Posts Tagged ‘vlt’

THE COSMIC ROSETTA STONE

March 6, 2021

Archaeologists use tree-rings to date events several thousand years ago, climate scientists use ice-cores to decipher the state of the atmosphere as it was several hundred thousand years ago and astronomers bore holes in the Cosmos that potentially tell us of the Universe as it was billions of years in the past. But all these signals need some ingenious deciphering to get at the truth.

Look at the spectrum below, taken with the VLT, the world’s. most powerful optical telescope, sited high in the Chilean Andes. What is so remarkable about the spectrum, which stretches from the violet to the deep red, are all the dark lines imprinted upon it as the light from a very distant quasar has traversed Space on its immense journey to reach us. They probably have a fascinating tale to tell, far more momentous than the Rosetta Stone. But what is that tale? Why not have a go at cracking it?

This image, originally entitled “Fingerprints of the early Universe” can be dowloaded from The European Southern Observatory’s spectacular website eso.org under /images/ ‘Quasars and Black Holes’. It is an extremely deep spectrum of the Quasar (or ‘QSO’ standing for ‘Quasi-Stellar Object’) HE 0945-1050 (at redshift 3) taken with the UVES instrument on their Very Large Telescope (VLT) . What is remarkable about it is the presence of so many dark lines imposed on the spectrum, each the result of an absorbing cloud of gas lying along the line of sight to the quasar, which is several billion light years away from us. ( Acknowledge V. D’Odoricco, Osservatorio Astronomico di Trieste, Italy)

Experts have been staring at such QSO Absorption Line Systems (QSOALS for short, or ‘Spectral Ghosts’ as I prefer to call them) for over 50 years years now, and have come up with some intriguing clues. The lines, which have nothing to do with the quasar itself, are caused by atoms in distant clouds of gas lying at different redshifts ( or distances, because of the expansion of the Universe) along the line of sight. They know that from measuring the ratios of the wavelengths of those lines, ratios which in many cases are identical to to the ratios of spectral lines from ordinary atoms in the laboratory such as Hydrogen, Magnesium, Carbon, Oxygen, and so on. Since most of those atoms can only be made inside stars we infer that the mysterious clouds must also contain stars. But the only gas-clouds we know of containing stars are Galaxies, huge whirlpools of gas and stars , structures like the Andromeda Nebula and our own home The Milky Way ( See our post “Galaxy Gallery” for images). So what we must be seeing are the atoms in galaxies at different redshifts (distances away) intercepting and scattering out discreet wavelengths as the light-beam passes through them. Hence the spectrum is the log of an immense journey, and of all the encounters with galaxies which the light beam has made on its way from the Quasar to the Earth. Right? Well no.

Why not? Because there are about a hundred times too many black absorption lines to be accounted for by ordinary galaxies. A hundred times! That’s going to take some explaining. The experts of course have such an explanation: they say galaxies must simply be a hundred times bigger than we thought; they must have a vast invisible halo of gas around them which intercepts quasar light and etches all those lines we can see.

But don’t you think that explanation sounds just too glib, too ad hoc, rather too much like a child’s lie or the fairy tale about The Emperor’s New Clothes? I do. I think it’s a blatant attempt to brush a fascinating mystery under the carpet. Experts, especially those who make their living out of their expertise, don’t like to admit to mysteries, because they might undermine their claims to expertise. How often have you heard your doctor admit; “To be honest Mr. Jones I have no bloody idea what’s wrong with you.”

Of course the QSOALS experts claim to have at least some evidence in support of their Giant Halo Hypothesis. But if you look at that evidence very carefully, it’s not convincing at all; at least that’s what I think. I’ve got an alternative explanation for the dark lines, even more dramatic than Halos, but I won’t go into that here, because it too has its detractors.

Instead, the purpose of this post, is simply to point out that there is a great mystery out there and to encourage curious outsiders to have a go at solving it. After all The Rosetta Stone itself was solved by a young self-taught outsider, Jean-Francois Champollion who had taught himself Coptic Greek, which turned out to be the key … but that’s another fascinating story.

If it seems ridiculous to suggest that any but a professional astrophysicist (as I am myself) could make a serious contribution to this problem, that ignores how profoundly the Internet has changed Science. Here the germane facts are few. The relevant data is available for all to download from public archives, as are the existing scientific papers on the subject. And just remember that modern academics have become far too busy to really think any more. So you won’t have much serious competition from them.

So why not have a go? Deciphering the Cosmic Rosetta Stone will be far more exciting, and momentous, than cracking Egyptian history. But don’t expect it to come without effort. A couple of thousand hours of focussed reading should get one up to speed however. And here’s a useful tip to start: find out what the ‘ADS’ is ( it’s got something to do with NASA) and start using it.

Good luck. If nothing else you could have a hell of a lot of fun.