1. Sophrosyne

    B The Hubble deep field photos and the edge of the universe

    The Hubble telescope was able to capture images of the edges of our visible universe in its deep space photos. These were among its most breathtaking pictures. They show galaxies from about 14 billion light years away, as well as in the past, from the very beginning of time and space in our...
  2. M

    A Interpreting hubble data

    this graph: from: can be found on many sites. the origin is D=0 and t=0. cosmology claims the universe is accelerating over time. the graph shows acceleration over...
  3. Joe Fatuch

    I How does the speed of light affect expansion acceleration?

    I may have a fundamental misunderstanding of the concept, but I was wondering, how does the accelerating expansion of the universe calculate for the time dilation in light travel? From my understanding, we know that the universe expansion is accelerating because the farthest galaxies that we...
  4. K

    I Problem Hubble parameter

    This is the time derivative to calculate the speed which a galaxy moves away from another galaxy. I don't understand how they get from da/dt (xi − x1) to (∙a)/a a(t). (xi − x1). Could anyone explain this? vi(t) = d/dt (ri(t) − r1(t)) = d/dt a(t)(xi − x1) = da/dt (xi − x1)...
  5. fencewalker

    I Help w/ Hubble

    EEE degree w/ phys minor. hubble's graph shows velocity increasing over distance, not time. an image 10 mil ly away is 10 mil y old (t = -d/c) the origin of hubble's graph is d=0 and t=now, not 0 older images are faster and older image means younger galaxy distance is proportional to age, which...
  6. G

    I Accelerated expansion and Hubble plot

    Hello! I have a question regarding the effect of the accelerated expansion of the universe on the Hubble plot (redshift over luminosity (or distance). I understand that for relatively nearby galaxies, this appears to be a linear relationship but that because of the accelerated expansion of the...
  7. Stephanus

    B Integral in Hubble Flow

    Dear PF Forum, While learning why the net energy of the universe is zero. I've been reading about the expansion of the universe, and of course in it, Hubble Flow.'s_law = 73km/s per Mega parsec = 3.26 light year. In the...
  8. L

    I Universe is a sphere that is centered on any observer? How?

    I read here, , that, "What we call the "observable universe" (or the "Hubble Volume") is the spherical region, about 90 billion light-years in diameter, that is centered on any given observer. This is the only part of the...
  9. Matt atkinson

    Question about errors, Hubble's constant

    Homework Statement I am just looking through some old notes I have from for cosmology, and there's something cropped up that i can't seem to figure out: Say I have two (or more) values for H_o each with errors such as: H_{o_1}=70^{+a+b}_{-c-d} and H_{o_2}=69^{+e+f}_{-g-h} How would I go...
  10. T

    Hubble lookback time based on energy density.

    Homework Statement If the energy density of the vacuum were the value 10^133 eV/m^3 , what would the value of the Hubble lookback time be for such a universe with no curvature and no other matter? Homework Equations Possible equation... ...Lookback time = ln(1+z)/H The Attempt at a Solution...
  11. quantumfunction

    How many Hubble Spheres are in the universe?

    From what I understand, our Hubble's sphere is just relative to earth and has a diameter of 93 billion light years putting the edge of the observable universe at 46-47 billion light years away. So every object in space will essentially have it's own Hubble's sphere and objects near the edge of...
  12. T

    Hubble's Law and Hubble's Constant

    Hi there! I'm having some trouble understanding Hubble's Law and Constant and would be grateful for some help. So Hubble's Law shows that the most distant galaxies have the greatest red-shift, as they are moving away from us fastest. This shows that all galaxies are moving away from each other...
  13. G

    Expanding Universe

    How one can say that the space is expanding by just verifying that the galaxies are speeding away from each other?
  14. 2

    What exactly is the Hubble parameter?

    I'm looking at general relativity and particularly considering what happens at the Big Bang. I think the Friedman equation is H^2=\frac{8\pi G}{3}\rho so I see that as the matter density goes to infinity, H goes to infinity. According to this video (around 10:10), this is where the problem lies...