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Interstellar Hydrogen Prevents Light-Speed Travel? 546

Posted by CmdrTaco
from the einstein-brought-in-backup dept.
garg0yle writes "As if relativity wasn't enough to prevent us traveling at light speed, Professor William Edelstein of the Johns Hopkins University School of Medicine is now claiming that the interstellar hydrogen, compressed in front of the ship, would bring the journey to a shocking end. 'As the spaceship reached 99.999998 per cent of the speed of light, "hydrogen atoms would seem to reach a staggering 7 teraelectron volts," which for the crew "would be like standing in front of the Large Hadron Collider beam."'"
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Interstellar Hydrogen Prevents Light-Speed Travel?

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  • by BubbaDave (1352535) on Wednesday February 17, 2010 @01:07PM (#31171564)

    Perhaps not those specific things, but...

    http://www.technovelgy.com/ [technovelgy.com]

    "Explore the inventions and ideas of science fiction writers at Technovelgy (that's tech-novel-gee!) - over 1,865 are available. Use the Timeline of Science Fiction Invention or the alphabetic Glossary of Science Fiction Technology to see them all, look for the category that interests you, or browse by favorite author / book. Browse more than 2,770 Science Fiction in the News articles. "

    Dave

  • by delt0r (999393) on Wednesday February 17, 2010 @01:12PM (#31171632)
    Some numbers! If the ship is just 100kg with cargo, then you need 6.36e22 J to get to .99999998c assuming 100% efficiency. About 1.4e21 J hits earth everyday from the sun. So a earth sized solar panel will collected the energy required in about 4 and half days. All assuming no energy losses.
  • The Galactic Patrol (Score:2, Interesting)

    by UberMunchkin (1106101) on Wednesday February 17, 2010 @01:15PM (#31171722)
    Didn't E.E Smith talk about this years ago in the Lensman books. I'm pretty sure the Galactic Patrol moved on tear-drop shaped warships over their original spheres purely because their intertialess drive allowed them to move so fast the the occurrences of interstellar hydrogen atoms began to act on the hulls as friction and slowed them down.
  • by Maximum Prophet (716608) on Wednesday February 17, 2010 @01:17PM (#31171758)

    Seriously, any number of sci-fi authors have covered this problem in enormous detail over the last few decades

    Yes, any number of sci-fi authors have handwaved around these problems for the last few years. Actual scientists, not so much. And, as with TFA, the conclusions of the ones that have been less than sanguine. (From the POV of actually doing it.)

    Robert W. Bussard (August 11, 1928 – October 6, 2007) was an American physicist who worked primarily in nuclear fusion energy research. He was the recipient of the Schreiber-Spence Achievement Award for STAIF-2004.[1] He was also a fellow of the International Academy of Astronautics.

    See also, Bussard ramjet http://en.wikipedia.org/wiki/Bussard_ramjet [wikipedia.org]

    Without a ramjet, you'd probably run out of fuel before reaching 99.999998 per cent of the speed of light.

  • by Graff (532189) on Wednesday February 17, 2010 @01:24PM (#31171922)

    I wondered why they didn't run them in series. Cumulative thrust would have put the ship closer to light speed.

    Not necessarily. You are actually fusing those hydrogen atoms, turning them into helium. The output of one ramjet has less hydrogen than went into it. Yes, you could fuse that hydrogen/helium exhaust into heavier elements but it won't release as much energy. Basically you'll be adding mass to your spacecraft by putting another engine on but you won't be increasing your thrust as much as you may think.

    You might eke out a bit more acceleration with another engine in series but it's probably not worth it. You don't want to put them in parallel on a small ship either, for several reasons. For example, the magnetic fields that funnel material into the engine are supposed to extend in a cone far in front of the engine. Two engines that are close together will have their magnetic fields interact, complicating the management of those fields. Another concern would be properly adjusting those engines to maintain even thrust on both sides. When you're traveling at a significant fraction of the speed of light a slight variation in the hydrogen input of one engine could tear apart your spaceship pretty easily.

  • my proposition (Score:3, Interesting)

    by corbettw (214229) <corbettw@@@yahoo...com> on Wednesday February 17, 2010 @01:24PM (#31171924) Journal

    There's an old saying, nothing focuses the mind like a firing squad. When faced with imminent death, humans are famously adept at coming up with novel solutions to complex problems. To that end, I propose we gather a collection of prominent physicists and place them in a ship capable of accelerating to near-light speed over a period of some years. Put locks on the controls so that they are unable to halt or alter the acceleration, then inform they have X years to come up with a way to avoid being smashed to death by interstellar gasses. Either they come up with a solution and are all saved, or they perish in a fiery ball of glory. Either way, they'll probably all have high schools named after them.

  • by DerekLyons (302214) <fairwater AT gmail DOT com> on Wednesday February 17, 2010 @01:30PM (#31172022) Homepage

    And if you actually read the Wikipedia article you link to, rather than just drooling over the qualifications of the inventor, you'll find that as people have actually began to seriously study it - there are now significant doubts as to how well it will work. (Even assuming we figure out how to do the parts Bussard handwaved into existence, like the magnetic scoop.) In addition, even if it does work, it may be subject to the problems outlined in TFA.

  • by InterGuru (50986) <jhd.interguru@com> on Wednesday February 17, 2010 @02:20PM (#31173050) Homepage

    http://science.slashdot.org/comments.pl?sid=177080&cid=14696574 [slashdot.org]

    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:old news... (Score:3, Interesting)

    by rpresser (610529) <`moc.liamg' `ta' `resserpr'> on Wednesday February 17, 2010 @03:08PM (#31173884) Homepage

    Is this it, Dr. Landis?

    http://www.islandone.org/Settlements/MagShield.html [islandone.org]

    Magnetic Radiation Shielding: An Idea Whose Time Has Returned?
    Geoffrey A. Landis

    Presented at the Tenth Biennial SSI/Princeton Conference on Space Manufacturing
    May 15-19, 1991, Princeton, N.J.
    posted with permission of author

  • Re:Economics (Score:3, Interesting)

    by BZ (40346) on Wednesday February 17, 2010 @03:18PM (#31174062)

    > I don't think that accelerating a shuttle-sized craft at 4 or 5g requires the current
    > total energy consumption of humanity

    Let's call it 4g in the spacecraft's frame, or a force of 4g*m (rest mass). Doing a quick special-relativistic approximation to the process, I get:

        v = c * tanh(4gt/c)

    as the spacecraft's velocity in the earth's frame as a function of time. Then its position is:

        s = c^2/(4g) * ln(cosh(4gt/c))

    or in other words:

        cosh(4gt/c) = exp(s*4g/c^2)

    Plugging in s = 2.19 ly (half the distance to Alpha Centauri) we get:

        t = 2.36 years

    or so. At that point you turn over and start decelerating.

    The peak power draw in this setup will be at this t=2.36 year mark, at which point we have v = 0.99999999c if my calculations are right. dE/dt = mva*gamma or so. Gamma is 8500 or so in this case. So we're looking at about 1e14 watts per kilogram. The space shuttle's mass is about 2e6 kilograms, so you're talking 2e20 watts.

    World average power consumption in 2008 was 1.5e13 watts according to . So in fact peak power draw for your proposed constant-4g trip would be about 10,000,000 times more than the power consumption of all of humanity today.

    Never underestimate the energy of macroscopic objects traveling at near-lightspeed.

  • by Tetsujin (103070) on Wednesday February 17, 2010 @03:40PM (#31174446) Homepage Journal

    One of those classic complaints against popular sci-fi is that the ships are always pretty and "aerodynamic" (well, mostly, anyway) and that there's no need for this in a vacuum... Well, there you go, one good reason to have aerodynamic space ships. :)

    Making spaceships sleek was a key part of making them fast in the Lensman books for more or less the same reason. (Smith's goofy FTL drive idea negated the mass of the ship, allowing the ship to instantly accelerate to a speed where thrust equaled drag)

  • by amorsen (7485) <benny+slashdot@amorsen.dk> on Wednesday February 17, 2010 @04:51PM (#31175740)

    Accelerating to 99.999998% of light speed in 3.5 hours would be a somewhat dizzying experience. Especially since you'd actually experience an acceleration equivalent to going to 5000 times light speed in a pure Newtonian universe. We're talking more than 500.000km/s^2 here -- or 50 million g.

  • by arminw (717974) on Wednesday February 17, 2010 @05:55PM (#31176744)

    ....We need warp drive, subspace, wormholes, or something else ....

    All of the posts on this subject make the assumptions of a Western scientific/materialistic worldview. There are other views, such as the Bible for example, which open other possibilities for exploring the universe.

    The first and foremost problem to overcome is physical mortality. Jesus Christ claimed to be God and proved this claim by overcoming death. As far as I'm concerned, that would be a prerequisite to being able to explore the vast universe.

    The second problem is to get rid of the limitation of mass. This means that a complex material spaceship would not be needed, in order to leave the earth for other worlds. Read the account of the ascension of Jesus Christ. He did not need a fiery rocket or other kind of vehicle to simply depart the surface of the earth to travel to another world.

    Science has conditioned us to only think in terms of the physical, material part of reality. Einstein taught us that the speed of light is a physical limitation because of energy and mass. He also taught us that matter and energy are directly interchangeable. He had nothing to say on the speed of thought. Does gravity have a speed limit and could it be reversible given the right conditions? We read in the Bible about God and the spirit world and its inhabitants of demons and angels. These cannot be perceived by science. Does that mean they don't exist?

Swap read error. You lose your mind.

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