Pow! Zap! (Big) Bang?! (Introduction)

by Balance_Maintained , U.S.A., Saturday, September 25, 2010, 19:51 (5152 days ago) @ David Turell
edited by unknown, Saturday, September 25, 2010, 19:59

The specific form of Hubble's expansion law is important: the speed of recession is proportional to distance. The expanding raisin bread model at left illustrates why this is important. If every portion of the bread expands by the same amount in a given interval of time, then the raisins would recede from each other with exactly a Hubble type expansion law. In a given time interval, a nearby raisin would move relatively little, but a distant raisin would move relatively farther - and the same behavior would be seen from any raisin in the loaf. In other words, the Hubble law is just what one would expect for a homogeneous expanding universe, as predicted by the Big Bang theory. Moreover no raisin, or galaxy, occupies a special place in this universe - unless you get too close to the edge of the loaf where the analogy breaks down.
>
>The current WMAP results show the Hubble Constant to be 73.5 +/-3.2 (km/sec)/Mpc. If the WMAP data is combined with other cosmological data, the best estimate is 70.8 +/- 1.6 (km/sec)/Mpc.-WMAP-
By definition, according to the laws of motion, starting from a single point, and every point moving by the amount for the same amount of time, would give you a sphere. Not a loaf of raisin bread. -d=Vit+1/2at^2 where d is displacement, Vi is initial velocity, t is time, and a is acceleration. -If the universe is not homogeneous, the whole BBT breaks down.