New Scientist Space reports: 'OUR universe appears to be unfathomably uniform. Look across space from one edge of the visible universe to the other, and you'll see that the microwave background radiation [CMBR] filling the cosmos is at the same temperature everywhere. That may not seem surprising until you consider that the two edges are nearly 28 billion light years apart and our universe is only 14 billion years old.
'Nothing can travel faster than the speed of light, so there is no way heat radiation could have travelled between the two horizons to even out the hot and cold spots created in the big bang and leave the thermal equilibrium we see now.
'This "horizon problem" is a big headache for cosmologists ...'
Imagine 20 students in a room seated in a circle. A tough hour-long essay exam was given. To the professor's surprise, everybody wrote exactly the same thing. The conclusion is inevitable: info was shared by all to all.
Problem is, it takes at least 30 minutes to discuss the thing to the one seated beside. The professor can only wonder thus at the homogeneity of the answers. That is, given that one can talk to only two persons at most during the one hour.
To recap: (a) the 30-minute factor is the speed of light; (b) the classroom is the observable universe; (c) the maximum of two nearby students whose answers one can know would be the 'horizon'.
Related post: Greene & Barrow on cosmology's 'horizon problem' [Part 2]
Related post: Inflation as horizon problem's solution [Part 3]
Related post: On inflation, horizon problem, and CMBR
[Image created by Cosmology Curiosity.]
Technorati Tags: Alan Guth, big bang, cosmic inflation, cosmology, horizon problem, Inflation, inflationary universe
Who says the microwave background radiation ends at the edges of the known universe or resulted from the Big Bang? Maybe the MBR is a constant medium in which the big band 28Byr universe expanded / is expanding!
Posted by: Tom Mercury | July 09, 2006 at 11:06 PM
Can't the problem be solved if the "edges" that are opposite each other are on a curve...not a straight line?
Posted by: Crai | May 14, 2008 at 05:57 PM
I don't understand why anyone would assume that the MBR would NOT be uniform. If the Big Bang was an expansion from a singular point, wouldn't the laws of physics... and even quantum physics... dictate uniformity.
Alternately, we must understand that we are looking out from OUR central point through a Fog of background radiation, there may be micro-variation (in cosmological terms) that we cannot yet measure with our primitive technology.
Posted by: Robin Ader | May 16, 2008 at 08:03 AM
Big bang! ...Just a leak in the membrane.
Posted by: J. L. Lee | June 02, 2008 at 07:30 AM
I think the clarification needed is MBR is not from the cingularity of the big bang, but from later when it cooled enough to allow photons to travel outward. That is a standard temperature and would account for the uniform appearance.
Posted by: larry furtsch | July 17, 2008 at 05:43 PM
My first thought is the relevance or rather non-relevence of size when size is a factor however we are in an area of not knowing the limits outwardly from our cosmological horizon thus it's a pattern on a tablecloth. A constant by content?
Posted by: Dwight Frost | August 03, 2009 at 12:31 PM
It seems to me that if the universe is cyclic, the radiation has had plenty of time to mix over many cycles, even if most of is reabsorbed while the universe contracts.
Posted by: Richard Dowd | November 28, 2009 at 02:54 PM