How do cosmologists estimate how long ago the big bang happened?
- 8 years agoFavorite Answer
Quite simply, the truth:
Information needed to calculate the exact age of the universe may not exist today.
The Hubble red shift is interpreted as the universe being 13.5 billion light years in radius.
This could be true if their assumptions about the red shift are correct.
If this is the case then it took 13.5 billion years to reach it's farthest limits and it should take a minimum of 13.5 billion years to return,for 27 billion years.
The universe is a quantum entity so it must have a maximum and a minimum size.
I believe the universe is a maximum of 6 billion light years in radius.
Since it expands at the speed of light it must be about 12 billion years old.
The universe could be much older than 12 billion years but it's radius is no bigger than 6 billion light years.
When the universe reaches it's maximum size it's outer perimeter may go out of existence but the space-time pulse that launched it could go on for much longer.
When the pulse does stop the remainder will expand for 6 billion years then go out of existence.
There is no information existing that will tell us how long it has been in existence.
Incidentally;if a galaxy is the end stage in the evolution of the universe and it is in a state of accelerated collapse viewing it from any side would be interpreted as accelerating away from the viewer.
Additional reading on 'how' exactly:
The Universe is 13.75 billion years old, primordial helium has been spotted for the first time and key evidence for the inflationary period immediately after the Big Bang has been found. But not all the new discoveries by NASA's Wilkinson Microwave Anisotropy Probe (WMAP) appear to fit cosmological theory.
Previously, scientists using data from WMAP measured the time since the Big Bang to be an incredibly precise 13.73 billion years (give or take 0.12 billion years). And now, using the same space-based observatory, the age of the universe has been refined even further, adding another 20 million years to the total (plus or minus 0.11 billion years).*
Using data from the first 7 years of operation, this refined universal age could be arrived at. Previously, the first 5 years of WMAP observations were used; the longer the observatory is operational, the longer the exposure time, therefore the results become more precise.
This news comes as a series of papers from the WMAP team have been published concerning several different aspects of the observations.
WMAP is constantly surveying the furthermost reaches of the universe, measuring the very faint "echo" of the Big Bang. This echo is known as cosmic microwave background (CMB) radiation, a remnant of the vast energies unleashed as the universe burst into being.
By mapping the slight variations of temperature in this background radiation, a lot of information about the conditions of the early universe can be gleaned, but cosmologists aren't only interested how long ago the Big Bang occurred. They are trying to find further evidence for what we believe happened in the moments after the Big Bang and now WMAP is filling in the gaps of our knowledge.
In addition to the precise age measurement, WMAP has been able to detect small acoustic oscillations (the cosmic equivalent to sound waves) in the CMB radiation, and the signature detected suggests primordial helium was generated in predicted quantities in the early stages of universal evolution.
Also, by measuring the fluctuations of the CMB radiation over all scales, there is evidence that suggests there was a very rapid expansion just after the Big Bang. This supports inflation theory and provides further evidence for the mysterious "Dark Energy" that is predicted to permeate through the universe, causing space-time to expand at an accelerated rate.
Although this all sounds great, there's one observation that can't be explained by theory. The amount of CMB radiation spotted near clusters of galaxies is greater than expected. According to theory, CMB photons should interact with these clusters, getting kicked to higher energies. WMAP cannot detect these higher energy photons, so there should be a deficit of CMB photons around clusters. This is not the case and scientists will probably be confused by this for some time to come.
WMAP continues to open our eyes to the nature of our universe by measuring the Big Bang echo, supporting current theories about how the cosmos started out, but challenges other theories as to how CMB radiation should behave. Although the WMAP mission is set to end in the fall of 2010, its results will reverberate for years to come.
*The uncertainties in the measurements don't come from astronomers lack of accuracy, far from it. When measuring cosmic times and distances, very slight errors may creep into the calculations.
- 4 years ago
Most of the time the same approach I do, through watching at Wikipedia (but prior to that, it most commonly would had been the historical past books): Now it can be style of complex to put a timeline on it, but it surely looks like the idea was once created sometime round 1931 with the aid of Georges Lemaître, who hypothesized that if you happen to run Hubble's increasing universe in reverse that it started from a very small universe. Nonetheless, the speculation wasn't commonly approved unless 1964 it seems that: "the discovery and confirmation of the cosmic microwave historical past radiation in 1964 secured the large Bang as the high-quality conception of the foundation and evolution of the cosmos." So the significant Bang theory would have taken situation at any place from 50 to 80 years ago.