what i think this actually applies to.
It's easy to directly convert matter to energy; campfires. It's another thing to do the opposite. Now one thing tells me if you slowed down photons to the point that they are behaving like matter, to the point that these slowed down photons have formed molecules with other slowed down photons. It gets me thinking that an energy to matter conversion actually happened. Which is why i was thinking replicators and transporters (transporters in the area of conversion of energy back to matter, not the teleportation part).
Maybe they didn't speak literal enough, but i thought the article did. These slowed down photons were no longer particles of light.
This gets into another great area of the universe. This means that light travels faster and slower in certain areas of the universe. Or that at once, light travelled slowly, then faster, perhaps kept the same speed, or perhaps light slowed down (science has yet to find this out later wth more discovery). Either way, we learn much from slowing down particles and the big bang perhaps.
The catalyst being simple, an outburst of energy in 0k.
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Note, this is currently an area of heavy research. That's why I said it "might" allow for FTL transmissions. At this point, there are a number of theories, some of which could allow such transfer. Answering that question with certainty could probably net you a Nobel Prize. The results are still inconclusive, that's precisely why this field is so interesting. That there's no way to actually transfer information through quantum entanglement at this time does not mean one wouldn't be found. The conservative viewpoint is that it's impossible, but there are others that permit it.
No, it's actually pretty conclusively not possible.
I don't think "pretty conclusively" means "disproven beyond any reasonable doubt". :P
Maybe splitting hairs here, but hey. Science.
It actually means "disproven beyond any unreasonable doubt". To allow FTL transmissions is the same as allowing FTL travel, which would all violate Lorentz symmetries (basically allowing not only FTL travel, but also time travel, and thus allowing impossible paradoxes of the father-son category). All the romantic research involving Lorentz violations have failed miserably so far (and predictably).
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It all depends on how you define "FTL".
Quantum entanglement cannot be used to transmit information because even if you have an entangled pair of particles, you can't actually measure a particle's state without changing it, and when you change one particle's state, the other particle's state also changes and you get this back and forth effect of measurement affecting the particle's state and if you try to measure it in both ends you just end up with a continuous noise of measurements on both ends changing the particle's state.
Basically, quantum entanglement is only useful if you have, like, two quantum entangled encryption keys which you then use to encrypt and decrypt messages. But if you want to compare the quantum states of the entangled particles, you need independent communication anyway to do that...
However, there's no causality problems associated with most of the "more realistic" FTL schemes.
If information goes from A to B in shorter time than t=s/c, it just means that the distance s that the information used was actually shorter than you thought. That's all.
By the way, even if it turns out Alcubierre Drive doesn't work for FTL - don't you think it would have some applications in subluminal space travel regardless?
Not needing propellant would be reasonably useful. We could also extract infinite energy from Newton's grave.
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However, there's no causality problems associated with most of the "more realistic" FTL schemes.
If information goes from A to B in shorter time than t=s/c, it just means that the distance s that the information used was actually shorter than you thought. That's all.
But then it means there was no FTL travel / communication at all, obviously.
By the way, even if it turns out Alcubierre Drive doesn't work for FTL - don't you think it would have some applications in subluminal space travel regardless?
Not needing propellant would be reasonably useful. We could also extract infinite energy from Newton's grave.
That's quite a different discussion that I'm sure engineers will discuss when they try to make it work... but I think it's quite useful to tell them what *not* to expect coming out of it, lest they have wrong expectations.
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But then it means there was no FTL travel / communication at all, obviously.
That's why I said it depends on the definition of FTL.
I think there's pretty good consensus that it isn't possible to exceed speed of light in any local reference frame - so we have to figure out a way around that obstacle, not through it.
And sometimes the route around is shorter than through.
But, for practical purposes, if Alcubierre drive allows traveling from A to B faster than distance between A to B seems to be I would call it FTL travel and be done with it.
By the way, even if it turns out Alcubierre Drive doesn't work for FTL - don't you think it would have some applications in subluminal space travel regardless?
Not needing propellant would be reasonably useful. We could also extract infinite energy from Newton's grave.
That's quite a different discussion that I'm sure engineers will discuss when they try to make it work... but I think it's quite useful to tell them what *not* to expect coming out of it, lest they have wrong expectations.
