We cannot go back in time and stick a thermometer in the early universe, but astronomers have done the next best thing, using an indirect technique to find out what the universe's temperature was 11 billion years ago. It was a chilly 9 K (-264 °C) back then, which is still warmer than today's prevailing temperature of less than 3 K (-270 °C).
Some of the coldest objects in the universe are gas clouds that fill the space between stars and galaxies. But even these are warmer than absolute zero, or 0 K. That is because they are heated by radiation leftover from the universe's earliest times.
Called the cosmic microwave background (CMB), this radiation was emitted by the hot plasma that filled the universe a mere 380,000 years after the big bang, which took place an estimated 13.7 billion years ago.
But as the universe expanded, the electromagnetic waves that comprise this radiation were stretched to longer wavelengths and lower energies, decreasing the radiation's temperature. Today, that temperature is just 2.7 K.
Now, a team led by Raghunathan Srianand of the Inter-University Centre for Astronomy and Astrophysics in Pune, India, has measured what the CMB temperature was 11 billion years ago, when the universe was just a fifth its current age.
They found it to be 9.15 K back then, with an uncertainty of 0.7 K in either direction. That is "in excellent agreement" with the 9.3 K temperature predicted in the big bang scenario, says team member Patrick Petitjean of the Institut d'Astrophysique in Paris, France.
The astronomers arrived at their figure by a very indirect route. What they actually measured was the temperature of carbon monoxide gas in a galaxy about 11 billion light years away.
The gas was detected by the way it intercepts light from an even more distant object called a quasar – a bright galaxy whose central black hole is consuming its surroundings.
The team used the Very Large Telescope (VLT) array in Paranal, Chile, to measure the wavelengths where the carbon monoxide absorbs the quasar's light. The wavelengths affected depend on the temperature of the galaxy's gas, whose heat is thought to come from the CMB.
Charles Bennett, chief scientist for NASA's Wilkinson Microwave Anisotropy Probe (WMAP) mission, which measures the CMB, says it is important to make such measurements to test scientists' expectations. "It's nice to see consistent things in different ways," he told New Scientist.
Journal reference: Astronomy & Astrophysics (vol 482, p L39)
Cosmology – Keep up with the latest ideas in our special report.
By Edmund N. Willoughbies
Thu May 15 19:30:59 BST 2008
Here is a question for you presumed relativists: how big is the universe? Can you take a humongous ruler to it and give us an intelligible measurement? No. The reason is simple: that ruler is a part of the universe; it would have to be beyond the universe as such in order to give a comparable answer to the question of its dimensions, which is an anti-relativistic gesture. Moving on from my initiated digression, though not far from it, why do you plod lock, step, and key along the assumption that this can be done in terms of temperature? These are very serious theoretical issues. It is time we cleaned up our concepts before plunging full force into the throng of inadmissible human contrivances as if they have a genuine correlation with the the world, in churlish support of a seemingly well-supported theory. A theoretical skepticism, not just a practical one, is that by which science must also be guided.By Chris Ramage
Thu May 15 23:23:50 BST 2008
Yes that is nice and all BUT how does this blabber relate to the above topic??By Anon
Fri May 16 21:29:33 BST 2008
Pardon my upcoming rudeness... Are you genuinely stupid or just senseless? The man, Edmund, makes a clear point here.By Paul
Fri May 16 03:31:46 BST 2008
I thought the universe had cooled because of its expansion. But it doesn't have any edges and therefore no volume.By Fred Sagen
Fri May 16 09:06:30 BST 2008
A sphere has no two-dimensional boundary but has surface area.By Aza
Sat May 17 06:51:03 BST 2008
If you understand that all electromagnetic radiation takes time to reach us, then you should understand that all the EMR from quite large distances away from us, will inevitiably be from periods of the early universe.By William Smith
Sun May 18 15:50:14 BST 2008
I don't really see what the size of the universe has to do with the temperature of an interstellar gas cloud. What is different about measuring the temperature of gas in our atmosphere and measuring the temperature of interstellar gas clouds 11 billion light years away, except that the measurement from the gas clouds is done indirectly using the differing absorption characteristics of carbon monoxide in the gas clouds at different temperatures?By Polemos
Thu May 15 20:26:18 BST 2008
"Today, that temperature is just 2.7 K."By Don Jennings
Thu May 15 20:39:30 BST 2008
How are you going to justify all that in 2015? I predict you will have a modicum of egg on your face.By Small Minority
Fri May 16 09:09:05 BST 2008
While I usually disagree with the dribble from Polemos, he/she is pretty much on the money about 2014/15 though. Although the events described are not close to what will really happen.By Whipster
Fri May 16 10:39:14 BST 2008
I'm sorry about this... I'm not having a dig.. But how does this relate to the article? Even at all?By Mr Michael Mouse
Thu May 15 23:33:36 BST 2008
2014 you say?By Sett
Fri May 16 06:07:58 BST 2008
Right. Liquid LSD was not invented for use in bubble baths.By Pelotard
Fri May 16 08:18:10 BST 2008
Say...By Polemos
Fri May 16 09:17:14 BST 2008
1) The slowing of atoms by use of cooling apparatuses produces a singular quantum state known as a Bose condensate or Bose–Einstein condensate. (http://en.wikipedia.org/wiki/Bose-Einstein_condensate )By Small Minority
Sat May 17 04:07:01 BST 2008
The reference to 666 is really quite simple. If you read in Daniel how king Nebuccadnezer made an image whose dimensions were 60x6. While it is not mentioned that the depth was 6, historically if the depth is not given then it is the same proportion as the width, so you end up with 60x6x6. This image was built in defiance of the interpretation given to king Neb by God through Daniel. The original image was shown with gold as the head, for the chest, bronze for the thighs, iron for the legs and iron mixed with clay for the ...By Polemos
Fri May 16 09:34:17 BST 2008
(long URL - click here)By Whipster
Fri May 16 10:50:09 BST 2008
Absolute poppyCOCK... Polemos - your obviously quite a smart guy, so why not devote it to something serious, quantifiable.. Or better yet... Why not place your posts where they belong - on http://www.new-un-realistic-speculator.com?
By Polemos
Fri May 16 11:19:18 BST 2008
Conversion of quantity into quality:By R. Peters
Fri May 16 02:04:45 BST 2008
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