Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Jim Roche on 19/07/2008 10:36:28
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Jim Roche asked the Naked Scientists:
Hi Doctor Chris,
It's a lonely job being a bored teenage spaceman on watch some 183,000 miles above Earth's surface. There's simply nothing to do man!
To keep me attentive I have to keep hold of a super fine, and super strong thread, on the end of which is a 10 pound lump of stone which I have to keep just above ground level. Then it occurred to me; if I let go of the thread the stone would instantly fall to Earth, and as I am further above the Earth's surface that light travels in a second, am I not "doing something that is faster than the speed of light?"
Answers please if you can be bothered, because I'm off to see if I can get them to put a Yo-Yo on the end of this thing, or something a bit more interesting than a brick
Yours faithfully
Space Man Lethy Thargix Indo-lent
AKA Jim Roche - Leeds
What do you think?
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The simple answer is "no". [:D]
I suppose, if you're that bored up there, I could explain the reason so that you've got something to read.
It's to do with transfer of information. In this instance the information is that you have let go of the string. That information needs to travel along the length of the string, passing from molecule to molecule. I'm not sure of the speed at which such information would travel along the string, but it certainly wouldn't exceed the speed of light, and would probably fall well short of it.
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After you let go of the thread it would be ages for the bottom end to go slack. Letting go would set up a pulse / wave which would travel down the thread at, not the speed of light, but the speed of sound in the thread.
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Sophie - I wondered whether it would be the speed of sound. Thank you for clarifying that point.
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As a firm believer in empirical study I conducted this experiment with my 2 year old son whilst he held a torch.
The premise was to get James to turn the torch on at the same time I dropped the payload towards the Earth.
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Here I am happily orbiting the Earth at 186,001 miles !
Notice that it's quite a nice day out !
...and now the empirical bit........
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At this instant I instructed James to turn the torch on....and I also let go of the payload...VOILA.....my payload did in fact reach the Earth before the light from my torch (hmmm..must remember to put batteries in next time and also explain to James what a torch is)
Glad I could help.
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I note that dropping the payload caused your spaceship to rotate. That could be a bit dangerous, don't you think?
It also appears that you have obliterated most of arctic Norway. Those poor reindeer! [:-'(]
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Hmmm...ah !!...well...The Earth span...not my spaceship !
......and as far as Norway is concerned....I'm sure Slartibartfast (http://en.wikipedia.org/wiki/Slartibartfast) can just make another one ! [;)]
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Hmmm...ah !!...well...The Earth span...not my spaceship !
So explain the angle of your hand in the 2nd photo.
......and as far as Norway is concerned....I'm sure Slartibartfast (http://en.wikipedia.org/wiki/Slartibartfast) can just make another one ! [;)]
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fbestsmileys.com%2Fthumbs%2F7.gif&hash=2abc85c2dea35d2f56283b5a399ac052)
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Hmmm...ah !!...well...The Earth span...not my spaceship !
So explain the angle of your hand in the 2nd photo.
That's gravity lensing for ya !! [;D]
......and as far as Norway is concerned....I'm sure Slartibartfast (http://en.wikipedia.org/wiki/Slartibartfast) can just make another one ! [;)]
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fbestsmileys.com%2Fthumbs%2F7.gif&hash=2abc85c2dea35d2f56283b5a399ac052)
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Hmmm...ah !!...well...The Earth span...not my spaceship !
So explain the angle of your hand in the 2nd photo.
That's gravity lensing for ya !! [;D]
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fbestsmileys.com%2Fdoh%2F2.gif&hash=fef6931e562a6dc5fd0fd29a97202c70)