Cosmic GDP drops 97% since peak star

Staunch Chicken Littles such as Alexander Ač love to talk about "peak oil", a hypothetical moment (and, in their opinion, a predictable and important moment) at which the global oil production reaches its global maximum.



But Phys.ORG has discussed an even more far-reaching peak of something, namely "peak star". The popular article is based on this paper:

A large H\(\alpha\) survey at \(z=2.23,\, 1.47,\, 0.84\, \&\, 0.40\): the \(11\,{\rm Gyr}\) evolution of star-forming galaxies from HiZELS (arXiv, published in Monthly Notices of the Royal Astronomical Society)

If we denote the number of produced stars per year as the "cosmic GDP", the years at which the cosmic GDP were maximized belongs to the distant memories. Since that time, the star production slowed down considerably. In fact, the "cosmic GDP" has decreased by a whopping 97% since that moment!




You would surely think that the Universe must be a horrible place to live if the "cosmic GDP" is just 3% of the value in those "good old times". Well, you would surely be wrong. Most of us didn't even know that the star production is so slow relatively to the maximum.

The peak was reached about 3 billion years after the Big Bang and I assure you, the world is a much better place today. During the "peak star", there wasn't even any Sun and the Earth – a planet that biased environmentalists consider more important than billions of other planets in the Universe ;-) – didn't exist, either.

I find it rather likely that 3 billion years after the Big Bang, our visible Universe contained no intelligent life but I am sure that many folks who think that "intelligent life is an inevitable omnipresent trash that immediately erupts almost everywhere" will disagree. We don't really know the answer.

It's also being estimated that despite the infinite length of the future life of our Universe that will increasingly approach the empty de Sitter space (its form of energy, the cosmological constant, already makes up over 70% of the energy density in the Universe, so we're already "pretty close" to the empty de Sitter Universe of the asymptotic future), the total number of stars in the cosmic history book will only increase by 5% since this moment. (Well, more precisely, we are talking about the total mass of the stars rather than the number.)

So if you measure the total "amount of fun in the life" as the integral of the product of the number of stars and (i.e. over) time, \(\int \dd t\,N_{\rm stars}\), then about 95% of the fun in the Universe has already taken place and almost nothing is awaiting us! We could also commit collective suicide and we could at most lose 5% of the fun events in our history.

The only problem with this pessimistic, nihilist conclusion is that we know very well that the "total amount of fun happening annually in the Universe" is proportional neither to the number of stars nor to their total mass. As I have mentioned, most of us believe that the life in the Universe is much more fun today than it was during the "peak star" 11 billion years ago.

The star production was needed for our Solar System to be born but many other events were needed for us to be here and to have some fun, too. The latter events depend on the existence of the stars and they're inevitably delayed by a certain period of time. And the things that decide about the GDP or the fun in life today – when the existence of the Solar System may be taken for granted – may proceed at a much faster rate so that those 7.5 billion years of the Sun's remaining life may be enough for a lot of fun – fun that is "almost" infinitely larger than what we have already seen (think about the speculations about the "technological singularity" which may be inaccurate but they're right about the point that the progress or GDP may continue to grow).

This objection is uncontroversial and kind of amusing in the case of "peak star". However, my point is clearly more far-reaching ideologically. My point is that the "amount of fun happening on the Earth every year" is clearly not proportional to the crude oil production, either. It isn't proportional to the electricity that is consumed, it isn't proportional to the number of SUVs or solar panels or soybeans that are sold, it is proportional to nothing particular that may be associated with the life in a given era.

The fun in the life is a totally independent quantity which depends on many things and the relationship of the fun in the life to other quantities is indirect, indeterministic, and it is constantly changing. Moreover, the relevant quantities today, such as the economists' GDP, are changing (and mostly increasing) by several percent per year while the 97% drop in 11 billion years corresponds to a modest 0.00000003% decrease per year which is negligible.

We have mentioned some of the reasons why "peak oil", much like "peak star" – even if we could determine or predict when it exactly occurs, which we can't – has no implications for the things we really care about in the world.

And that's the memo.