## Tuesday, August 11, 2015 ... /////

### Catastrophe worse than global warming: the Universe is dying

How a childish formulation penetrates to almost all media

If you open Google News Science right now, you won't have any doubt what is the most important event in science today: the Universe is dying! (The #2 story is probably worse: the tadpoles everywhere on Earth are dying, too.)

It's official. Astronomers confirm it. A galaxy survey confirms. The universe is dying or slowly dying and so on. Virtually identical titles may be found in the USA Today, CBS News, The Week Magazine, Forbes, RedOrbit, the International Business Times, and 200 other news outlets.

I am convinced that most of the people who have studied the Universe for decades must have reacted to the titles just like I did, namely by the question: What do they really mean? What is hiding behind this meaningless proposition?

A minority of the media avoided the "death of the Universe" theme and were more informative. The Telegraph wrote that it's the stars that die out. And the BBC and a few others chose a different verb: the Universe is fading – or fading away.

The actual observation that is hiding behind these anthropomorphic propositions is a rather mundane one. A team of astronomers mostly in Western Australia has decided that the total amount of energy that is being emitted by one galaxy is about 1/2 of what it was 2 billion years ago. This factor of two seems to hold for numerous wavelengths.

Because the stars' energy output went down in this way, the future seems terrible. We're told about some good news: the last stars – oldest, lowest mass stars – will keep on shining for some 100 billion years. So we may still enjoy some quality time.

It is not hard to see that virtually all the "science journalists" have copied the assertions about the "death of the Universe" and almost all the details from this press release at ICRAR.ORG.

If an organization like that invents a catchy slogan and issues a press release, it is virtually guaranteed that it will be copied in the global media and fed to a billion or billions of readers. And the substance that Simon Driver, an astronomer, was smoking right before he invented the "Universe is dying" slogan is therefore hugely affecting how a significant fraction of the mankind will look at the Universe today.

I think that science journalism shouldn't work like that. It shouldn't be this incredibly mindless exercise of copying of rather stupid assertions by not so intelligent yet fame-seeking speakers.

The Universe is not dying. At least if you agree that a random small healthy kid isn't dying, you must also agree that the Universe is not dying. The word "dying" is reserved for some last moments of someone's life and the age of the Universe is clearly much lower than what it will be when it will "die". Moreover, the true "death of the Universe" shouldn't depend on stars – and the Universe will exist indefinitely, or perhaps for the Poincaré recurrence time of $\exp(10^{120})$ years (or any other reasonable units).

Our Cosmos isn't dying. It's just aging, like everything else. When things are aging, they're changing. Almost everything in the Universe (many qualitative properties and every quantitative one) is changing, at one speed or another. Many of the changes are irreversible ones – thanks to the second law of thermodynamics and perhaps a few similar time-reversal-asymmetric laws. The Universe is expanding and cooling and getting more technologically advanced (because of our progress) and undergoing many other changes. But the word "death" should be used for some special, terminal moments, and that's not the moments the Universe is going through these days.

By its essence, the survey wasn't really new. They looked at 200,000 galaxies at 21 wavelengths. Previous similar surveys have used a smaller number of wavelengths.

But what I also find disappointing is the poor precision of the statements about the energy emitted by a "corner of the Universe" – and the missing explanations how they have actually decided that this statement was right.

The problem is that they say that the "energy emitted by this corner of the Universe" has halved but they don't seem to care that this "corner of the Universe", much like the whole Universe, is expanding. The expansion is in no way negligible. In these billions of years, we have been or we are gradually entering the era in which the cosmological constant decides about the majority of the expansion of the Universe.

And the pure cosmological constant (of the observed magnitude) would imply – and indeed, will asymptotically imply – that all the linear dimensions in the Universe will be doubled each 11 billion years or so. The Universe is going to grow basically exponentially. 2 billion is 1/5.5 of the doubling time. But because of the cubic law, the doubling time for the volume of the Universe is 11 billion years over three, so 2 billion years from the survey is 3/5.5 of the volume doubling time – more than one-half of the volume doubling time. This makes a difference.

So the question really is: Is their "factor of two" decrease describing some intrinsic fading of each galaxy by this factor, or is one-half of this fading explained by the conventional dilution of the Universe that is inseparable from the cosmic expansion? The press release doesn't say anything about this question.

Now, good cosmologists and astronomers obviously know the answer to this question. But the broader point is that they know the answers to all similarly basic questions. The new survey hasn't changed an iota about the scientific knowledge of these issues. It improved on a technicality that is neither catchy nor fundamentally important – the number of wavelengths in the survey – and added a childish slogan about the "death of the Universe".

It's incredibly unfortunate that this low-brow combo – completely unimaginative, superficial improvements of things done 20 years ago combined with some cheap slogans produced for the stupidest readers – is what seems to be the optimally balanced package that guarantees that a press release will spread to hundreds of global news outlets.

No doubt, many scientific projects are bound to be just "small improvements" of their predecessors that lead to no paradigm shift (and are more or less guaranteed from the beginning not to lead one from). It may make sense to fund some of them, anyway. But couldn't the people tame their marketing obsession, their desire to sell the minimum results for the maximum amount of music? And couldn't the journalists ignore some researchers' frantic efforts to make themselves more visible than they should be?