Strong nuclear force, the weak nuclear force, and electromagnetic force behaved It occurred when there was a break in the fundamental forces of nature. The leading theory for the cause of the inflation says that The size of the fluctuations in the cosmic microwaveīackground indicate that the inflation could not have occurred before 10 -38 secondsĪfter the Big Bang. The Big Bang, but astronomers are not sure of the cause of inflation so they The inflation probably took place from about 10 -38 to 10 -36 seconds Universe experienced a time of ultra-fast expansion (called inflation). On theoretical grounds, astronomers think that the very early Regions even a degree apart in angular separation on our sky would haveĪt the time the microwave background was produced. Horizons? Running the expansion backward, astronomers find that The regions be so precisely the same if they are beyond each other's Microwave background looks the same to very high precision. Yet whenĪstronomers look in the opposite directions, they see that the
The regions in the opposite direction from which they came. Those photons haveĬertainly not had the time to travel across the entire universe to The age of the universe to reach us right now. The photons from the microwave background have been traveling nearly (recall the term event horizon in the discussion about black Horizons because the regions cannot be in contact with each other Not had enough time to travel between the regions, the regions are If two regions are far enough apart that light has The fastest speed that information can travel is Information to be exchanged between them so that they can equilibrate Temperature), is that they are close enough to each other for The only way for two regions to have the same conditions (e.g., Particularly the microwave background, look the same in all directions? The second problem with the standard Big Bang model is the It appears that the density/curvature was Percent off from perfect flatness within a few seconds after theīig Bang, the universe would have either re-collapsed before fusionĮver began or the universe would expanded so much that it would seem If the curvature of the universe was just a few Must have been to make the universe's current density be so near theĬritical density. Universe's curvature became fixed, the more finely tuned the density Move farther and farther away from the target. The permitted range ofĭeviation from the true direction gets narrower and narrower as you Slightly greater than the critical density a billion years after theīig Bang, the universe would have re-collapsed by now.Ĭonsider the analogy of the difficulty of shooting an arrow at a The time of the Big Bang because any deviation from perfect balance The balance would need to have been even finer nearer (very low density), the current nearly flat condition is definitely a
Very positively-curved (very high density) to very negatively-curved Negatively-curved open universe that astronomers have a hard timeįiguring out which model to choose. Is the universe so flat? Currently, the universe is so well-balancedīetween the positively-curved closed universe and the Theįirst is called the flatness problem-why is the universeĭensity so nearly at the critical density or put another way, why There are a couple of problems with the standard Big Bang model. Index in separate window This material (including images) is copyrighted!. Cosmology Embellishments on the Big Bang Chapter index in this window