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Near Light Speed Travel Possible After All?
DrStrabismus writes "PhysOrg has a story about research that may indicate that close to light speed travel is possible. From the article: 'New antigravity solution will enable space travel near speed of light by the end of this century, he predicts. On Tuesday, Feb. 14, noted physicist Dr. Franklin Felber will present his new exact solution of Einstein's 90-year-old gravitational field equation to the Space Technology and Applications International Forum (STAIF) in Albuquerque. The solution is the first that accounts for masses moving near the speed of light.'"
Theres no point in travelling at close to light speed if your have no way of stopping.
Mind that planet!
What planet?
SPLAT
liqbase
Can't
Can
Can't
Can
Can't
Wake me when someone actually accomplishes something. I'm sick and tired or the back and forth debate over ethereal concepts that can neither be proven or disproven in our lifetime.
What was making impossible near-lightspeed travel? Only FTL was prohibited. Problems like engines, fuel, shielding etc. are only technological problems.
Where do I invest my Money?
For more information, see Dr. Felber's recent works on arXiv.org:
Weak 'Antigravity' Fields in General Relativity
Exact Relativistic 'Antigravity' Propulsion
Personally I'm a bit skeptical about his claims, however energy appears to be conserved. This method uses gravitationally-mediated kinetic energy exchange - this is the same principle that allows gravitational slingshot to work.
Wait, we can get close to light speed travel, but we cant figure out how to time travel?! This sucks.
Proudly posting without RTFA.
Um, except I need a star going more than 0.6c, passing close enough for me to whip in front of it... gee I hope this works....
One thing I have often wondered is if an object moves fast enough, could its relativistic mass become so large that it would look like a black hole relative to a laboratory frame?
Light-speed travel is impossible, but near-light-speed travel is wildly impractical, because of the mass you gain. This guy seems to be saying that if you have an anti-gravity machine, you could counteract that. You couldn't get to FTL, but you could go a lot faster than without it. Heck, there's all KINDS of nifty things you could do with an anti-gravity machine.
And if my grandmother had wheels, she'd be a wagon.
I think that this guy has been pushing his anti-gravity solution of general relativity for a while. IANAP, so I can't say whether he's right or wrong, though being a good skeptic I'm inclined to guess the latter.
"The White House is not an intelligence-gathering agency," -- Scott McClellan, Whitehouse spokesman.
Personally I'm waiting to see how they intend to get the moonbeams home in a jar...
You have to know the exact cause of gravity to negate it. Last time I checked they dont know what exactly adds to the weight of a single atom so I dont see how they can create antigravity.
What complete and utter nonsense. While I doubt I will see working antigravity in my lifetime (or if it is even possible at all), the idea that you must "know the exact cause" of something to manipulate it effectively is rubbish. Electromagnetic fields were not well explained until many decades after they had been successfully used in engineering applications (telegraph, lightbulb, radio). Even then it was much later that the much more accurate theory of Quantum Electrodynamics (widely considered to be the single most accurately tested theory in all of physics)...
Also you have to have good knowledge of the path involved. Imagine passing a asteroid 10m across at the speed of light. If your system cannot accomodate for the effects then most likely you'll be a smear inside the ship if the ship survives.
Ah ha, now there's a much more reasonable objection. The answer to this is simple - statistics. It's quite possible that near-lightspeed travel will be a tremendous gamble, one which will only be won by the use of massive redundancy. Instead of sending a single ship, we send hundreds or thousands, until one makes it. It's not like we're exactly running out of people any time soon.
Best bet is to hope that there's a nth demension you can pop into that allows you to travel the same spatime line without worrying about the mass of objects in the path.
That would be nice, but IIRC, there are no current theories that are either accepted or considered promising within the physics community that provide a mechanism for interdimensional transport using non-exotic mass/energy.
I dont see the two coming around anytime soon. It would be best to focus efforts on speedy travel between earth, mars, and the asteroid belt. Longer missions to the outer planets are fine but mars is our best bet for establishing a second colony of humans in case earth gets smeared by a large asteroid.
In 1900 people didn't see landing on the moon as coming any time soon, nevertheless it was written about and eventually studied. Our innate need to push the envelope in science and technology leads to many breakthroughs, intentional or not. More importantly it helps to inspire the next generation of scientists and engineers. When I interned at JPL, my supervisor said that that was the primary goal of NASA, and I believe it is a valid one.
Disclaimer: I am not a physicist, but I do have a B.S. in Physics.
- If you travel fast enough you can get as far as you like in as short a time as you like. There's an effect called time dilation. Maybe you haven't heard of it?
- Have you every tried to compute the distance you can cover assuming a constant acceleration of, say, a tolerable 2G. The distance you can get in a time t in your own frame of reference grows exponentially (well, hyperbolically cosinusoidaly which is much the same thing) with t because of time dilation. When you've mastered the physics required you may be pleasantly surprised by how far that distance is.
Methinks you know not of what you speak."The White House is not an intelligence-gathering agency," -- Scott McClellan, Whitehouse spokesman.
While antigravity is a cool SciFi story device, it is quite possible that attempting to implement an antigravity device is like pulling yourself out of the swamp by pulling at your own hair like Munchhausen, or like protecting yourself from rain by sitting in an open boat on a lake.
:-P), then you'd have to get in front of it, and in order to avoid the star smacking right into your spaceship, you'd have to have a speed of 0.57c already. Moreover(guessing), when you'd accelerate over 0.57c to take advantage of it, as you move away, the antigravity cone probably would loose focus and dispel just like gravity with a spread function of 1/r^2, quickly rendering it useless unless you'd just float along with the star.
r avity) predicts similar behavior on a small scale and provides a simpler model for working out strange gravity effects.
Now even when Dr. Felbers calculations are true, you'd first have to find a star speeding at a speed of 57%+ of lights speed(or accelerate one yourself
obLinks: Google "pushing gravity" or (http://everything2.com/index.pl?node=pushing%20g
I'm still trying to figure out what people mean by 'social skills' here.
Bussard ramjets are just cool and fine, and i liked the idea, too.
But the physics dont work out.
You get at most 2% or so of the mass converted into energy by the fusion process, even if you could fuse everything together perfectly efficient. But once your spaceship is moving quite fast (more than 10% or so of the speed of light), you will need to use more energy to move and collect the particles in your flightpath than you could possibly get by fusing them together.
It just doesnt work out if you look at the big picture.
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
Buick? You mean the size of a dust mote. If a dust particle weighs 1/100 of a gram, and you are going roughly the speed of light, the kinetic energy of the dust particle relative to you (assuming that the dust particle is roughtly standing still) is
.00001kg x (2.998 x 10^8 m/s)^2
898800400000 Newtons
9806 or so Newtons Per Ton
1,000,000 tons per MegaTon
20 Megatons per Hydrogen bomb
Thats 4.6 Hydrogen Bombs of energy that the dust particle has relative to you. Do you want to collide with 4.6 Hydrogen Bombs? I don't think that NLST is practicle, even if it turns out to be possible. What we need is a way to simultaniously transport stuff.
No, we have reduced to the problem of how to accelerate only part of the ship, while the other parts can hitch a ride on the first. I suspect the sweet spot would be the first part at 2/3 of the total mass.
If you're correct, then we're done:
--MarkusQ
Oh wait, I almost forgot:
There's a basic explanation of the known forces (Strong, Electronmagnetic, Weak and Gravity
n t Field,
There are quite a few ideas kicking about:
scalar-tensor-vector gravity (STVG)
Modified Newtonian Dynamics
General Relativity,
Quantum Gravity,
The http://www.halexandria.org/dward155.htm">Zero-poi
Superstring Theory,
M-theory,
Inflation/Cosmology,
Yilmaz gravitation, and
Membrane Gravity
Law of Universal Gravitation,
And there's also Intelligent Gravity
Unfortunately, there is no one simple experiment to prove any of these either true or false.
Vintage computer adverts: http://www.vintageadbrowser.com/computers-and-software-ads
You're stupid. Straight from the article:
More immediately, Felber's new solution can be used to test Einstein's theory of gravity at low cost in a storage-ring laboratory facility by detecting antigravity in the unexplored regime of near-speed-of-light velocities.
I take it you're not very familiar with Dr. Franklin Felber's extensive background and work.
I'll believe it when I see it.
Er, or maybe when I don't see it.
-S
--- What parts of "shall make no law", "shall not be infringed", and "shall not be violated" don't you understand?
The density of interstellar space is about one atom per cubic centimeter. If the spaceship were going near the speed of light (3 x 10^10 cm/sec), it would be hit by 3 x 10^10 relativistic particles per cm^2/sec. This is about the equivalent of one Curie per cm^2, which would kill a human and cripple any electronics on board
A very heavy magnet could deflect the protons, but the neutral atoms would be unaffected by the magnetic field.
Moving faster than 57.7% of c? Relative to what?
