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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.'"
Why is an exotic solution involving anti-gravity even necessary, when there's the Bussard ramjet? While certain versions of this concept are infeasible, there's plenty of room for technical improvement. The ramjet has been a mainstay of science fiction for decades such as in Larry Niven's Known Space universe, precisely because it seems the solution closest to actual development.
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?
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.
Well, we have no problem running around in 1G for our whole live...
So weeks or months of acceleration wont hurt at all... in fact they would act as a convinient way of creating "artificial gravity" on the ship.
And even 1G adds up after a few days, and in a matter of a few months you are _highly_ relativistic.
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.
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
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.
Looks to me like a pretty good demonstration of how not to use weak field approximations. He appears to be describing something manifestly non-invariant which is just what you might expect from pushing the approximation too far.
"The White House is not an intelligence-gathering agency," -- Scott McClellan, Whitehouse spokesman.
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.
This is a great way to surprise an enemy that is light years away. Approach at close enough to light-speed, and the enemy will see you cross the last few light years of distance in just days, leaving them no time to prepare.
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.
"Einstein didn't just make up E=mc^2."
That's true, he didn't, it came from the formula E=MV^2 that was found by a French woman dropping steel balls into clay, it was a correction to Newtons erroneous E=MV. The C is just a constant V, Einstein got the idea because of experiments around the time had shown the puzzling result that light travels at the same speed in all directions.
Now when Einstien published his paper he assumed it was all just a mathematical curiosity, he did not think it translated to the physical Universe and was suprised when his papers were so enthusasticaly received. In other words Einstien made up a fundementally new physics that was such a "crackpot" idea that (for a while) he didn't belive it himself! He also kicked of the the crackpot field of quantum mechanics and then spent the rest of his life imploring others not to take it too seriously. Another example: The modern idea of an atom, literally came from a dream (the guy woke up with the crackpot idea that electrons orbit a nucleus), before then the most credible theory was that atoms looked like puddings with razor blades stuck in them.
Fundemental physics is not yet a "done deal", there are many gaping holes in our understanding and the recent (last decade or so) puzzling results labeled dark energy/matter have got a new generation of crackpots all fired up, dispite this vast army of crackpots across the globe, we still don't have enough of them to fill the holes and probably never will.
Anyway, I'm sure your not anti-science and I'm also reasonably certain the guy in TFA is a crackpot who has got it wrong but that's just my opinion. When you talk about science you need to rebutt the idea not the person, the fact they plucked a new equation out of their arse says nothing about it's validity. Luckily most crackpot ideas are so trivial to rebutt that scientists don't bother, some are harder and a paper or two gets published, some become accepted wisdom and it can take generations to spot the flaw, either way nobody has time to check them all.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
as you would be dead from starvation
This problem is handily defeated by human hibernation technology.
And I think we are closer to realizing that technology than near-light-speed spacecraft.
Yes you would be incredibly blue-shifted, but you would in fact appear to be coming in faster than light:
Suppose I fire a missile at you from 10 light-seconds away. If the missile is travelling at 90% of the speed of light, it'll take just over 11 seconds to hit you. You'll see it 10 seconds after I fire it, and the missile itself reaches you 1 second later. From your perspective, it looks & feels as though that missile was travelling at nearly 10 times the speed of light.
The same effect has been observed in space telescopes. Some black holes and other celestial bodies can emit jets of matter at significant fractions of lightspeed. If those jets are pointed in our general direction, they appear to be moving faster than the speed of light.
You look out your window. If you see that objects in front of you are being repulsed you must be travelling at c/sqrt(3). Being able to tell what your velocity is is a violation of relativity.
"The White House is not an intelligence-gathering agency," -- Scott McClellan, Whitehouse spokesman.
I've read somewhere that if you could maintain 1G of acceleration - speeding up for half the trip and then turning around and decelerating at 1G for the other half - you could basically reach anywhere in the universe within a normal human lifetime because of time dilation effects.
-- Give me ambiguity or give me something else!
Whatever you may personally think, he doesn't.
To an observer, the minimum time for another object to move from a point to another a light-year away is one year, yes; that's what makes c invariant. However, for the object moving, experinced time goes down asympotically as the speed of light is approached. If you were moving at c, you would experience literally no passage of time on the trip to Alpha Centauri from Earth, even though it would take you 4.3 years to an observer on Earth.
Another way to state it is that from the perspective of someone moving near the speed of light, the distance from Earth to Alpha Centauri shrinks; with the distance shorter, of course it takes less time to travel. However, the distance is still the same to the observer on Earth, and so the time for the trip as viewed by the observer is much longer.
(By the way, this is part of the reason why nothing can go faster than the speed of light; the distance between two points can't shrink to less than zero.)
This difference in space-or-time from different perspectives is why the theory is called relativity; space and time are not absolute constants for everyone evverywhere, but always exist relative to your reference frame.
Would the astronauts get paid for their local elapsed time or for the huge time that passes by on Earth?
From the point of view of the rock, all that would happen is that a solid object inside that spaceship is going to create a nice cylindrical hole in the nonmoving rock.
Come on, even a few electrons in vacuum that slam into a solid target at a velocity of c/2 (about 10^5 eV) will generate loads of X-rays by kicking out electrons that are in the deepest shells inside the atoms. With heavier particles such as atomic nuclei, the electrons around the nuclei will certainly not be able to keep the projectile nuclei out. It is likely that you will get some nuclear reactions as the atoms constituting the rock literally go through the atoms constituting your spaceship.
Avantslash: low-bandwidth mobile slashdot.
Well, there's something about "Mach's Principle" that I don't believe has ever been untangled. But I think that only applies to rotational velocity. (I.e., what makes you think you're rotating rather than still?) I think he asserted, approx., the entire rest of the universe dragged your frame. Mach's Principle
I think we've pushed this "anyone can grow up to be president" thing too far.