I mean hot.
Scientists have just discovered that the extreme drought bedeviling America's midsection is being caused by a gigantic halo of hot gas surrounding the Milky Way. Okay, okay... We're kidding about the cause of the drought – but not about that gas cloud, which is a few hundreds of thousands of light years in diameter, weighs …
I mean hot.
Maybe all galaxies are wrapped in this hot fluffy stuff, and so this accounts for all the dark matter. As usual, we shall have to wait for the boffin-esque pronouncements.
Quick answer: no
Longer answer: This is the missing baryon content ( 'ordinary matter' contents of the universe). The dark matter is far more than double the mass of stars ;something like 5-10 times the baryon content -so more like 10-20 times the mass in stars that we see. People have been looking for this missing baryon content in hot gas for some time. That is why several groups have seen it.
A quick Google on "missing baryons" will tell you about it.
Does this mean that humanity will likely never escape the confines of this galaxy (since the whole thing is surrounded by a burning cloud millions of degrees hot?).
Heat is not temperature. So we're good to go.
It says diffuse cloud, so I'd assume that you wouldn't hit to many of them on your way out; a bit like solar radiation or cosmic rays. It's a bit like the difference between being underwater compared to out in the rain and being scaref of drowning. Yes it's another issue to overcome because you don't want to get wet,but probably trifling compared to the problem of actually getting there (maybe like worying about the temperature in the Sahara deset when you go out for a walk - starting in Sydney)
Well, its not as if we can already easily manage to leave our own solar system. Last probe that succeeded was launched in 1977 and only around 2007 did it finally leave the solar system (although it did visit some outer planets first).
Somehow I don't think we're ever going to find this galaxy "confined".
Not as long as we're still living in the three dimensions.
Probably not - this "cloud" is probably a lot less dense than a respectable vacuum that can be produced in a laboratory.
Still, going through it at relativistic speeds might be a problem, because of the gas itself, not specifically its temperature.
> Not as long as we're still living in the three dimensions.
And once we're living in a fourth dimension we can neatly side step the cloud anyway.
Mine's the one with the sleeves sewn together around a Klein bottle.
I always considered time the fourth dimension
"so I'd assume that you wouldn't hit to many of them on your way out"
You'd probably hit an awful lot of them if you were travelling at the kind of speed required to be viable for inter-galactic travel.
What a well written and well articulated piece of entertaining journalism. Kudos, I signed up just to be able to post this.
Your're new here aren't you?
Glad you like it. Take some time to thumb through the back-issues, for instance the LHC coverage.
what effect does this discovery have upon omega? Are we still heading for the Big Rip in 50-odd billion years' time or are we now facing down the Big Crunch?
Last I remember he was trapped in the anti matter universe
"Last I remember he was trapped in the anti matter universe"
Didn't he die trying to invade Amsterdam?
Thanks for this. A refreshing change from some bloke being reported to have had some problem with some Apple thing (and I'm not in the Apple camp).
OMG its the Galactic Barrier !
Dang it, can't believe somebody beat me to it!
Similar clouds have been known to surround galactic clusters, but not around our own. That is of course hard to do, and has been likened to "drawing up a map of the city whilst standing in the market square." A more accurate analogy would be "drawing up a map of the city whilst standing on a playground somewhere in the (unfashionable western) suburbs"
Thumbs up to the scientists for attempting perhaps not the impossible, but at least the very, very improbable!
Degrees Kelvin? Degrees Kelvin?
You are my old physics teacher and I claim my £5.
Sad that Rik hasn't bothered to correct this egregious error ! One of the aspects I most appreciate about Richard Chirgwin's Reg postings on scientific matters - he actually seems to read the comments and to be willing to correct errors that are pointed out. Kudos !...
Drop him an email, they don't always have time, it was only posted.... at quarter to one this morning (from the pub?) he's probably got higher priorities than reading the comments.
While we're nitpicking, "comprised of" as in "[...] such as protons and neutrons that are comprised of three quarks" is an error that someone claiming to be a professional writer really shouldn't make. "Composed of" would be correct here. "Comprised" means "made up of", the appending of an additional "of" is redundant.
"such as protons and neutrons that are comprised three quarks"
Yes that sounds right. (Sarcasm, your suggestion is idiotic).
Perhaps "such as protons and neutrons, comprising three quarks".
At first I read the headline as Half of Milky Way's Mass Found in Milton-Keynes Gas Cloud, and thought it was a bit of juicy gossip about an old boss of mine.
That's a complicated way of saying "huge". I bet you had to check the spelling.
Now I'd like to know which blighter lost it in the first place?
All this talk of measuring background radiation, "the heat of the big bang", as a variance of 1 or 2 degrees from absolute zero - how on earth (or not) did they miss this bloody great inferno surrounding us?
My very slightly informed guess for why this extremely hot gas cloud was much more difficult to detect than the cold cosmic background radiation is that the black body radiation at extremely high temperatures is skewed toward the far blue end of the spectrum (so the use of X-ray detection satellites). In addition to the difficulty detecting X-rays (even using a satellite), the high energy per photon for X-rays reduces the number of photons emitted for a given energy. This cloud is also extremely diffuse, so the X-ray glow viewed from a telescope's relatively narrow cone would be relatively faint (I suspect).
How do they estimate temperature? Do they not estimate particle velocities by measuring doppler shift and then calculate temperature from the kinetic energy of the ions via the Bollzmann constant?
This assumes that the gas is in equilibrium, more or less like an ideal gas. Apparently it's convenient to do this so that other thermodynamic concepts can be applied.
At such high temperatures gas would indeed glow, even when quite dilute. It's actually more likely to be fast moving streams and sheets of cool partly ionised gas.
That cloud looks to have rounded edges, we are not allowed to talk about it anymore until we get a license from Mapple.
Please remove this article from your site El Reg or I will have to take you to trial.
Ok I lied, I could never sue you guys. :)
Always the last place you look.
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