Yeah, well, the problem with uncharted territory is you don't know what's behind the next hill until you get an overhead satellite pass to give you a picture.
We have some theory-based guesses on what to expect. In theory, Alcubierre drive would for example create a hefty bit of radiation and I have really no idea how it would affect the surrounding space-time (ie. how well would the warp bubble be contained).
Practical problem currently is we have no idea how to actually make negative energy (or negative pressure) aside from Casimir effect which isn't really a demonstration of negative energy IMHO, but rather lower vacuum energy density between plates than outside of them. It's only "negative" if you fix zero point energy level to vacuum; this may not be the case. Even though the recent reduction in estimated energy requirement made it slightly more feasible, there are still several hurdles of "we have no idea if this is possible, much less how to actually do it" left.
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But, for practical purposes, if Alcubierre drive allows traveling from A to B faster than distance between A to B seems to be I would call it FTL travel and be done with it.
You didn't understand the criticism against the AD.
You can well create (theoretically) a drive that shortens the distance between A and B. What you (and many others!) are missing is that the process of "shortening up" the distance between A and B is through gravitational waves... which travel at light speed! See the problem? You can't get around this.
Perhaps something like creating "lanes" would eventually be possible. Really far fetched and not at all what is being discussed when speaking about ADs, since they depend on the idea of not only shortening AB but also lengthening AB in the "back" of the drive. Since this process cannot happen faster than the waves making the lane, you are still travelling slower than light.
Yeah, well, the problem with uncharted territory is you don't know what's behind the next hill until you get an overhead satellite pass to give you a picture.
But we do have a lot of pictures. They are all quite pessimistic in this notion. You are of course free to dream, but never should be under the illusion that current physics are giving you hints for your optimisms, for they are clearly not.
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With the quantum entangled particles, why not just have one pair dedicated to communications from A to B, and another pair for B to A? Then have them constantly transmitting on a frequency, and being measured at the other end at the same frequency. Obviously, measuring changes the value, but you know that and this simply invert the values read. The only problem would be if the transmitting and measuring processes got out of sync, but then you could just try flipping all the values read to their inverse past the point where the data became unreadable, and keep it inverted until the next out of sync. Obviously you'd want parity checks, yes? So you would know if the data stream became unsyncronized.
Now, what am I missing? I'm sure that can't be the answer, someone would have tried it already.
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Well, when you eventually cancel all the fuzzinesses and ambiguities you are left where you began: with an unuseful device for FTL comms. The maths become hard really fast and I'm no expert on this at all, so I refer to Lubos Motl in the Physics Stack Exchange fora:
There is no experiment in which genuine information could be sent faster than light and there is no contradiction between this fact and quantum mechanics – as built by the Copenhagen school. Quite on the contrary, the proper, Copenhagen-like interpretation of quantum mechanics is needed for a description of known experiments that is compatible with special relativity and its most general consequences, locality and causality.
You would have to describe your experiment in detail if you wanted the interference and its disappearance to be discussed seriously.
However, quite generally, if there are entangled pairs produced, a single particle from this pair won't contribute to an interference pattern by itself. (A typical example is an entangled electron-photon pair where the electron participates in a double-slit experiment and the photon is used to "look" at the electron. The photon gets entangled with the electron but the electron's own interference pattern disappears.) The interference pattern may only be glimpsed if one compares some appropriate measured properties of both particles in the entangled pair. But that's only possible much later, when these results of measurements are communicated to a single place, and because the comparison occurs much later, it can't be used to transmit any information faster than light.
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I thought this thread was about lightsabers. Boy was I wrong! It's about FTL travel!
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With the quantum entangled particles, why not just have one pair dedicated to communications from A to B, and another pair for B to A? Then have them constantly transmitting on a frequency, and being measured at the other end at the same frequency. Obviously, measuring changes the value, but you know that and this simply invert the values read. The only problem would be if the transmitting and measuring processes got out of sync, but then you could just try flipping all the values read to their inverse past the point where the data became unreadable, and keep it inverted until the next out of sync. Obviously you'd want parity checks, yes? So you would know if the data stream became unsyncronized.
Now, what am I missing? I'm sure that can't be the answer, someone would have tried it already.
This would rely on absolutely precise synchronization between the two readers, which is pretty much impossible to guarantee (especially if one or both of them are in motion). Also, your parity checking would need to be done via normal, known secure methods, thus invalidating any supposed speed advantage.
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That precise sync is also inherently impossible due to the uncertainty principle. QED.
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Here's my attempt at explaining why it doesn't work:
1. You cannot measure the state of an entangled particle without altering said state.
2. When you measure the particle, there is no way for you to tell whether or not it has been altered by a measurement the other person took, or whether it's due to some other interaction.
3. As such, you would need confirmation that an alteration has happened (and what exactly that alteration was!) delivered through traditional means, which are of course not FTL.
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I think that's not exactly it, I've seen the actual physics explanation some time ago and it did hurt my brain a little. The reason I say it's probably not that is because that seems easily solvable. If you have for instance 10 or 20 pairs of entangled electrons or wtv you can have your confirmation through sheer numbers / statistics by correlation. Error prone, but still possible (I think!).
Thing is, the data is inherently incomplete until you get the other piece of the measurement. Which seems weird and counter-intuitive, for it hints that a transmission of some kind happened, but not at all at the same time. That a piece of information was sent but not exactly at the same time. And that's exactly it, that's Quantum Mechanics for ya!
It all seems to behave weirdly and violating GR everywhere, but when you actually do the maths and try to account for everything, we see that it does not in fact, that the "information" sent FTL was not sufficient to even be labeled as "information".
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It's easy to directly convert matter to energy; campfires.
Noooooo. A campfire does NOT transfer any matter directly to energy. The light and heat produced by a fire are a result of energy transferring forms; a fire is an exothermic reaction in which the potential energy in the chemical bonds of the fuel source (like wood, for instance) is converted into infrared and visible light. If you set up a controlled closed environment in which to burn something, which several notable chemists did starting in the 1700s, you'd find that the total mass of the reactants was equal to that of the products; it turns out that conservation of mass is kind of a big deal. Technically you'd see a veeeeery small reduction in mass due to the release of electromagnetic energy, but it's miniscule enough that you'd need very precise instruments to observe it. You'd need to look at nuclear reactions to see the conversion of matter to energy in a truly-noticeable sense in relation to the reactant masses involved. It's not really "easy" in the sense that you can do it with stuff you find around your house, though it is something that humanity as a whole does routinely every day.
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You can well create (theoretically) a drive that shortens the distance between A and B. What you (and many others!) are missing is that the process of "shortening up" the distance between A and B is through gravitational waves... which travel at light speed! See the problem? You can't get around this.
I can't find any reference to gravitational waves on the Wikipedia article for the Alcubierre Drive (http://en.wikipedia.org/wiki/Alcubierre_drive)...
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Noooooo. A campfire does NOT transfer any matter directly to energy. The light and heat produced by a fire are a result of energy transferring forms; a fire is an exothermic reaction in which the potential energy in the chemical bonds of the fuel source (like wood, for instance) is converted into infrared and visible light. If you set up a controlled closed environment in which to burn something, which several notable chemists did starting in the 1700s, you'd find that the total mass of the reactants was equal to that of the products; it turns out that conservation of mass is kind of a big deal. Technically you'd see a veeeeery small reduction in mass due to the release of electromagnetic energy, but it's miniscule enough that you'd need very precise instruments to observe it. You'd need to look at nuclear reactions to see the conversion of matter to energy in a truly-noticeable sense in relation to the reactant masses involved. It's not really "easy" in the sense that you can do it with stuff you find around your house, though it is something that humanity as a whole does routinely every day.
Conservation of mass is a big thing indeed. Most of the output from a camp fire is smoke, other gasses, carbon.. It might a crude form of converting matter to energy. However, you're still at least getting infrared and visible light output from wood. I know what you mean though. That lighting a fire starts a tiny process of matter to energy conversion but that that what is happening in the least since most of the output from a fire is matter; that a fire is mostly conversion of matter to other forms of matter.
Nukes would be a better example?
