263 réponses à ce sujet

[JKoopman]

jamesp81 wrote...

JKoopman wrote...

Technically speaking, the mass effect would account for a spacecraft being capable of traveling AT the speed of light. But reducing a ship's mass--even to zero--wouldn't allow it to travel FASTER than light. You'd need some kind of wormhole for that to occur, and that's not really FTL so much as it is teleportation.

I wonder if eezo can make your mass negative.....this might allow FTL.

I'm not sure if negative mass is even a valid concept. I mean, mass is basically the density of matter in an object. You can reduce it to the point where that density is effectively zero, but beyond that? It's kind of like saying "negative vacuum". What even is that? Would negative mass actually be mass in and of itself? Or would it be some other form of mass, like dark energy or antimatter?

Modifié par JKoopman, 01 avril 2011 - 07:35 .

[Phaedon]

Hawking says it is, if I remember correctly. Imagine spacetime as a sheet, and negative mass being able to turn it around. And I think that Casimir Effect has something to do with this...

[JKoopman]

Phaedon wrote...

Hawking says it is, if I remember correctly. Imagine spacetime as a sheet, and negative mass being able to turn it around. And I think that Casimir Effect has something to do with this...

So it might be something like an alternate/reverse dimension?

The only assumption I can make about negative mass would be that it would likely repell objects with mass from it rather than attracting them as an object with mass would. It's kind of an odd subject.

[abstractwhiz]

You're thinking of mass in terms of something physical. Think of it as a variable in an equation instead. If the mathematics of your theory doesn't prohibit that variable from being negative, and its predictions match experiment outcomes, then mass can be negative. At that point, you need to go make up a new mental analogy to make the cognitive dissonance go away. Relying on human intuitions is an epic fail - the universe does not work that way. Our minds are freakish and weird, if we don't follow the mathematics, we risk a misperception of reality by trying to force it into patterns we find comfortable and understandable. But it has no obligation to be that way. As the physicists would say, "Shut up and calculate!"

[Fiery Phoenix]

Negative mass isn't just a crazy and baseless idea, JK. There is some basis to it; it's simply unlike anything we can imagine. Look it up. Very fascinating stuff, although purely theoretical at this point.

[Praetor Knight]

I wonder what this dude could add,

[Fiery Phoenix]

I wish he was still alive.

[Whatever42]

Well, according to the physists, there there is nothing in the math that mandates that time only travel in one direction but clearly there is an "arrow of time". Physists are even tring to determine why time only goes in one direction even though the math says its fine.

[JKoopman]

SomeKindaEnigma wrote...

Again, the problem with quantum entanglement as possibly being used as communication devices is that no information can travel faster than the speed of light. Relatively speaking, it would actually be useful on Earth considering the diameter of the Earth < distance traveled by light in one second, so communications that way can be done in less than a second. If you try to set up communications through entanglement between, for example, the earth and a spacecraft a considerable distance away, obviously you still have to account for a time delay to receive the information from the partner particle.

I thought that was the point; that the whole idea behind quantum entagled particles was that they defied the relativistic speed limit of light? That no matter where in the universe those particles were and no matter how far apart, one particle would always be the exact opposite of it's sister particle and any change in the state of one particle would be instantly reflected in the other.

That would seem to make the instantaneous transmission of information via binary code at least theoretically possible, would it not? Although, granted, I'm no particle physicist.

[abstractwhiz]

He never liked entanglement anyway.  He actually (along with Podolsky and Rosen) came up with a thought experiment to demonstrate why it couldn't be true - the so-called EPR paradox.

Unfortunately, they never imagined that someone would actually do the bloody experiment, and it didn't turn out in their favor.

QM is somewhat ugly (mathematically) compared to the beautiful simplicity of relativity. Einstein wasn't the only one who disliked it. If it hadn't been so spectacularly successful, physicists would have thrown it out decades ago.

[squidney2k1]

Faster Than Light SPEED is not possible.

