Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: justaskin on 01/01/2009 07:15:12
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Hi All
My first question in the forum is.
If there are things/objects in our universe that are traveling
faster than light do we have any instruments that would
detect such things/objects.If so what are they?.
I have thought for a long time that the speed of light at about
300,000 km/sec was not all that fast in the scheme of things.
I have googled the question I ask but have never seen such a question
asked.If someone has a link to such a question with answer I would like
to see the answer.
Look forward to getting some answers to some of my msings
Cheers
justaskin
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This has nothing to do with the topic, but is your user name 'just a skin' or 'just ask in'?
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This has nothing to do with the topic, but is your user name 'just a skin' or 'just ask in'?
The last one just ask in
Cheers
justaskin
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To detect a particle it needs to interact with it the particles that we know, strong and electromagnetic interactions are quite easy to detect. Weak interactions are much more difficult and we cannot currently detect individual particles that interact only gravitationally (dark matter) we can only detect their presence on a galactic scale although there are currently quite serious efforts to detect variations in dark matter density on a solar system scale. We know of no other interactions. So to detect a hypothetical faster than light particle it must interact using one of the interactions that we can detect.
Father than light particles have been proposed in some theories they are called tachyons (look this up in Google) but are not currently in favour and have never been detected.
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Surely tachyons are more than just out of favour. The theories that predicted them have been shown to be flawed. If any theory predicts tachyons, there must be a flaw in it somewhere.
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To detect a particle it needs to interact with it the particles that we know, strong and electromagnetic interactions are quite easy to detect. Weak interactions are much more difficult and we cannot currently detect individual particles that interact only gravitationally (dark matter) we can only detect their presence on a galactic scale although there are currently quite serious efforts to detect variations in dark matter density on a solar system scale. We know of no other interactions. So to detect a hypothetical faster than light particle it must interact using one of the interactions that we can detect.
Father than light particles have been proposed in some theories they are called tachyons (look this up in Google) but are not currently in favour and have never been detected.
Thank you for the explanation.
So it is as I have thought for a while.It is not that things can't move faster than light but that with our current state of technology we just have nothing to detect them if they do.
About moving information faster than light.
If I had a tube stretching from earth to the sun and it is filled end to end with metal balls and I push one more ball in the earth end would one ball drop out the sun end at the same time.If so would that not be moving information faster than light?.
Cheers
justaskin
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I think you would have to be very very very strong to be able to push that metal ball through [:0]. But say that it was a wire which stretched from the Earth to the Sun and at the end of it was a light bulb and you passed a currents through the wire, would the light bulb light up immediately [???]. Wouldn't that be moving information faster than the speed of light.
What do you think?
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No, the force from you pushing the ball through the tube could only transfer along the tube at the speed of sound. The current through the wire would not be the speed of light, If memory serves its about 1/3 the speed of light.
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Please forgive my ignorance of physics [:I] but why does the force pushing the ball through the tube only transfer the balls along the tube at the speed of sound... [?] unless I misunderstood something
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I think you would have to be very very very strong to be able to push that metal ball through
Ok how about a metre long bar when I push on one end does the other end move at the same time?.
Some other examples
A train.When the engine starts does the end carrage start at the same time?.
The little ornaments you see in offices and homes of half a dozen balls suspended from a frame.
When you lift the ball at one end and let it go and it strikes the ball next to it and the ball on
the other end is propelled forward is the energy transfer immediate or is there a finite period for the
energy transfer to take place?.
Cheers
justaskin
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I'm still trying to figure out Madidus_Scientia statement [???] [:P] [:P]
Going by what MS said, obviously there is a finite period for the energy transfer to take place...
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I remember learning that it would be near-impossible to detect tachyon. We might be able to make a negative imaginary matter particle from the decay of tritium, but chances of detecting this particle that would oscillate throughout the imaginary time dimension is generally considered impossible.
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Yes, even with only a metre long rod the fastest a force from one end can act on the other end is the speed of sound in the material. To simplify think of a long stick made of just one row of atoms. These atoms are all vibrating bouncing off each other at a certain speed depending on their temperature. So if i hit one end, that atom has to travel to the next atom before it can pass on this force. Then that atom has to hit the next, and so on. The atom I first hit does not directly influence the one on the opposite end, the energy must travel through the intervening atoms.
This can be very fast in a solid because the atoms are closely bound together. In a gas such as air its much slower, the reason the speed of sound in normal air is what it is is because that's how fast the atoms in the air are travelling and bouncing into each other, therefore that's the fastest a sound wave can possibly propagate through the medium.
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If I had a tube stretching from earth to the sun and it is filled end to end with metal balls and I push one more ball in the earth end would one ball drop out the sun end at the same time.
So no matter how much force you applied whether it be 10000 N or 500000000 N they will all move along at the speed of sound?
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Correct
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Yes, even with only a metre long rod the fastest a force from one end can act on the other end is the speed of sound in the material. To simplify think of a long stick made of just one row of atoms. These atoms are all vibrating bouncing off each other at a certain speed depending on their temperature. So if i hit one end, that atom has to travel to the next atom before it can pass on this force. Then that atom has to hit the next, and so on. The atom I first hit does not directly influence the one on the opposite end, the energy must travel through the intervening atoms.
This can be very fast in a solid because the atoms are closely bound together. In a gas such as air its much slower, the reason the speed of sound in normal air is what it is is because that's how fast the atoms in the air are travelling and bouncing into each other, therefore that's the fastest a sound wave can possibly propagate through the medium.
Ok has a physical experiment been done to check this or is this been deduced by theory.
Would you have a link to such experiment?.Thanks
Cheers
justaskin
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justaskin This is a very common misconception about materials. you have to remember that materials that you think as being very hard and rigid do distort under forces think of a pane of glass, this seems very hard and rigid but does bend a bit if you press it. Glass fibres can be very flexible where the length of the fibre is many thousands of times its width scaled up. So consider a glass rod an inch thick this would feels like very rigid if it was a foot long but if it was a thousand miles long you could tie it in knots (on that scale of course any foot length section would still be pretty straight). Now think about you tube of balls. The balls do distort and the tiny amount of compression would mean that the force would only be transmitted a relatively short distance of a few miles at most. Also the rate at which the distortion can be transmitted as an impulse even if the balls were freely moving without friction is the velocity of sound in the material which is around one thousandth of the velocity of light in most rigid solid materials like glass.
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Thanks Soul Surfer
It sure does take some getting your head around the fact that if you push
on one end of a metal bar that there is a finite time before the other end
moves.
Cheers
justaskin
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Or you could see it as spacetime creating a unified forcefield (Startrek:)
A kind of (from us looking out on it) four dimensional bubble in which 'everything' (all forces) are restricted by each others interaction.
Inside that bubble there is no 'room' for anything traveling FTL, if you by that mean faster than light in a vacuum?
As I see it.
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If I had a tube stretching from earth to the sun and it is filled end to end with metal balls and I push one more ball in the earth end would one ball drop out the sun end at the same time.
So no matter how much force you applied whether it be 10000 N or 500000000 N they will all move along at the speed of sound?
Well to be more clear if you kept applying the very large force your balls might continue to accelerate to very great speeds out of the tube, but when you start pushing one end, the quickest the other end can realise it is moving as well is determined by the speed of sound in that material.