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Noooooo. A campfire does NOT transfer any matter directly to energy. The light and heat produced by a fire are a result of energy transferring forms; a fire is an exothermic reaction in which the potential energy in the chemical bonds of the fuel source (like wood, for instance) is converted into infrared and visible light. If you set up a controlled closed environment in which to burn something, which several notable chemists did starting in the 1700s, you'd find that the total mass of the reactants was equal to that of the products; it turns out that conservation of mass is kind of a big deal. Technically you'd see a veeeeery small reduction in mass due to the release of electromagnetic energy, but it's miniscule enough that you'd need very precise instruments to observe it. You'd need to look at nuclear reactions to see the conversion of matter to energy in a truly-noticeable sense in relation to the reactant masses involved. It's not really "easy" in the sense that you can do it with stuff you find around your house, though it is something that humanity as a whole does routinely every day.
Conservation of mass is a big thing indeed. Most of the output from a camp fire is smoke, other gasses, carbon.. It might a crude form of converting matter to energy. However, you're still at least getting infrared and visible light output from wood. I know what you mean though. That lighting a fire starts a tiny process of matter to energy conversion but that that what is happening in the least since most of the output from a fire is matter; that a fire is mostly conversion of matter to other forms of matter.
Nukes would be a better example?
Aaaaaaack nooooooo. A fire is not mass->energy conversion. Period. You're taking a material at a stable high-energy state, and performing a chemical reaction to result in low-energy but high-entropy byproducts. Conservation of mass isn't just a "big thing", it's the ONLY thing.
Nuclear reactions, and practically speaking nuclear reactions ONLY, involve mass->energy conversion.
(Ok, fine, obnoxious pendant corner: photons do have mass, so any EM energy emitted by a burning campfire would "carry away" an amount of mass commensurate with the energy radiated. However, this amount of energy is unspeakably miniscule compared to the total binding energy of a campfire's fuel, so for any real-world purpose is utterly negligible. To put into perspective just how much energy is tied up in the very being of matter, complete conversion of a single gram of matter to energy would release about as much energy as a super-high-yield thermonuclear weapon. (http://en.wikipedia.org/wiki/Tsar_Bomba) Now compare that against a couple kilos of firewood. Yeah, there's a reason nobody counts mass loss from combustive EM emissions.)
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You can actually precisely calculate the mass -> energy transformation in a chemical reaction such as combustion.
If you have a molecule such as C2H5OH, and a stoichiometric amount of O2 (I'm too lazy to actually calculate the ideal ratio), turns out these molecules are slightly more massive than the chemicals resulting from them reacting - CO2 and H2O.
The energy of the chemical bonds counts as mass. Ethyl alcohol and oxygen molecule are in a higher energy state than the reaction results (carbon dioxide and water). So when you introduce enough energy into a system of ethanol and oxygen to go over the disassociation energy barrier, to split these molecules into individual atoms, the soup of atoms ends up reconfiguring it at the "easiest", aka. lowest energy configuration. The energy difference (or enthalpy) is typically transitioned to relative energy forms - kinetic energy, rotational energy, and electromagnetic radiation.
The chemical energy in the bonds does have an effect on a molecule's mass. However, you are right in that the mass difference in chemical reactions is so insignificantly small that generally it can be said that conservation of mass applies in chemical reactions. That is because the ratio between energy and mass is c2, which is a large number, and chemical reactions typically don't produce very much energy - you need quite a lot of reactants to produce meaningful amount of energy.
In nuclear reactions the mass difference is actually measurable and that's why nuclear reactions produce so much energy from seemingly small amount of reactants.
In short: Chemical energy is differences in energy configurations of electrons. Nuclear energy is differences in energy configurations of protons and neutrons.
Since electron configurations are purely a result of electromagnetic interactions (in the quantum mechanical sense) and nuclear configurations are a result of mostly strong nuclear interaction*, it makes perfect sense that there is a lot more energy involved in nuclear configurations, compared to electron configurations. Strong nuclear interaction is just so much stronger than electromagnetic interaction.
*Nuclear configurations can also be affected by weak nuclear interaction, which is responsible for such things as electron capture where proton and electron interact and the proton changes into a neutron, and if I recall right the reaction also produces an electron neutrino. But in nuclear scale, the strong nuclear force vastly overpowers electromagnetic force which is, happily, the reason why matter stays intact. It's also the main reason why physically very large nuclei form instabilities in heavy elements, and become radioactive - the nuclear binding energy is reducing as radius of nucleus increases, while the electromagnetic repulsive energy increases as the amount of positive charges increases...