Right now, the earth is moving through space at a speed greater than 57.7% relative to something. No, I don't know what, or where, but rest assured there's some body out there somewhere in whose frame of reference the Earth is moving at greater than 57.7% of c. And there's some other body in whose frame of reference the Earth is moving at greater than 10% of c, and another body where Earth is moving at 95% of c, and another body where Earth isn't moving at all (Hey, like me!).
So why isn't the Earth emitting such an antigravity beam, repelling masses in its path? Rest assured that if it were, we'd be seeing its effect, like ferinstance as it played havoc with GPS satellites.
Or, heck, there are cosmic rays which occasionally smack into the Earth's atmosphere at a speed that's only infinitesimally smaller than c in Earth's FOR. They should *definitely* be emitting some sort of antigravity, if this guy's correct. Should be trivial to observe, but we haven't seen it.
This smells like bullshit.
Ok, I've worked in gravity for a while, but unfortunately I haven't time right now to go through this guy's paper. Several things are setting off my B.S. detector, though.
First, this guy is not a "noted" physicist, let alone a noted gravitational physicist, as far as I can tell. He published some papers in accelerator physics while affiliated with the Naval Research Lab. He has no publications, or as far as I can tell, training in general relativity. He's now affiliated with some company ("Starmark, Inc.") in San Diego. Furthermore, gravitational physicists generally give talks at gravity conferences (or at least physics conferences), not space engineering conferences (which have drastically lower standards when it comes to gravity, since the organizers of the conference typically have no GR background).
Second, I skimmed the preprint of his (unpublished) "antigravity" paper. He claims that a distant observer watching a particle fall into a black hole, in the (initial, local) rest frame of the particle, will see the black hole to approach the particle, and then cause the particle to accelerate away from the black hole. This is not in any weird "warp drive" spacetime, but in ordinary Schwarzschild spacetime — such as the spacetime outside of a star or a planet (!). Yes, you read that right, according to him, even planets create antigravity (if you're traveling fast enough). This bears no relation to anything I know about orbits of particles in Schwarzschild spacetime.
Then he mentions performing a Lorentz transformation of a particle trajectory into the frame of a distant observer. This is impossible. You can only apply a global Lorentz transformation to a flat (Minkowski) spacetime, not a curved spacetime (such as Schwarzschild). Well, you can apply a transformation to a flat tangent space at a point in a curved spacetime, but you can only transform a vector in the tangent space at that point, not an entire trajectory that spans a continuum of points. It is true that Schwarzschild geometry is asymptotically flat for "distant" observers, and he's speaking of transforming into the frame of a distant observer, but the fact remains that you cannot Lorentz transform a worldline that is not entirely within an approximately flat region of spacetime (and his trajectories definitely aren't always far from the gravitating body).
Now, you're free not to buy my suspicions, because as I said I haven't the time to go through all his calculations and see what's up (general relativity calculations are a pain in the ass). My bet, however, is that he's simply misinterpreting a coordinate quantity as having physical meaning. This is a common error for GR beginners (and you can see a prime example of it in the crackpot A. Mitra, who claims that black holes contradict the Einstein field equations based on his misinterpretation of coordinate derivatives in Schwarzschild spacetime). The thing about GR is that you can write solutions in any coordinate system you want, and you have to make sure that the quantities you're calculating are physically meaningful, and not just an artifact of whatever coordinates you happened to choose. Anyway, that's my guess based on what this guy has written so far and the kind of errors I see people make when making "wild" claims in GR. But it's also possible he simply made a math error. I am not betting, however, that he has suddenly discovered antigravity lurking within the ordinary Schwarzschild metric.
But interestingly, when I researched "Franklin S. Felber", I found conflicting dates for his degrees. At USC it says M.A. Physics, 1973; Ph.D. Physics, 1975. http://physics.usc.edu/Alumni/F.html. But the University of Chicago notes an alumnus Franklin S. Felber, SM'74. http://magazine.uchicago.edu/0304/alumni/works.htm l. Did he really get an MA in California in 1973 then a Masters in Chicago in 1974, then a PhD in 1975 in California?
How many Franklin S. Felbers are there? Perhaps he is well-known in some circles, and I could just be ignorant or mixed up. But I am getting the impression of an ambitious man here, and all that entails. Would someone who knows him well please straighten me out.
My fealing in the subject is that the speed of light is just a mental barrier.
Well, your feeling is wrong. There are very hard problems (i.e. all of Relativity) involved in making things go at lightspeed. The faster you go, the more you weigh - try getting around that.
