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Relativistic Space Matter Flows over near light speed ships

  1. Apr 9, 2012 #1


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    Does anyone know if any work, no matter how speculative, has been done on the following:

    Assume a ship (or any vessel) travels through space with a Gamma of 10-100. As the ship travels through the interstellar medium, there is a constant barrage of nuclear explosions over the tip of the jet as interstellar particles slam into the jet. Is any other detail further speculated on this? Would the resulting nuclear explosions form any kind of streamlines (obviously I mean of exotic, high energy particles here not air particles), shock waves, bow waves, etc. analogous to air flows over a regular airplane? Would there be any patterns resulting from the by-products of reactions with the high-energy reactions of the light speed jet and interstellar space gas?

    Ok if this is too far advanced or out there, but I searched for a long time on the internet and couldn't find anything, and just wanted to check.

    I did searches on "relativsitic fluid dynamics", but that field has more to do with gases around stars and black holes.
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  3. Apr 9, 2012 #2
    Hmm, I've never thought about that. Assuming you were traveling fast enough for such reactions to occur, I would venture to guess that the density of particles in the medium is far too small for visible reactions to happen. Rather I would say you would just get small bursts of energy towards the front of the ship, but nothing explosion-y.

    Thats just my guess though, someone might know otherwise.
  4. Apr 10, 2012 #3
    Umm.... why would there be nuclear explosions?
  5. Apr 10, 2012 #4
    There is the idea of the Bussard Ramjet.


    Science fiction authors Larry Niven and Poul Anderson (in a great book called Tau Zero) used the idea.

    A very large, very powerful electromagnetic field is used to funnel ionized interstellar hydrogen to a point where fusion occurs, supplying the power to propel the ship.

    If you read the wiki article, you'll see that it's not really feasable. At the time of the proposal, the density of interstellar hydrogen was thought to be much higher than it is.

    But while it won't work as an energy source, it might work simply as a 'shield'.
  6. Apr 10, 2012 #5
    Impacts with particles will be like impacts from a high velocity bullets and will almost certainly cause a lot of erosion of the nose. The best place to look for any info will to be look for research on the high energy jets that are observed to emanate from the poles of black holes at relativistic speeds and interact/collide with surrounding space dust and gas clouds. I imagine an additional problem with travelling at very high relativistic speeds is that any background light will blue shifted into the x-ray and gamma region passing through the nose of the ship and radiating the occupants.
  7. Apr 10, 2012 #6


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  8. Apr 11, 2012 #7


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    Hi all,

    It took a few days, but I can answer zhermes at least. I'll soon look at the other references.The quote:

    "Umm.... why would there be nuclear explosions?"

    Yes, it turns out you are right in that for low relativity, but in a region of high density gas there could be nuclear bombs. Here's what I did, very roughly:

    Assume a space shuttle with a flat bow, normal vector parrallel to direction of travel. Diameter is 5.0 m, ship flies at V≈c no matter what γ is, but take γ=20. Space shuttle will travel ≈3(10^8) m in one second. The space shuttle will sweep out a volume of 2.36(10^10) m^3 in this time.

    How many particles will the space shuttle impinge in this one second of flight through interstellar medium? Let density of atoms be 10 atoms/cm^3, assume mostly Hydrogen, so this is 10 amu/cm^3. In the space shuttle's rest frame, the ship is at rest, and the interstellar particles move at it with, γ=20, E=γmc^2 or (let m= 1amu), 3(10^-9) Joules.
    Assume all energy of atoms is transferred to space shuttle on impact. We have 10 million atoms per cubic meter, each atom has 3(10^-9) Joules, in a volume of 2.36(10^10) m^3, and we multiply those three numbers together for a grand total of 7.1(10^8) Joules for one second of flight. This is about a bolt of lightening. Thus, I agree with

    "But while it won't work as an energy source, it might work simply as a 'shield'.

    A lightening bolt every second in space isn't much, but it would need to be shielded against for any ship. My estimate would be low, but I would expect the main energy contribution to be nuclei in space; I expect the e-s and photons would contribute much less. I don't know what the photon density would be in deep space, but its got to be much less than we get from the sun, which isn't much at all, and I assume one e- for every amu, where the mass of one e- is insignificant to the mass of a proton.

    On the site: http://en.wikipedia.org/wiki/Orders_of_magnitude_(energy [Broken])

    We see that the smallest atomic bomb worth of energy is about 10^13 Joules, or 4 orders of magnitude larger than lightening.

    To get up to an atomic bomb per second, it seems the only easy thing that could be done would be to fly through a denser region of space (10^5 atoms/cm^3). Increase γ to 10^4 is impossible even by current sci-fi standards, and I can't make the cockpit area increase to 10^4 times its size.

    This was a good exercise. Even though most likely it will be a lightening bolt of energy per second, there still could relativistic fluid flows on a near light speed ship similar to air flow around a jet flying through the atmosphere. Through high density gas, one could get nuclear explosions.
    Last edited by a moderator: May 5, 2017
  9. Apr 16, 2012 #8
    Re: What is the effect of relativity space travel, or cold on atomic decay.

    Not being to bright, what I have wondered about, is the actual age of atoms coming in from interstellar space to earth and the new arriving matter, dust, gas, meteors, et al, (to include the original mass of our sun, planets, et al), if, or not they have been effected by the relative travel speed and/or, the gross cold of space on the expected decay of the mass. It to me seems that most mass should be ether gone by decay, or reduced to the fuzzy left over mass of the more durable atoms. Considering the distance travailed, the time involved, it seems to me that by the general known, half life decay, the masses atoms should be about done and gone, yet are not, does the relative mass speed slow the half life decay, or does the gross cold slow the half life decay, or do I simple have my ideas and knowledge wrong. Xtrapper@hotmail.com
  10. Apr 16, 2012 #9
    Re: What is the effect of relativity space travel, or cold on atomic decay.

    You are right, relativistic time dilation slows the decay of particles the same as everything else. The very fast matter is in the form of individual particles because the processes launching them at such speeds break apart anything larger and since temperature is a measure of the relative motion within a group of particles, it doesn't have an effect.
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