In Post#48 on July 9[SUP]th[/SUP], 2013 Sri Sangom raised this question:
“FYI, the following seems to be a puzzle to me:
"The
Big Bang theory is the prevailing cosmological model that describes the early development of the Universe, which is calculated to have begun
13.798 ± 0.037billion years ago."
"The farthest distance that it is theoretically possible for humans to see, called the
observable universe, is about 93 billion light years in diameter." (
Universe - Wikipedia, the free encyclopedia)
So, if we can observe up to 93 billion years, can we not see what happened before the Big Bang which is only 14 billion years old?”
Let me share my understanding:
There is a saying – “The universe is not only stranger than we imagine, it is stranger than we can imagine”
The concepts of space and time that we understand intuitively turns out to be inaccurate based on experimental observations.
Einstein’s work is now over 100 years old. An intriguing revelation is that nothing can travel faster than light. If I am traveling in a bus going at say 30 km/hour and I throw a ball in the direction of travel of bus at 5 km/hour, a person on the ground will see the ball being thrown at 30 plus 5 = 35 km/hour.
The fact that nothing can travel faster than light means that if instead of throwing a ball I throw a beam of light in the direction of the bus from inside the bus both the person in the bus and the observer in the ground will measure exactly the same speed of light. It is as if the speed of the bus has had no impact on the speed of light whatsoever.
The above understanding gives rise to the notion of time dilation. Let us say there are two people A and B of the same age and A decides to travel in space at a very high speed (fraction of speed of light). Such travel with such a high speed is not possible with today’s technology. However if it were possible and if A decides to return back to earth after 5 minutes of travel he will find that his friend B has aged by 70 years (and with great grand kids) in the 5 minutes experienced by A.
The above conclusions get verified every day in atomic reactors and other such devices.
The concept of space and time as we understand them are very strange indeed and we cannot use intuitive experience of our day to day world to apply when dealing with very small or very large systems.
I wanted to restate background in simpler terms before addressing the question.
The concept of space and time as we understand today is very strange and getting stranger with more observation. (A parenthetic statement I can make is that while the teachings of Upanishads have nothing to do with science, the concept of space and time alluded to there is finally getting caught up by modern science with improved experiments and better theories. This is a separate topic and I do not want to digress from the original question.)
The so called big bang gave rise to notion of space and time in this theory. So the concept of sense of time *before* time itself originated is meaningless. This is an answer to the question but gives rise to a different question
So if light originated in the current understanding some 14 billion years ago immediately after the big bang and since nothing can travel faster than light how is it that we can say that observable universe is at about 93 billion light years away?. In other words universe has existed for 14 billion years from our vantage point and any light that we see today did not originate before 14 billion years and the most distance we can actually say we see could be no more than 14 billion years.
For this we have to grasp that the notion of space itself. Space is expanding at a very rapid rate it turns out. By space we mean that akasha which has no particle (like air)
A question is space is expanding into what? Space is where objects expand into – but how can space itself expand? And supposedly it is expanding at a faster rate than speed of light itself. If it is expanding, what lies beyond space is a meaningless question just like it makes no sense to talk about time before big bang. The notion of space and time is very strange indeed and these are big topics of study for those that want to pursue fields like astrophysics.
It seems that nothing can go faster than the speed of light. It also seems that our universe is expanding faster than the speed of light today. Space itself that is expanding faster than the speed of light and in the process it is driving objects further apart. The idea that space is expanding faster than the speed of light is not in contradiction since the space has no mass! Only particle with any mass cannot go faster than speed of light. (Here again the notions of mass turns out to be not what they appear intuitively)
How did humans figure out that space is expanding? What observations led to this theory? Interested readers can find many books on this topic including those intended for laymen.
So light particle (or wave) that ‘left’ a newly created object is reaching us now after 14 billion years. In the meantime the object or galaxy has been moving away from us since space in which it is contained has expanded to be as far out as 93 billion light years. So we say that object that emitted that light some 14 billion years ago is actually away from us 93 billions light years because the intervening space has expanded!
Space is rapidly accelerating its expansion and there will be a time in the future when light that leaves an object in space can never reach us anymore and we will not be able to see any other galaxy. By that time earth and sun would have ceased to exist
ray2:
