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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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  • Re:Fuckin' Noobs (Score:5, Informative)

    by captaindomon (870655) on Wednesday February 17, 2010 @11:41AM (#31171002)
    Not to mention the Bussard Collectors.
  • by JamesP (688957) on Wednesday February 17, 2010 @11:57AM (#31171346)
  • by Space cowboy (13680) * on Wednesday February 17, 2010 @12:01PM (#31171426) Journal
    Let me recap for you (both of the below points taken from the links I provided...):

    1) Proposed by the physicist Miguel Alcubierre, popularised by Star-Trek.

    2) Proposed by the physicist Robert W Bussard (hence "Bussard Ramjet"), popularised by Larry Niven (the author), and even referred to by Carl Sagan on TV and in books...

    Various other authors have used the same ideas. Perhaps I ought to have mentioned that I'm a physicist too... And the gentle humour regarding tense was supposed to clue you in that I wasn't suggesting we had a practical solution just yet... I wish I'd spelt "two thoughts" correctly, though.

    Simon
  • by Rockoon (1252108) on Wednesday February 17, 2010 @12:04PM (#31171492)

    Sure, it seems infinitely fast, but it's really not going to get us anywhere all that interesting in a single lifetime.

    For the personal traveling at that speed, it most certainly WILL be a single lifetime. In fact, the trip would seem to them to be instantaneous.

  • Re:Oh noes (Score:5, Informative)

    by NatasRevol (731260) on Wednesday February 17, 2010 @12:27PM (#31171968) Journal

    10% of the speed of light is 67 million miles per hour.

    Helios 2 - fastest manmade object ever - went about 150,000 mph.
    http://www.aerospaceweb.org/question/performance/q0023.shtml [aerospaceweb.org]

    So, yeah even 1% of the speed of light would be 40x faster than anything else we've ever done.

  • Re:old news... (Score:4, Informative)

    by Geoffrey.landis (926948) on Wednesday February 17, 2010 @12:39PM (#31172210) Homepage

    They already figured this out nearly a hundred years ago.

    In fact, erosion by interstellar matter (both hydrogen and dust) was a major plot element in Arthur C. Clarke's 1986 novel The Songs of Distant Earth.

    A while back, at the old 1994 Planetary Society conference on Interstellar Flight, I had a paper proposing a plasma erosion shield to protect an interstellar spacecraft-- I ought to dig that one up and put it on the web somewhere, but New Scientist ought to know about it, since they mentioned it in an article [newscientist.com] back in 1995.

  • by fatmonkeyboy (257833) on Wednesday February 17, 2010 @12:45PM (#31172310) Homepage
    You are completely and absolutely wrong. Are you getting him confused with someone else? Asimov studied for and received his Ph.D. in biochemistry the standard way. He then worked for the Navy during WWII as a chemist and was later a professor of biochemistry at Boston University. I know all of this because I was a huge fan as a kid (and read his autobiography multiple times). But here's the wikipedia article: http://en.wikipedia.org/wiki/Isaac_Asimov [wikipedia.org]
  • Re:Oh noes (Score:4, Informative)

    by blueg3 (192743) on Wednesday February 17, 2010 @12:50PM (#31172408)

    For large objects, that is. We regularly accelerate small particles to large fractions of lightspeed.

  • by Lumpy (12016) on Wednesday February 17, 2010 @12:52PM (#31172452) Homepage

    we can also ignore the fact that the Parts worked perfectly, it's the SOFTWARE that was screwed up. That was made by Toyota, tested by toyota, and Approved by toyota.

    As to the GP, GM "pieces of shit' are mostly china parts assembled in mexico or Canada. You cant buy an American car anymore. They dont exist.

  • Re:Fuckin' Noobs (Score:5, Informative)

    by rssrss (686344) on Wednesday February 17, 2010 @01:01PM (#31172636)

    The Bussard Collector is part of a Bussard Ramjet [wikipedia.org].

    The Bussard ramjet is a system of spacecraft propulsion proposed in 1960 by the physicist Robert W. Bussard. A moving spacecraft would use enormous electro-magnetic fields to collect and compress hydrogen from the interstellar medium. The hydrogen would be forced into a progressively constricted magnetic field, which would compress it until thermonuclear fusion occurs. The magnetic field would then direct the heated gas in the direction opposite to the intended direction of travel, thereby accelerating the vessel.

    More generally [wikipedia.org].

  • by Artifakt (700173) on Wednesday February 17, 2010 @01:05PM (#31172732)

    Asimov worked specfically as a Munitions Chemist in WW2, alongside several other SF authors, including E. E. "Doc" Smith. Some of Isaac's war era work was classified well beyond that time (T.S. - 50 year to review at one time, according to Freedom of Information Act requests) and now seems to have become a matter of rumor and fallen from the official records, part of an interesting bunch of mostly unconfirmable claims suggesting that he, R A Heinlein, Jack Williamson, and maybe several other SF authors were consulted with regard to the Manhattan project just before Truman was informed. While that appears to be undocumented, There are Heinlein's own printed remarks about having two positions in the war, one of which he could talk about, and Larry Niven's comparison of what he and Jerry Pournelle did in advising the Bush administration after 9/11 to what a group of unspecified SF writers did in WW2, to make the rumors at least a trifle plausible.

