Cosmology 257least a denominator finite? I see that the infinity comes in because of the
growth of volume. The definition of inflation is this growth of the volume, and
any limit would make that infinite, but somehow one has to avoid that.
A. Linde Well, if we would know the answers, we would probably have written
about them a long time ago. But I would like just to give some analogies.
The first analogy is that there is a question “What is the time of the greatest
productivity of a person?” and another question is “What is the time when a
typical physicist produces his best work?” The typical time, or age, when the
best works are produced by physicists is between 20 and 30. Which would mean
that all of us must just retire now in shame because we all are out of maximal
productivity. On the other hand, when Ginzburg discussed this question at
our seminars (and he was already from my perspective at that time very old -which is my age right now), he said the following: this is a question of statistics.
If you are interested in what is the typical age physicists produce their best
works, you measure it weighting it with the total number of scientists (which
at that time was exponentially growing). That is why you have this youngness
paradox. But then, Ginzburg said, I am interested in my own productivity, andthat is a different measure. Now, you ask me which of these questions makes
sense and I tell you: both make sense from a statistical point of view. What
one should learn from this is not which of these measures is better but which of
them has any relation with the anthropic principle. That is one possible answer.Another possible answer is that actually we may take a very humble attitude,
and the humble attitude would be like that: all my life, I was wondering why Iwas born in Moscow; when I was a young pioneer, I was wondering why I am so
happy to be born in Moscow where the best children in the world Iive. When I
got older I still asked why I was born on Moscow, anyway. Then, right now, I
am saying: these questions may have no meaning because there are much more
Chinese. So, if I would just measure the total number of people, then by this
measure I would be an exception. But if I know that I am born in Moscow,
and I see everybody speaking English around, then I would think that this is
something surprising, this is something that I must explain.So, I must ask conditional probability questions: under given experimental
results, e.g. under the given result that I know what is Ap/p, do I still find the
present value of the cosmological constant surprising? No, I do not. But if you
let me consider all possible values of A and Ap/p and everything else, I will
have huge areas of landscapes with infinite volume and 1 will have nothing to
say. So, in a more humble way, that is exactly what experimentalists do: they
make new measurements and after these new measurements they evaluate whatis the probability of the next outcome of the next experiment. If you use the
anthropic principle in this way, there is a better chance that you will not say
anything nonsensical.