However, Faster Than Light TRAVEL is.

The theories speculate that it's possible to fold space (and therefore time, itself), shortening the distances between two points in 3D space. It's suggested that this could be achieved via a wormhole, black hole/singularity, or the fictional "warp" or gravetron drive. The main reason why this is accepted as possible is that gravity itself is the result of space warping and folding back upon itself, and this occurs at every point in the universe, from the massive scale (black hole), right down to the miniscule (quantum physics and particle theory). Because Gravity is a weak force in the universe, it's also the most easily manipulated...we just haven't figured out how to do so.


You can't get to from A to B by moving faster than the speed of light...but you can get from A to B faster, if you shorten the distance between them.

[abstractwhiz]

JKoopman wrote...

SomeKindaEnigma wrote...

Again, the problem with quantum entanglement as possibly being used as communication devices is that no information can travel faster than the speed of light. Relatively speaking, it would actually be useful on Earth considering the diameter of the Earth < distance traveled by light in one second, so communications that way can be done in less than a second. If you try to set up communications through entanglement between, for example, the earth and a spacecraft a considerable distance away, obviously you still have to account for a time delay to receive the information from the partner particle.

I thought that was the point; that the whole idea behind quantum entagled particles was that they defied the relativistic speed limit of light? That no matter where in the universe those particles were and no matter how far apart, one particle would always be the exact opposite of it's sister particle and any change in the state of one particle would be instantly reflected in the other.

That would seem to make the instantaneous transmission of information via binary code at least theoretically possible, would it not? Although, granted, I'm no particle physicist.

The particles themselves are still subject to the speed of light constraint. If you want to communicate with something a light-year away, you'd have to move one of the particles there, which will take a year at minimum. Then you can communicate instantaneously - one single bit of information. Seems like a lot of trouble to go to for a Yes or No answer.

[Praetor Knight]

abstractwhiz wrote...

He never liked entanglement anyway.  He actually (along with Podolsky and Rosen) came up with a thought experiment to demonstrate why it couldn't be true - the so-called EPR paradox.

Unfortunately, they never imagined that someone would actually do the bloody experiment, and it didn't turn out in their favor.

QM is somewhat ugly (mathematically) compared to the beautiful simplicity of relativity. Einstein wasn't the only one who disliked it. If it hadn't been so spectacularly successful, physicists would have thrown it out decades ago.

True, the framework I was considering is that his work allowed us to get to our current understanding, and if he knew then what we know now, I figure that he might have been able to provide more interesting insights.

[JKoopman]

abstractwhiz wrote...

JKoopman wrote...

SomeKindaEnigma wrote...

Again, the problem with quantum entanglement as possibly being used as communication devices is that no information can travel faster than the speed of light. Relatively speaking, it would actually be useful on Earth considering the diameter of the Earth < distance traveled by light in one second, so communications that way can be done in less than a second. If you try to set up communications through entanglement between, for example, the earth and a spacecraft a considerable distance away, obviously you still have to account for a time delay to receive the information from the partner particle.

I thought that was the point; that the whole idea behind quantum entagled particles was that they defied the relativistic speed limit of light? That no matter where in the universe those particles were and no matter how far apart, one particle would always be the exact opposite of it's sister particle and any change in the state of one particle would be instantly reflected in the other.

That would seem to make the instantaneous transmission of information via binary code at least theoretically possible, would it not? Although, granted, I'm no particle physicist.

The particles themselves are still subject to the speed of light constraint. If you want to communicate with something a light-year away, you'd have to move one of the particles there, which will take a year at minimum. Then you can communicate instantaneously - one single bit of information. Seems like a lot of trouble to go to for a Yes or No answer.

True. But that's like saying that calling your neighbor on the phone would take just as long as walking to their house, because they have to go out and buy a phone first. Once that particle was in place, you would effectively have a reusable faster-than-light method of communication across a vast distance.

Modifié par JKoopman, 01 avril 2011 - 08:00 .

