Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

I Intergalactic space

  1. Sep 11, 2016 #1
    Upfront: I have no formal training.

    While the distances of interstellar space are forbiddingly huge, the distances between galaxies would seem to be impassable for any life form, no matter how advanced, barring (very) theoretical traversable wormholes.

    Aside from radiation and the tyranny of distance, I'm wondering if another hazard of intergalactic space might be the effect on time in zones of space far removed from our familiar gravitational fields. Given that time slows in high gravity areas like black holes, would it follow that accelerated ageing could be as issue for any entity - biological or otherwise - that finds itself in intergalactic space?
  2. jcsd
  3. Sep 11, 2016 #2

    Filip Larsen

    User Avatar
    Gold Member

    If you compare interstellar space with the surface of normal planets where life can be expected to exists, then I would say no.

    For instance, if you include the gravitational field of the Sun and Earth then time dilation [1] will make the year around 487 milliseconds shorter on the surface of Earth per year compared to interstellar space (465 ms from being in a circular orbit around the Sun and 22 ms from being on the Earths surface). It will be a measurable effect, but not one I can imagine being significant for aging.

    [1] https://en.wikipedia.org/wiki/Gravitational_time_dilation
  4. Sep 11, 2016 #3
    Thanks Filip. To check my understanding, barring time-sensitive equipment like GPS, time dilation differences in space are only significant as regards the extreme gravity of black holes.

  5. Sep 12, 2016 #4


    User Avatar
    Science Advisor
    Gold Member

    You could toss neutron stars into the mix, they have pretty deep gravity wells
  6. Sep 12, 2016 #5

    Filip Larsen

    User Avatar
    Gold Member

    If you are still talking about aging, then it is difficult to imagine that gravitational time dilation would be a significant problem for the general population of a interstellar civilization. However, it is not difficult to imagine an interstellar civilization having "social" issues with time dilation due to high speed travelling, a subject often explored by science fiction writers. I guess it really comes down to what underlying situation you have in mind with your question.
  7. Sep 12, 2016 #6
    Cheers Chronos. Wiki tells me that time dilation on a neutron star is significant, but not profound, the example given being: "eight years could pass on the surface of a neutron star, yet ten years would have passed on Earth, not including the time-dilation effect of their very rapid rotation".

    Not interstellar space, Filip, intergalactic space. Whatever, the distinction in context is probably moot. My initial misconception seemed to be imagining intergalactic space to be significantly less empty than interplanetary or interstellar space. The impression I now have is that all of space - interplanetary, interstellar and intergalactic - is very empty (speaking as a denizen of a massive planet), with total energy per centimetre small enough to be measured in ergs.

    I was naively imagining intergalactic space to act like a reverse black hole, in which one ages and dissipates in an instant due to an almost complete lack of gravity. I can now see that the accelerated ageing effect described would logically be the effect near a theoretical white hole, that would be separated from the universe by an event horizon in which nothing within the universe can enter.

    Thanks to you and Chronos for helping to clarify.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted