Near Light Speed Travel Possible After All? 539
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.'"
Comment removed (Score:2, Interesting)
Go fast enough to look like a black hole? (Score:4, Interesting)
Re:Pretty cool but useless (Score:3, Interesting)
There is no antigravity device to take along (Score:3, Interesting)
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
Re:WTF? (Score:5, Interesting)
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.
Re:Stopping (Score:5, Interesting)
.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.
Re:Missing Something (Score:3, Interesting)
There are quite a few ideas kicking about:
scalar-tensor-vector gravity (STVG) [newscientistspace.com]
Modified Newtonian Dynamics [umd.edu]
General Relativity [uiuc.edu],
Quantum Gravity [cam.ac.uk],
The http://www.halexandria.org/dward155.htm">Zero-poi
Superstring Theory [superstringtheory.com],
M-theory [cam.ac.uk],
Inflation/Cosmology [cam.ac.uk],
Yilmaz gravitation [wikipedia.org], and
Membrane Gravity [hesston.edu]
Law of Universal Gravitation, [tripod.com]
And there's also Intelligent Gravity [bringyou.to]
Unfortunately, there is no one simple experiment to prove any of these either true or false.
The travelor would die from radiation (Score:5, Interesting)
The density of interstellar space is about one atom per cubic centimeter [hypertextbook.com]. 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 [wikipedia.org] 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.
Re:Has Slashdot become crackpot central? (Score:2, Interesting)
Huh? (Score:5, Interesting)
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.
Re:Make sure you account for everything (Score:3, Interesting)
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.
Comment removed (Score:5, Interesting)
Re:Has Slashdot become crackpot central? (Score:3, Interesting)
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.
Re:Make sure you account for everything (Score:3, Interesting)
This problem is handily defeated by human hibernation technology.
And I think we are closer [scienceblog.com] to realizing that technology than near-light-speed spacecraft.
Re:Make sure you account for everything (Score:3, Interesting)
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.
Re:Has Slashdot become crackpot central? (Score:3, Interesting)
Re:Time Dilation: Not a Panacea (Score:3, Interesting)
Re:Make sure you account for everything (Score:5, Interesting)
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.
Re:There is no antigravity device to take along (Score:3, Interesting)
You're not building an antigravity device. The star acts as an 'antigravity' device, which is a crappy name for it anyway. Just think of it as "forward frame dragging". If a massive object travelling close to c moves close to you, it drags your frame of reference violently along with it. You're "riding its wake."
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
That, of course, is the key. Which... you won't find, as I don't think there's any astrophysical object travelling at 0.57c towards any other object. That'd be a ridiculously high peculiar velocity [wikipedia.org].
and in order to avoid the star smacking right into your spaceship, you'd have to have a speed of 0.57c already
Nonono - it's a cone in front of the star. So off-axis of the star's path, it'll still push objects. Directly on-axis to the object, they'll collide. They have to. We already collide objects at greater than 0.57c relative velocity.
This should be easy to check, as the article does say. Your immediate reaction might be "wait, we should know this, then, from particle accelerators."
Curiously enough, that's not true - we don't look at the forward region of particle collisions, because, well, it's not interesting to particle physics. Only the extreme off-axis particles have a ton of available energy to produce particles, and so we basically don't look at the forward particles at all.
There's an experiment (LHCf [particle.cz]) planned for the LHC to look at this. Why? Because, curiously, there's another area of physics that seems to say "hey, we might not understand the extreme forward physics very well...": cosmic ray air shower simulations, which currently don't agree that well with actual experiments.
One wonders if this effect might actually be the cause of that disagreement...
Overtime (Score:2, Interesting)
Re:WTF? (Score:3, Interesting)
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.
Re:The subjunctive case (Score:3, Interesting)