"We returned the General to El Salvador, or maybe Guatemala, it's difficult to tell from 10,000 feet"
However, this is actually an underestimate since relativistic effects make it harder to get that close to the speed of light, the closer you get. If you could achieve a constant 1G, that is how long it would take, but this is physically impossible since effective mass increases with velocity.
I calculated it on Google calculator with the following formula (just type into search):
You make the assumption that the dust mote would actually stop, only then would the bulk of the KE go into the target space ship. More likely is that since the KE of each atom in the dust mote is so much larger than the atomic bond energy holding the grain together, the dust mote to the spacecraft really behaves like a very densely packed bundle of cosmic rays. If the spacecraft walls don't stop individual particles of that energy (ie like cosmic ray protons) then it won't stop the dust particle. The atoms would go in one side, out the other radiating a small fraction of their relative energy as gamma rays as cherenkov radiation and compton radiation. The dust would go out the other side as a diverging cone shaped spray of plasma.
That's bullshit. Theory is based on experimental evidence, and there is a century's worth of experimental evidence supporting relativity, including accelerating particles to enormous energies to within a tiny, tiny fraction of the speed of light. We find, just as relativity predicts, that as the particle's speed increases, additional inputs of energy give rise to less and less change in speed, so that its speed always asymptotically approaches that of light, never reaching it. First 99.999% of c, then 99.9999% of c, then 99.99999% of c, etc.
More nonsense. There are many things in science that are not merely "guesses" or "rough estimates", but rather are established beyond all credible doubt. There are guesses and rough estimates too, as well as things in between. (There is never proof in the mathematical sense, because it is logically impossible to prove a scientific theory 100%.)
That's also wrong. Scientists are encouraged to communicate with the lay public. You're simply not supposed to announce brand new results to the public before they've gone through peer review. Unfortunately, funding crunches have made "publication by press release" dismayingly common in recent years.
One quickly gets the idea that you not only don't know how science works or what it is, but you also don't know any scientists personally.
What the hell are you talking about? Nothing in science is totally authoritarian. There is nothing more contentious than a group of scientists arguing with each other about who's right.
Idiot. The word "law" as it is used in science does not imply that "laws" cannot have exceptions. Where did you get your knowledge of science, out of an elementary school textbook?
Regardless of what an individual scientist may claim, the truth of the matter is ultimately sorted out in the peer reviewed literature. That's the whole point of the scientific process: it's self-correcting.
Your are not the daring unconventional thinker you fancy yourself to be. In fact, kneejerk dismissal of perceived "authority" by self-proclaimed "freethinkers" is part of Slashdot groupthink. Intelligent people question claims (which has nothing to do with "authority"), but they also make sure they are informed, and you are not remotely informed about science, the scientific process, or the scientific community.
Time Dilation doesn't actually help much here. You have to accelerate to high speed and deccelerate at the end of the journey. Human beans can handle high accelerations for brief times with few ill affects, but we're talking months here. I suppose if you remain strapped into a squishy chair without having to move around too much then two or three g's might be more reasonable, but I'm pretty sure noone's done the studies.
Anyhoo, I typed "relativistic acceleration" into google, and two clicks later I was here.
It's a little disappointing. A traveller would only get up to 95% of the speed of light before it was time to start deccelerating. For longer trips, however, the effect would be greater.
Those people who think they know everything are a great annoyance to those of us who do. (Isaac Asimov)
Why the hell would we build near light speed weapons?
They would be more difficult to intercept.
They could be smaller, same kinetic energy yield for less mass.
You do realize we nearly have light speed weapons? Lasers. One of the benefits is that for practical purposes flight time from weapon to target is zero. No more having to lead the target. It makes interception of fast moving things far more practical.
Are you comfotable with the notion of time travel?
"The White House is not an intelligence-gathering agency," -- Scott McClellan, Whitehouse spokesman.
"An example of this is NASA's James Hansen. He speaks out directly to the public and is mobbed by his peers as a result. More power to him."
His peers DID NOT MOB HIM. Bush's fundamentalist political appointees are suppressing scientists all over the spectrum (as you know, of course). On global warming, reproduction, evolutionary biology, space science. Fundamentalist overseers and corporate lobbyists are running the show at all the agencies.
His peers have more to lose than Hansen does. Everyone is just waiting for the Democrats to take back the government so they can breath again.
I've often felt the same way about 2+2 never getting up to 5. Come on science, you can put a man on the moon but you can't get 2+2 even a decimal place past goddamn 4?