But, for practical purposes, if Alcubierre drive allows traveling from A to B faster than distance between A to B seems to be I would call it FTL travel and be done with it.
You didn't understand the criticism against the AD.
I did, you just didn't understand why your critique was invalid.
You can well create (theoretically) a drive that shortens the distance between A and B. What you (and many others!) are missing is that the process of "shortening up" the distance between A and B is through gravitational waves... which travel at light speed! See the problem? You can't get around this.
Your critique would be right if Alcubierre Drive were a "wave rider" of sorts.
Instead, it is based on creating new space behind the ship while reducing the amount of space ahead of it. Expansion and contraction of space are not in any way limited by the speed of light.
In short, Alcubierre drive would actually create an event horizon behind it since space there would be expanding faster than light can travel through it. On the front end, though, there's an opposite problem since the drive would essentially contract the space ahead - with all the photons included in that space that happen to be in it, and that would cause insane photon density.
A more valid critique would be to ask how the space-time expansion is contained so that it only translates to ship apparently moving and not, say, the universe suddenly splitting in half.
Perhaps something like creating "lanes" would eventually be possible. Really far fetched and not at all what is being discussed when speaking about ADs, since they depend on the idea of not only shortening AB but also lengthening AB in the "back" of the drive. Since this process cannot happen faster than the waves making the lane, you are still travelling slower than light.
This is basically the "stargate" method - creating a wormhole between two devices, then moving one device somewhere else while keeping the wormhole connected. Rate of creating these traveling methods would indeed be limited by how fast the other end can be transported, but once the wormhole is established, traveling through it does offer a true "bypass lane" over the limitations of space-time continuum - in effect, it creates a space-time connection between two positions that is separate from the traveling distance. This is completely free of any paradoxes, too.
Yeah, well, the problem with uncharted territory is you don't know what's behind the next hill until you get an overhead satellite pass to give you a picture.
But we do have a lot of pictures. They are all quite pessimistic in this notion. You are of course free to dream, but never should be under the illusion that current physics are giving you hints for your optimisms, for they are clearly not.
We don't have pictures, we have "artist's impressions", which is a fancy way of saying we have theories and visualizations based on those theories. These should be kept separate from actual empirical data.
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But, for practical purposes, if Alcubierre drive allows traveling from A to B faster than distance between A to B seems to be I would call it FTL travel and be done with it.
Distance between A and B: Looks about 100 ly away. If I go at 0.9c it'll take about 111 years.
Accelerate to 0.9c: Oh, it only looks 44 ly now, it should only take 48 years.
Yay, I went 100 ly in 48 years, I FTL
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But, for practical purposes, if Alcubierre drive allows traveling from A to B faster than distance between A to B seems to be I would call it FTL travel and be done with it.
Distance between A and B: Looks about 100 ly away. If I go at 0.9c it'll take about 111 years.
Accelerate to 0.9c: Oh, it only looks 44 ly now, it should only take 48 years.
Yay, I went 100 ly in 48 years, I FTL
It needs to apply in the original reference frame, though.
I am fully aware that time dilation will make the travel time shorter the closer you get to light speed (or, alternative explanation - the travel distance experiences Lorentz contraction and becomes shorter) but it will still take too much time to really explore the galaxy and every long distance travel will be strictly one-way - which is no way for scientific exploration to operate. It would work for colonization missions, but even if you push the speed closer to c and thus reduce travel time for the ship itself - you encounter situations where thousands of years will progress on Earth with months or years for the ships occupants.
And it's even worse if you don't send people, because then the only advantage is that your unmanned research probe won't age, but it will still take hundreds or thousands of years until it actually seems to get to its destination... and in fact it'll look like twice that time because the further it gets, the longer it takes for signals to get to Earth. We'll be able to track its progress in "real-time" but there will be an ever-increasing delay between the time when the probe does something and the time we receive the image it took or whatever. And it would of course need to be autonomous because trying to control robots on MARS is a pain in the neck, never mind several years of control delays.
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So I just found out I never replied to this and so here I am :D.
But, for practical purposes, if Alcubierre drive allows traveling from A to B faster than distance between A to B seems to be I would call it FTL travel and be done with it.
You didn't understand the criticism against the AD.
I did, you just didn't understand why your critique was invalid.
You can well create (theoretically) a drive that shortens the distance between A and B. What you (and many others!) are missing is that the process of "shortening up" the distance between A and B is through gravitational waves... which travel at light speed! See the problem? You can't get around this.
Your critique would be right if Alcubierre Drive were a "wave rider" of sorts.
Instead, it is based on creating new space behind the ship while reducing the amount of space ahead of it. Expansion and contraction of space are not in any way limited by the speed of light.
In short, Alcubierre drive would actually create an event horizon behind it since space there would be expanding faster than light can travel through it. On the front end, though, there's an opposite problem since the drive would essentially contract the space ahead - with all the photons included in that space that happen to be in it, and that would cause insane photon density.
A more valid critique would be to ask how the space-time expansion is contained so that it only translates to ship apparently moving and not, say, the universe suddenly splitting in half.
You see, you say you understood the critique and then bluster right through it. Let's try this again, I *get* the mechanism. I get the "expansion or contraction" of space thing. What you are missing is that the space itself has to acquire the information that is being compacted. The only known mechanism in physics on how this happens is through gravitational waves. You have to communicate to space itself that you want it to contract itself and in what manner. This is what you cannot communicate FTL.
And, anyway, the AD is really simple to defuse as a theoretical concept by fiat. If you picture a "surrounding sphere" of a million kms that encompasses the ship, the drive, the space being contracted, etc., you can judge it theoretically as a kind of a particle in the universe and analyse it accordingly. This "particle" cannot travel faster than light, period.
I have watched silly talks about the AD, supposedly by smart people, trying to get around the time travel paradoxes that it would imply, and their solution was something of the sort of a traffic legalization, forbidding certain closed paths and so on. It's remarkably silly, as if they were trying to prevent the universe from figuring out that they were cheating its laws.
This is basically the "stargate" method - creating a wormhole between two devices, then moving one device somewhere else while keeping the wormhole connected. Rate of creating these traveling methods would indeed be limited by how fast the other end can be transported, but once the wormhole is established, traveling through it does offer a true "bypass lane" over the limitations of space-time continuum - in effect, it creates a space-time connection between two positions that is separate from the traveling distance. This is completely free of any paradoxes, too.
Yes, this would be apparently free of paradoxes, although the fact that one mouth of the wormhole is accelerated will bring about severe problems and bring back the time paradox issues to light. Some literature exists over this, and it seems to point out that differently accelerated mouths will obviously create different time relations, but because this is incompatible with the requirement that both mouths must be perfectly synchronized, the hole just collapses.
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Aaaaaaack nooooooo. A fire is not mass->energy conversion. Period. You're taking a material at a stable high-energy state, and performing a chemical reaction to result in low-energy but high-entropy byproducts. Conservation of mass isn't just a "big thing", it's the ONLY thing.
Nuclear reactions, and practically speaking nuclear reactions ONLY, involve mass->energy conversion.
(Ok, fine, obnoxious pendant corner: photons do have mass, so any EM energy emitted by a burning campfire would "carry away" an amount of mass commensurate with the energy radiated. However, this amount of energy is unspeakably miniscule compared to the total binding energy of a campfire's fuel, so for any real-world purpose is utterly negligible. To put into perspective just how much energy is tied up in the very being of matter, complete conversion of a single gram of matter to energy would release about as much energy as a super-high-yield thermonuclear weapon. (http://en.wikipedia.org/wiki/Tsar_Bomba) Now compare that against a couple kilos of firewood. Yeah, there's a reason nobody counts mass loss from combustive EM emissions.)
It's such a horrible example i see why it's not counted as a conversion now. Just because of it's extreme minisculity. And candidates for real considerration are few.
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You see, you say you understood the critique and then bluster right through it. Let's try this again, I *get* the mechanism. I get the "expansion or contraction" of space thing. What you are missing is that the space itself has to acquire the information that is being compacted. The only known mechanism in physics on how this happens is through gravitational waves. You have to communicate to space itself that you want it to contract itself and in what manner. This is what you cannot communicate FTL.
You only need to expand or contract the space that is right next to the ship. There's no need to affect anything faster than light.