[abstractwhiz]

It's not reusable. The entanglement is broken once you observe the particle. If you want to send one more bit of information, you need to send another particle.

In Charles Stross's Eschaton novels, this is how FTL communication is done. People on one end create a ton of entangled pairs, and fly them to a distant colony on normal subliminal ships. After a while, they run out, so another ship comes by.

[Whatever42]

abstractwhiz wrote...
The particles themselves are still subject to the speed of light constraint. If you want to communicate with something a light-year away, you'd have to move one of the particles there, which will take a year at minimum. Then you can communicate instantaneously - one single bit of information. Seems like a lot of trouble to go to for a Yes or No answer.

Except as I understand it, that still wouldn't work because you would have to send a message telling the holder of that particle that you sent a message.

[jamesp81]

Raith Mano wrote...

jamesp81 wrote...

AlanC9 wrote...

jamesp81 wrote...
The reason space exploration has been shelved is because of lack of vision.

The modern scientific establishment guys will stand on a podium and preach a sermon to you about what you can't do and what is impossible.

It will require a visionary to discover what IS possible.  Someone with scientific training but without the establishment mindset.  Visionaries are derided and scorned as fools, so you don't see many of them.

The problem with this logic is that a lot of visionaries are fools.

So?

I can guarantee you the science establishment is never going to undertake the task of trying to discover the secret of FTL travel or any other large, ambitious project.  It's not in their mindset.

Without visonaries we wouldn't have a lot of the amazing tech we have today.  If someone 40 years ago said that it was possible to have a phone so small it could fit in your pocket and have more computing power than all the Appolo rockets combined they would have told you that you were high off your a**.  Visonaries are what keeps the world moving. 

The problem with current federally funded research projects is that they want results they can make money off of, so they're afraid to venture into the unknown.  If you gave a company all the money they could use for the next 15-20 years, we'd be on Mars by 2025 with a large human presence.

Science is only stunted by funding and how much can be made, not imagination and visionaries.

The government does federally fund some wild projects through DARPA, but that's all defense related.  And while some of those projects end up having huge private sector ramifications (the internet, for example, was not invented by Al Gore but was funded by DARPA) I don't see FTL travel being something they'd care about.

[abstractwhiz]

Whatever666343431431654324 wrote...

abstractwhiz wrote...
The particles themselves are still subject to the speed of light constraint. If you want to communicate with something a light-year away, you'd have to move one of the particles there, which will take a year at minimum. Then you can communicate instantaneously - one single bit of information. Seems like a lot of trouble to go to for a Yes or No answer.

Except as I understand it, that still wouldn't work because you would have to send a message telling the holder of that particle that you sent a message.

Right. I just thought about it, and based on my limited knowledge (not a physicist - computer science grad student who took a graduate level quantum computing class), it's probably even worse. When the sender observes his particle, it'll fall into one of its two binary states, with some probability for each (say 50-50). The receiver's particle will then always be observed in the corresponding state with 100% probability. (Corresponding = same state or opposite state - that depends on how the system is entangled. You could have them mimic each other, or be opposite.)

Now, if you wanted to send a 0, and that's what you observed, you're fine. But if you wanted to send a 1, now you have to let the receiver know to flip that bit, so he gets the right message. But how are you going to tell the receiver that? Oh right, slower than light ommunication. So... <_<

[abstractwhiz]

Bah - double post. <_<

Modifié par abstractwhiz, 01 avril 2011 - 08:59 .

[vimpel]

STFU AND PLAY!

[jamesp81]

Whatever666343431431654324 wrote...

jamesp81 wrote...

The problem with that is plants gain most of their actual energy from nutrients in the soil.  The soil itself is insufficient as an energy source.


Solar won't work well for the obvious reasons unless you put the solar collectors in a high polar orbit where they always face the sun, and send the collected energy down to receiving station.