"Everthing else [in science] is simply theory. Which is based on some authority and never allowed to be questioned."
Wrong, wrong, wrong, and a thousand times wrong!
The whole basis of science is that everything is open to question. There are few things more prestigious in science than to refute a previously accepted theory. Ever heard of a guy named Albert Einstein? Yeah, thought you might have. Used to be that Newton's theories were the accepted way in which the universe worked, but Einstein showed differently.
The main reason it seems like some theories are "unquestionable" is simply because most of the ways in which people choose to challenge them have been shown time and time and time again to be false.
If you get 100 people a day proposing a design for a perpetual motion machine using a series of cogs, wheels, and magnets, you're not going to take the time to explain to each and every one why their design won't work, instead, you're just going to tell them to bugger off and leave you alone.
Of course, scientists are human, and at times they will reject things inadvertently which they shouldn't. However, if you think you have a good explanation as to how/why we can, in fact, travel faster than the speed of light, instead of whining to Slashdot about how stuck in the mud scientists are, why not publish it? You'd be the next Einstein!
Curiosity was framed. Ignorance killed the cat.
Replying to my own post, as I forgot to mention something else, and Slashdot's "edit post" button has undergone a total existence failure...
The parent also mentioned that scientific theory is based on authority. This is utter nonsense. Authority counts for nothing in science.
We accept Einstein's theories as being correct. Why? Because he was a really smart guy, and therefore must have been right? No. Because he showed exactly how and why his theories were correct.
If I tell you that water turns to ice or steam sometimes, and that's the way it is, because I say so, and because I'm smarter than you, then you'd probably tell me to get stuffed (and rightly so)
On the other hand, if I tell you that cooling water to 0C causes it to freeze into ice, and heating it to 100C causes it to boil, giving off steam, then you can try for yourself in your own kitchen. It doesn't matter if you think I'm a genius or a raving lunatic - it doesn't even matter if I actually AM a raving lunatic. The only thing that counts is whether it works or not. And the things we accept in science are those that work - and if we don't know, we run with our best current explanation based on the avaliable data until a better one comes along.
That's the wonderful thing about science. It's perfectly possible for some unknown, uneducated nobody with a bright idea to overturn hundreds of years of accepted science.
(of course, it's also rather unlikely, as the simple fact is the vast amount of unknown, uneducated nobodies who try to do that are completely off the mark, and don't have the first clue what they're talking about... doesn't mean it can't happen though.)
Curiosity was framed. Ignorance killed the cat.
Would the astronauts get paid for their local elapsed time or for the huge time that passes by on Earth?
One of the fundemental principles of logic is that you can not reduce the credibility of an argument by reducing the credibility of the one posing it.
In other words, 2+2 is not any more valid when posed by the pope than by Hitler. Or to go less concrete, Relativity would have been no more or less likely if Hitler has proposed it rather than Einstein.
Judge the good doctors ideas on their merits rather than on his merits.
So does it really matter whether "time itself" is slowing down or everything is simply going faster? To me, they're the same thing. Of course, the whole "backwards in time" thing is a bit iffy, but the main point of relativity is that time dilation and space contraction effects (as well as enegry stuff) approach infinity as the your speed approaches c. Whether these effects are "time itself" changing or just the way you see things doesn't really matter. The effects prevent you from going above the speed of light anyway. On that note, when people discovered that light was observed to move at the same speed in all reference frames, they tried to stick with the idea of ether, and put it a bunch of math that would account for the fact that light always travels at c. Well, all of this math eventually ended up being equivalent to relativity, as in, it made the same predictions. Your idea of "time itself", like the ether, is simply an artifact of your intuition. Your intuition was developed by observing things at small speeds moving relative to an absolute frame of reference (the Earth). As such, it is normal to expect that it might not apply in other environments, such as very high speeds, in the same way that your social experiences don't apply if you move to another country with a totally different culture. This is all assuming, of course, that you agree with the mathematics of relativity. Recall that special relativity assumes only a few facts, such as that light travels at c whatever reference fram you're in, and derives all the math from there. In order to disagree with relativity you'd need to either disagree with those facts (which have been experimentally confirmed, mind you), or disagree with the derivations, which have been checked and rechecked a bunch of times. Note also that relativity, especially special relativity, has a whole ton of evidence backing it up. Particle accelerators give electrons energies that, under Newtonian mechanics would put them well above c, but we observe them going no faster than c. The more energy you put in, the closer to c they go, but no matter how much you put in, the speed of the particle never surpasses c.