Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: neilep on 19/07/2008 22:05:09
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Dearest All,
Say I was a light year away from the nearest star and for a while I lost all power on my space ship. How would I be able to tell the passage of time ?....for the sake of the question there are no mechanical clocks on board !...and I'm not freezing to death either !
so, is there a way to calculate the passage of time in the middle of space ?
whajafink ?
neil
Troubled About Time
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The radiation from a pulsar could help you measure time passing, (unlikely but possible).
Pulsars are highly magnetized rotating neutron stars which emit a beam of light, but detectable by the telescopes mounted in Space. They emit electromagnetic radiation in the form of radio waves. Their observed periods range from 1.4 ms to 8.5 s.[1] The radiation can only be observed when the beam of emission is pointing towards the Earth. This is called the lighthouse effect and gives rise to the pulsed nature that gives pulsars their name. Because neutron stars are very dense objects, the rotation period and thus the interval between observed pulses are very regular. For some pulsars, the regularity of pulsation is as precise as an atomic clock.
You can hear pulsars here (http://www.jb.man.ac.uk/~pulsar/Education/Sounds/sounds.html)
[PSR B0531+21, The Crab Pulsar sounds like a pneumatic road drill, PSR J0437-4715 sounds like a weed-whacker]
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That's great RD and thanks for the link......I like hearing the sound clips !
One thing though....I imagine I'd have to have a star chart labeling where the pulsars are and the duration of each pulse ...else...without power to my ship....what would I use to measure the pulse interval ?
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If you had perfect pitch (http://en.wikipedia.org/wiki/Absolute_pitch) you could tell the frequency of a millisecond pulsar by ear, using a "cat's whisker (http://www.instructables.com/id/S32SCB5F6B7Q6YW/)" (no battery) radio receiver.
Alternatively if you had a clarinet on your space ship (!) you could compare the sound of the millisecond pulsar with the notes on the clarinet, using the beats phenomenon to tell when the frequencies were close.
PSR B1937+21 (http://www.jb.man.ac.uk/~pulsar/Education/Sounds/sounds.html) is 642Hz which is the second E above middle C.
If the pulses are several seconds apart you could count seconds in elephants: it takes about one second to say "one elephant", "one Mississippi" is also about a second.
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What's wrong with keeping an ordinary clock on your ship? It wouldn't stop working differently just because you're in Space. Except if it were a pendulum clock, of course. It would record the passage of local time perfectly well - no worse nor better than when on Earth.
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If you lost all power on your ship, you'd have more to worry about than telling the bloody time!
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If you had perfect pitch (http://en.wikipedia.org/wiki/Absolute_pitch) you could tell the frequency of a millisecond pulsar by ear, using a "cat's whisker (http://www.instructables.com/id/S32SCB5F6B7Q6YW/)" (no battery) radio receiver.
Alternatively if you had a clarinet on your space ship (!) you could compare the sound of the millisecond pulsar with the notes on the clarinet, using the beats phenomenon to tell when the frequencies were close.
PSR B1937+21 (http://www.jb.man.ac.uk/~pulsar/Education/Sounds/sounds.html) is 642Hz which is the second E above middle C.
If the pulses are several seconds apart you could count seconds in elephants: it takes about one second to say "one elephant", "one Mississippi" is also about a second.
Thank You RD,
Actually, I do have a clarinet in my attic !!
I better get it ready just in case I head back into space !
Thanks for the info on how to make a cat's whisker !
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What's wrong with keeping an ordinary clock on your ship? It wouldn't stop working differently just because you're in Space. Except if it were a pendulum clock, of course. It would record the passage of local time perfectly well - no worse nor better than when on Earth.
For the sake of the question I have omitted the use of a mechanical clocks because in time...they will fail .......and the premise of the post was really to invite investigation into how one could keep track of time without any ready made time pieces at all.
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If you lost all power on your ship, you'd have more to worry about than telling the bloody time!
For the sake of the question I am not freezing to death and can survive quite well without air and sustenance of any kind.......I'm Super Sheep !! [;D]
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OK....perhaps I should have not placed myself in space but in a locale where I can breathe, eat, drink and be well.........In a room with no windows !!
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A room with no windows might be difficult unless you coulc here the sound of the night birds or morning bird sounds..It seems your natural body clock would be a basic guide when you normally get hungry etc..Then again if you were still on the ship what about the stars.... oh but then the star chart would be helpful... what about the moonand sun.. depends on where you are there also eh?? what about drawing a sundial or making one... or are you too far away... in the room it would not help so perhaps temperatures could play a role to some degree.. otherwise body clock?
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OK....perhaps I should have not placed myself in space but in a locale where I can breathe, eat, drink and be well.........In a room with no windows !!
You could phone a friend to ask the time. Or arrange for them to text you every hour or so.
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Oooh good idea.. LOL!
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Not in answer to ewe're problem neilep, but going back to the traveling clock slowing down relative to the 'stationary' clock phenomenom: I've been wondering about synchronising both clocks using quantum entanglement events (the states would be unimportant - we're just using QE events to synchronise the ticks) - if the synchronising QE events could be done at rates approaching the Planck time period in the stationary clock timeframe, wouldn't they have to appear to be faster in the traveling clock timeframe? As the traveling clock approached 'c' the synchronising events would appear to be occurring in less than the Planck time. Hmm...
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A not very accurate way could be by measuring hair or nail growth.
Hair grows about 1/2" per month, not sure about nails.
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A not very accurate way could be by measuring hair or nail growth.
Hair grows about 1/2" per month, not sure about nails.
Neil is bald & bites his nails.
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A not very accurate way could be by measuring hair or nail growth.
Hair grows about 1/2" per month, not sure about nails.
Neil is bald & bites his nails.
[:o] [;D]
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Time is an relative thing. Looking at any time information from a remote source would be subject to relativistic effects so, if you wanted to boil an egg, you would be much better to use your local clock. Just imagine that you chose a very distant source, red-shifted by 50% - your egg would get 8 minutes!
We use standard frequencies like Hydrogen lines and Caesium atom vibrations, for our best clocks. Those would give you the most useful version of time on your ship. You would have to get hold of / invent a power source and just build one. (Assuming you had enough technology books to help you)
These, of course, only give you a frequency but can't be relied on to give you a 'correct' version of universal time unless they were running continuously from the time you left home. And, in any case, you would be out of step with that as soon as you started to move away.
Depending just how much gear you had on board, you could make yourself a clock based on a few other known quantities relating to what you had. You could find a Newton Meter in a drawer and some standard masses. This would let you calibrate a fairly good mechanical oscillator based on a 'mass on spring'. There are, alternatively, a number of chemical reactions with known rates under known conditions.
Perhaps it would be better to set the problem on a planet near a suitable Sun, where you have landed and had to start from scratch- food etc, not being a problem. ~This is what Humans did, in effect.
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If you had a very well equiped lab and engineering workshop you could build yourself an atomic clock. That's the point-
By deffinition
"The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom."
Provided you can find some Ceasium (and it's not that rare) you could reconstruct the second to a degree of accuracy where you need to take the effect of local gravity into account. How do you measure the gravity - well, you could use a pendulum clock. ;-)
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You could consider the fact that every atom in the universe is managing to keep its local time perfectly!