Right now, the only practical solution is nuclear power for large scale, base-load generation (with better flood walls).  For vehicle fuels, some kind of just-in-time on the spot hydrogen production is probably the most practical thing.  Nuclear will be the only real, long term option until someone figures out a way to control a fusion reaction without blowing themselves to hell and gone.

Well, I'll disagree with you. There is more than enough solar energy to provide any possible energy needs we have. The problem is to simply make it economical.  Nuclear is an awful solution, its almost an uneconomic as solar and its dangerous.

As for where most plants get their energy from, yes, that's why people are trying to bioengineer better plants. And algae doesn't get most of its energy from the soil, obviously.

Solar energy is problematic to trap.  Also, the Earth's atmosphere filters out almost all energy put out by the sun (this is, of course, a good thing since that radiation is largely deadly).  Solar cannot be made economical by restricting oneself to planet side collectors.  You either do it with orbital collectors or you don't do it at all.

Contrary to your belief on the matter, nuclear is extremely cost effective.  The start up costs are relatively high, the cost per kilowatt hour of electricity produced with nuclear is much less than other forms of base-load generation.  As for the danger, the obvious solution there is to do the same with nuclear plants that are done with coal plants: don't build the damned things in populated areas.  As an industry, coal power generation is directly responsible for more industrial accidents and deaths than the nuclear power industry, BY FAR.  I live in coal mining country, I've got some perspective on this.  Coal mining is dangerous as hell and it always will be.

[jamesp81]

JKoopman wrote...

jamesp81 wrote...

JKoopman wrote...

Technically speaking, the mass effect would account for a spacecraft being capable of traveling AT the speed of light. But reducing a ship's mass--even to zero--wouldn't allow it to travel FASTER than light. You'd need some kind of wormhole for that to occur, and that's not really FTL so much as it is teleportation.

I wonder if eezo can make your mass negative.....this might allow FTL.

I'm not sure if negative mass is even a valid concept. I mean, mass is basically the density of matter in an object. You can reduce it to the point where that density is effectively zero, but beyond that? It's kind of like saying "negative vacuum". What even is that? Would negative mass actually be mass in and of itself? Or would it be some other form of mass, like dark energy or antimatter?

I think it would be, although I'm inferring.  I know that the concept of negative energy has been around for a while, and mass and energy are inextricably related and bound to one another.

[termokanden]

Raith Mano wrote...

jamesp81 wrote...

AlanC9 wrote...

jamesp81 wrote...
The reason space exploration has been shelved is because of lack of vision.

The modern scientific establishment guys will stand on a podium and preach a sermon to you about what you can't do and what is impossible.

It will require a visionary to discover what IS possible.  Someone with scientific training but without the establishment mindset.  Visionaries are derided and scorned as fools, so you don't see many of them.

The problem with this logic is that a lot of visionaries are fools.

So?

I can guarantee you the science establishment is never going to undertake the task of trying to discover the secret of FTL travel or any other large, ambitious project.  It's not in their mindset.

Without visonaries we wouldn't have a lot of the amazing tech we have today.  If someone 40 years ago said that it was possible to have a phone so small it could fit in your pocket and have more computing power than all the Appolo rockets combined they would have told you that you were high off your a**.  Visonaries are what keeps the world moving. 

The problem with current federally funded research projects is that they want results they can make money off of, so they're afraid to venture into the unknown.  If you gave a company all the money they could use for the next 15-20 years, we'd be on Mars by 2025 with a large human presence.

Science is only stunted by funding and how much can be made, not imagination and visionaries.

Well there's a lot to comment on here. I could talk about why science is not always moving in the right direction, but I always get carried away.

The scientific community isn't against visionaries or breakthroughs. There is just so much garbage science out there that you have to be extremely careful. Particularly because it is not obvious to non-scientists whether something is a brilliant vision, the ramblings of a madman, or just random nonsense.

[Raanz]

...for now.

[Tamcia]

The current scientific perception might say it is impossible. How many times has that changed during human history? Its just theorycrafting. With new levels of understanding, you can push the bar of what is possible.