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

Farthest stars and velocity

  1. Jun 4, 2014 #1
    Stars and galaxies that are further away from us are moving away faster, based on the red shift. What is the relationship between the maximum velocity of the furthest ones, as a fraction of the speed of light, and the mass of the universe? If we extrapolate the velocity up to the speed of light, what does that give, hypothetically, for the mass?
     
  2. jcsd
  3. Jun 4, 2014 #2

    PeroK

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Galaxies that are far enough away are receding from us faster than the speed of light.
     
  4. Jun 4, 2014 #3
    [tex]V=Hd[/tex] where v is the recessive velocity. Hubble's law states the greater the separation distance the greater the recessive velocity. So objects past a certain point called the Hubble's sphere objects will recede faster than the speed of light up to 3c. However this is not an inertial velocity. Neither is this the galaxies proper velocity. Recessive velocity is a mathematical consequence of the separation distance. Lets use an example you measure galaxy A at 3c from Earth, and you were to teleport to a nearby galaxy to galaxy A its recessive velocity would be roughly the same as we would measure a nearby galaxy to the milky way, which is far less than 3c.

    So as recessive velocity is not an inertial velocity, galaxies will not gain mass due to inertia.

    a good article covering these misconceptions in a low level math article is
    "Inflation and the Cosmological Horizon"
    by Brian Powell
    http://tangentspace.info/docs/horizon.pdf
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Farthest stars and velocity
  1. Star formation (Replies: 2)

  2. Pulsar stars? (Replies: 4)

  3. Planck Stars (Replies: 6)

Loading...