  • by dmartin (235398) on Wednesday February 17, 2010 @01:35PM (#31173304)

    It really depends on what you think is relevant. For example if the purpose is to do research for people on Earth, you probably are interested (at least in part) in the time taken for the round trip, and how long people on Earth have to wait to see the benefits of their investment. If you are looking at colonization then you are probably more interested in the amount of time as experienced by the people travelling on the ship. In this case the difference between 99.9% of the speed of light, and 99.99% of the speed of light is significant.

    To make the example concrete, let us take your example of Alpha Centuri:
    Distance: ~ 4 light-years.

    • 99.9% of the speed of light:
      Time (Earth observer): 4 years and 1.5 days
      Gamma factor*: 22.4
      Time (Ship observer): 65 days
    • 99.99% of the speed of light:
      Time (Earth observer): 4 years and part of a day.
      Gamma factor*: 70.7
      Time (Ship observer): 20.5 days.

    So from the point of view of the *crew* the journey takes about a third the time, although from Earth you are correct in stating they are essentially the same.

    * The gamma factor, or time dilation factor (or length contraction factor), is given by special relativity. If you speed is v and the speed of light is c then
    Gamma factor = 1/sqrt(1-(v/c)^2)

  • by Angst Badger (8636) on Wednesday February 17, 2010 @01:36PM (#31173322)

    For relatively local trips, the difference amounts to a triviality

    For relatively local trips, especially considering that you have to spend half the trip turned around and decelerating, there's going to be a point well before nine-tenths of C that the cost of further acceleration vastly outweighs the value of getting to the destination faster. Without knowing what the cost of energy is going to be if and when we can build propulsion systems capable of relativistic travel, I couldn't say where the point of diminishing returns would be, but for in-system travel, I'd be willing to bet it's not even an appreciable fraction of C.

    Besides, it's a long, hard slog to Vland.

  • Re:old news... (Score:2, Informative)

    by Marsala (4168) on Wednesday February 17, 2010 @01:57PM (#31173690) Homepage

    Yeah, it's kind of hard to find something with which to relate.

    Maybe... "For the crew, it would be like getting ganked by 7,000,000,000,000 retadins (or 7 terarets) in WoW, all at once."

  • by microbox (704317) on Wednesday February 17, 2010 @02:39PM (#31174434)
    Actually you are missing something very important in your maths: relativity. It doesn't take much shorter to get to the destination from the perspective of someone on earth, but the tale is different for the people on the spaceship. The distance to the destination shrinks.

    Sagan talks about this in Cosmos. If a theoretical spaceship accelerated constantly, it could traverse the entire universe in a mere 50 years -- but by the time it returned earth would be long gone.

    Conceptually -- the universe has no "size" for a photon in a perfect vacuum. From the point of view of this theoretical photon, it is created in a distant star and intersects with your eye instantaneously. From our point of view it could take millions of years.

    Considering that mass is what prevents light-speed travel (as well as the density of the medium being travelled through), that implies an interesting relationship between space-time and the higgs boson.

    The universe is stranger than any fiction.
  • by Daniel Dvorkin (106857) * on Wednesday February 17, 2010 @03:36PM (#31175452) Homepage Journal

    Remember, before Bell Aircraft came along and just did it, scientists opined that breaking the sound barrier was impossible too.

    No they didn't. It was understood since the nineteenth century that the "sound barrier" was an engineering problem, not a scientific one.

  • Re:old news... (Score:3, Informative)

    by exploder (196936) on Wednesday February 17, 2010 @03:38PM (#31175488) Homepage

    Not to mention, does that comparison mean anything to anyone else? I've never stood in front of the LHC personally and don't know anyone who has.

    Talk to this guy [wikipedia.org].

  • Re:Fuckin' Noobs (Score:3, Informative)

    by Weedhopper (168515) on Wednesday February 17, 2010 @04:42PM (#31176560)

    The guy is a prof in a Medical school. What does he know about physics!?

    Because the guy's a Harvard trained PhD physicist with relevant research interests, who also happens to be teaching at the Department of Radiology at Hopkins, that's why.

  • Re:Fuckin' Noobs (Score:3, Informative)

    by bill_mcgonigle (4333) * on Wednesday February 17, 2010 @04:51PM (#31176692) Homepage Journal

    Star Trek? Bussard Ramjets were popularized by Larry Niven [larryniven.org].

    Yes, this thread started on deflector dishes, a 'trek tech. Then Bussard Collectors were added in a reply, also a 'trek tech. They're not funneling the hydrogen at speed into a fusion reactor, merely collecting it, but they do use it to mitigate the interstellar gas pressures that are the subject of TFA.

    If you really want to split hairs, Tau Zero pre-dates the Niven works by a few years.

  • Re:Economics (Score:3, Informative)

    by BZ (40346) on Wednesday February 17, 2010 @07:01PM (#31178440)

    > You don't need to go anywhere near lightspeed

    The grandparent specifically said constant 4g boost to Alpha Centauri. That ends up near lightspeed.

    But even if you restrict to just getting there in "years" (as great-grandparent did), you end up with an average speed of close to 0.5c if you want to stay under 10 years... Which means your top speed needs to be pretty close to c.

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