I went out today for a longish solo bimble around my favourite lanes (oh all right then, pubs). I noticed that during the day I passed from Warwickshire into Worcestershire and vica versa several times. Now, it occurred to me, at one off these crossings that as Borsetshire is mythically located between Warks and Worcs, I had also crossed that county several times - and at a speed somewhat in excess of the speed of light.
Listen out for the sonic booms over Ambridge in tomorrow's Archers. That'll be me. :-)
Er, actually, it wouldn't be a sonic boom would it? What's the light equivalent? Photic boom?
Er, actually, it wouldn't be a sonic boom would it? What's the light equivalent? Photic boom?
There is an equivalent to a sonic boom. When a particle goes faster than the speed of light in a certain medium, Cherenkov radiation is emitted.
No, that's not a nonsense statement. The speed of light in a vacuum is an absolute limit. In matter, such as water or glass or air, light travels more slowly. This slowing down factor is the index of refraction. Now, if a particle is emitted by (say) a radioactive source or a collision at a particle accelerator and enters the medium going faster than the speed of light in that medium, light is given off as a sort of shock wave. That is the source of the blue glow which film makers love when showing shots of nuclear reactor cooling ponds.
Cherenkov radiation is also used as an important detection technique in particle physics. The angle of the cherenkov cone gives information on the velocity.
John Mallard wrote: > > Er, actually, it wouldn't be a sonic boom would it? > What's the light equivalent? Photic boom?
Cherenkov Radiation
That's given off when light "slows down" isn't it, from a "faster" medium to a "slower" one?
Not meaning to be rude, but not quite. when light enters a medium which is "slower" - ie. there is a higher index of refraction, it bends. That's how lenses work. The bend is given by Snells' Law.
Lynda or Robert???
-- Rob
Please keep conversations in the newsgroup so that all may contribute and benefit.
"John Hearns" <[email hidden]> wrote in message "]news:[email hidden]...
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Simon Mason said:
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John Mallard wrote: > > Er, actually, it wouldn't be a sonic boom would it? > What's the light equivalent? Photic boom?
Cherenkov Radiation
That's given off when light "slows down" isn't it, from a "faster"
medium
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to a "slower" one?
Not meaning to be rude, but not quite. when light enters a medium which is "slower" - ie. there is a higher index of refraction, it bends. That's how lenses work. The bend is given by Snells' Law. Also, the bend is the exact right size to minimise the total time taken to go from start to end through both medium. This is known as the "Principle of Least Time". I Trust you are all enjoying this morning's physics tutorial?
Indeed I am. So when I am measuring the Refractive Index of a chemical in our lab at BP, like I have done for the past 30 years, I can now finally understand what I've been doing all this time. Thanks ;-)
Now if you can explain in layman's terms how our Inductively Coupled Plasma Emission Spectrophotometer works, when I measure the Iridium content of a substance I'll be a happy man ;-) -- Simon M.
Now if you can explain in layman's terms how our Inductively Coupled Plasma Emission Spectrophotometer works, when I measure the Iridium content of a substance I'll be a happy man ;-)
Now if you can explain in layman's terms how our Inductively Coupled Plasma Emission Spectrophotometer works, when I measure the Iridium content of a substance I'll be a happy man ;-)
"John Hearns" <[email hidden]> wrote in message "]news:[email hidden]...
Quoted message said:
Simon Mason said:
Now if you can explain in layman's terms how our Inductively Coupled
Plasma
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Emission Spectrophotometer works, when I measure the Iridium content of
a
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substance I'll be a happy man ;-)
You've got me there! Dang nebbit, honest to betsy, pesky spectrophotometers...
LOL. BTW, I would have *loved* to have been a particle physicist. It must be fantastic to peer into the inner workings of the Universe by unravelling weirder and more and more numerous sub atomic particles, then having to come up with some theory (and the "proof"😉 of how they all fit together. So you are doing my dream job, but I wasn't any good at maths, so I would have been no use at it :-)
On Mon, 24 May 2004 14:04:18 +0100, Simon Mason wrote:
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LOL. BTW, I would have *loved* to have been a particle physicist. It must be fantastic to peer into the inner workings of the Universe by unravelling weirder and more and more numerous sub atomic particles, then having to come up with some theory (and the "proof"😉 of how they all fit together.
Well, many nights spent staring at computer screens down deep holes in the French countryside. So you
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are doing my dream job, but I wasn't any good at maths, so I would have been no use at it :-)
Truth be told, I make my living these days configuring and installing Linux clusters (Beowulfs).
Most dream jobs probably turn out to be not as fantastic when actually living that dream...
I started off in theoretical physics, planning to understand All about the 11 Hidden Dimensions. Passing through computational physics, atmnospheric sciences and internet/new media programming I'm now researching ICT for older people...
On Mon, 24 May 2004 10:34:18 +0100, John Hearns <[email hidden]> wrote (more or less): ...
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Going wildly off-topic, Cherenkov radiation is used as the basis for several many very interesting detectors. I'm a particle physicist. Bet you regret asking the question now :-)
In deep, clear water neutrino observatories suspend strings of photomultipliers in spherical pressure housings. nikhef.nlintroe.htmOpen ↗ Sounds fun. Plenty of sunshine out in the Med off Corsica.
And still others only get to go to Yorkshire, into the deepest darkest parts of a coal mine htere. (Mind you, I only know that detector is for neutrinos. Maybe it isn't a Cherenkov radiation detector, but some other kind of neutrino meter.)
"Roos Eisma" <[email hidden]> wrote in message "]news:[email hidden]...
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Most dream jobs probably turn out to be not as fantastic when actually living that dream...
I started off in theoretical physics, planning to understand All about the 11 Hidden Dimensions. Passing through computational physics, atmnospheric sciences and internet/new media programming I'm now researching ICT for older people...
Well I hope there are still a few of you trying to sort it all out ;-) You're right about the job though, I find more pleasure in cycling to and from work than the actual job and it's a very good job, all things considered.
"Trevor Barton" <[email hidden]> wrote in message "]news:[email hidden]...
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The way it works is that you put the sample in, probably after preparing it in some manner, and then pres a few buttons in some predetermined order, and then wait a while while the machine whirs and pops, and then something either appears on the screen or from a printer giving you the answer.
"Trevor Barton" <[email hidden]> wrote in message "]news:[email hidden]...
Quoted message said:
The way it works is that you put the sample in, probably after preparing it in some manner, and then pres a few buttons in some predetermined order, and then wait a while while the machine whirs and pops, and then something either appears on the screen or from a printer giving you the answer.