Besides, I wouldn't go so far as to say that gravitational waves are the only way to change the space-time curvature. That's a fallacy because gravitational waves are propagating variations of space-time curvature - they don't explain what makes the space curved. There is a thing we only have a name for that apparently has the effect of negative pressure (or anti-gravity) on the entire universe. We don't understand why the universe expanded so rapidly during the inflation phase of the big bang. We don't even understand why mass curves space-time - we just have witnessed that it does, and we have a pretty good theoretical model to analyze mass-space-time interactions - it's called General Relativity.
And, anyway, the AD is really simple to defuse as a theoretical concept by fiat. If you picture a "surrounding sphere" of a million kms that encompasses the ship, the drive, the space being contracted, etc., you can judge it theoretically as a kind of a particle in the universe and analyse it accordingly. This "particle" cannot travel faster than light, period.
Your argument is simple to defuse by empirical observation that there are a hell of a lot of particles in the universe that are moving away from us faster than light. You only need to look deep enough, and you see an event horizon which hides the rest of the universe racing away from us.
And, like I just said, that expansion is acceleration due to... something that we just have a name for, and some sort of rudimentary observational formula for how it accelerates the expansion of our universe.
I have watched silly talks about the AD, supposedly by smart people, trying to get around the time travel paradoxes that it would imply, and their solution was something of the sort of a traffic legalization, forbidding certain closed paths and so on. It's remarkably silly, as if they were trying to prevent the universe from figuring out that they were cheating its laws.
They probably seem silly to you because you lack the theoretical understanding to comprehend what they're talking about. I have seem the same thing with people who are opposed to evolution, natural selection, WTC collapse without being "inside job", or indeed the Big Bang itself. These people all had the common denominator of criticizing things they didn't really understand.
And I'll openly admit that I don't have the understanding to critique something like Miguel Alcubierre's (speculative) solution to Einstein's field equations from the general relativity.
However, the people who come up with this stuff have made it their life's work to do it and experiment with it and figure out what's possible and what's currently not. As far as I understand, no one has proven Alcubierre's solution mathematically incorrect; having been published in a peer-reviewed magazine and survived for several years, someone probably would have caught a mathematical error by now.
So it appears to remain a viable solution that is compatible with general relativity - which is the aforementioned model that is currently the best available for predicting mass-spacetime interactions.
Whether or not it is actually possible, or if general relativity itself is wrong in this regard - that remains to be seen, but it needs to be tested because not even all the king's men together with all the king's horses and a court magician with best armchair physics in the kingdom can't prove OR disprove it.
They need to either have someone come up with a "look, you put a + here instead of -" or to figure out an experiment that can conclusively disprove the Alcubierre solution.
This is basically the "stargate" method - creating a wormhole between two devices, then moving one device somewhere else while keeping the wormhole connected. Rate of creating these traveling methods would indeed be limited by how fast the other end can be transported, but once the wormhole is established, traveling through it does offer a true "bypass lane" over the limitations of space-time continuum - in effect, it creates a space-time connection between two positions that is separate from the traveling distance. This is completely free of any paradoxes, too.
Yes, this would be apparently free of paradoxes, although the fact that one mouth of the wormhole is accelerated will bring about severe problems and bring back the time paradox issues to light. Some literature exists over this, and it seems to point out that differently accelerated mouths will obviously create different time relations, but because this is incompatible with the requirement that both mouths must be perfectly synchronized, the hole just collapses.
Why would the hole just collapse? There's no requirements that I know of that require two points in space-time to be synchronized to each other (in fact, two points in space-time rarely are synchronized in any way anyway).
Wormholes have other issues that would be much more pressing, like the fact that you just made a black hole appear right in your vicinity and you have to deal with the insane tidal forces and make the wormhole itself stable (which, by the way, requires the same exotic matter that is supposedly required to make Alcubierre Drive work!) and possible to go through without becoming tissue spaghetti heated to luminous plasma on the way.
Do feel free to come up with more ideas to disprove the impossibility of this or that scientific hypothesis, but please keep in mind that Alcubierre drive is a theoretically valid solution derived from General Relativity, and you're basically trying to disprove it by basic arguments from General Relativity.
I can't help but think that these clever people would've noticed this by themselves if it really were as simple to disprove as what you're suggesting.