It is believed by many that there is something called 'absolute reality',
and that it is a different matter whether or not we humans can know all of it. Certainly
there are limits to what we can know. But even within the knowable domain, reality
today may not be the same as reality in the future. I shall come to this time aspect
later in this post. But even at a particular instant of time, there is no such
thing as absolute reality. As argued convincingly by Hawking & Mlodinow(2010), all that we
have is MODEL-DEPENDENT REALITY; any wider or deeper notion of reality is a baseless
myth.
Does something
or somebody exist when we are not viewing it? There are two opposite models for
answering this question. Which model of reality is correct? Naturally the one that
is simpler, self-consistent, and most successful in terms
of its predicted consequences. This is where materialism wins hands down. The
materialistic model is that the
entity exists even when nobody is observing it. This model is far more
successful in explaining reality than the opposite model. And we can do no
better than build models of whatever there is to observe, understand and
explain.
Suppose 100
persons are asked to describe an object, including its colour, and all of them
say that it is a chair. Further, suppose 98 of them say that it is a red
chair, but the other two disagree about the colour seen by the majority. If further
investigation shows that these two persons have a colour-blindness problem, the
model of reality we humans build is that the object is a red chair.
But suppose it
turns out that these two persons are not colour blind, and no matter
what tests we carry out, we are unable to explain why they do not see or
describe the chair as red. We then go (tentatively) by the majority view, or consensus.
Of course, any model of reality can change in the light of new data and
insights. This is the approach we adopt in science for building up our
knowledge. We build models and theories of reality, and we accept those which
are most successful in explaining what we humans observe collectively.
A model is a
good model if: It is elegant and self-consistent; it contains no or only a few
arbitrary or adjustable parameters; it explains most or all of the existing
observations; and it makes detailed and falsifiable (i.e. testable) predictions.
That brings me
to the M-theory (cf. Part 14) and the
cosmic-inflation model (Part 17) in
cosmology. Are they good models of reality? There are eminent scientists who
vehemently attack both of them, and have even proposed alternative models. Nothing
unusual about that. At the cutting edge of science, the edge is blunt or
nebulous, rather than sharp: Experts disagree on many issues, and fight it out.
But out of this informed debate consensus emerges gradually, usually when
additional ('issue clincher') data become available, or when some genius
formulates a great new model. M-theory and the multiverse idea are the most
accepted we humans have at present, even though there are many
arbitrary-looking parameters, and loose ends. In due course the models would
get either established or rejected, but they are the best (i.e., most accepted,
even beautiful) models of reality at present.
The
cosmic-inflation model of reality ties up so many loose ends in cosmology, and
explains so many observations, that some form of it is highly likely to survive
in any scientific version of cosmology.
Reality is
nothing deeper than the best available scientific model for it. Often a phenomenon or entity is so complex that no sensible model has been formulated yet. In such a case, we have to wait till science makes more progress.
I now come to
the time dependence of reality. Let us consider
our current understanding of the origin of our universe. Scientists agree, by
and large, that our universe began with a Big Bang 13.72 billion years ago. This
model stands on three pillars: (i) the observed 'Hubble expansion' of the
universe; (ii) the observed cosmic-wave background; and (iii) the fantastic
agreement between the predicted and observed relative abundances of the light
elements hydrogen, helium, and lithium. Lawrence Krauss has discussed them in
detail in his recent (2012) book A Universe from Nothing. I shall consider only the first of them here.
Observations show that the rate of expansion of our universe is increasing (cf. Part 15). What is more, the observable universe is expanding at present at a rate that is not much lower than the speed of light. Galaxies which we can see today will one day recede from us at a speed greater than the speed with which even the fastest possible signals (electromagnetic radiation) from them can reach us. They will then become invisible to us, permanently. This will happen ~2 trillion years from now.
We and our solar system will die out in ~5 billion years. But other
civilizations and advanced science can emerge elsewhere in the distant future. Suppose
you are one of those astronomers in the very distant future. When you look
around the cosmos with your highly advanced telescopes, you would see none
of the ~400 billion galaxies we humans see today. What will be your model of
reality then? Certainly not the same as ours at present. There is no such thing
as absolute, unique, invariant reality.
We are 'lucky' to be living in a period when evidence for the Big Bang is
available. Astronomers far enough into the future will have no evidence
and no reason to believe that the Big Bang occurred at all, and that
there were galaxies other than their own.
We live at a very special time . . . the only time when we can observationally verify that we live at a very special time! (Lawrence Krauss et al.)
You can see a timeline of the far future in the Wikipedia.
I agree with your arguments but I dont understand why people with scientific background move to shits [ http://www.huffingtonpost.com/peter-russell/brain-consciousness_b_873595.html].
ReplyDeleteThe truth prevails, ultimately. Satyamev jayate.
DeleteObviously, mere "scientific background" is not sufficient for scientific temper..
DeleteVery true.
DeleteDear Prof. Wadhawan,
ReplyDeleteThank you very much for the nice write up. While, I certainly disagree with the M-theory concept and the concept of "Multiverse", which to me sound more like a product of "belief", a scientific belief. Peter Woit, wrote a book "Not Even Wrong" has been the most vocal critic of the M and String theory. Just because something is mathematically correct, it does not mean it exists in nature, for example, the "White Hole". White holes are perfect mathematical models but have we found one yet? The "Black Hole", is also within the realms of doubt. That is the problem with today's scientific establishment, where the just hang on a theory and then try to push the observation into a pre-established theory or come up with theoretical assumptions that have no basis, no proof. Have we seen the "Multiverse" yet, through any means of observation?
Thank you.
Thanks for your comment, Rudra. As we all know very well, only the truth prevails ultimately. The best theory will win. The question is: What is the best theory we have at present? You are welcome to tell us about the best theory.
ReplyDelete