Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Alan McDougall on 23/05/2016 14:59:22
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We know that a particle that has mass albeit tiny like a proton used in the Large Hadron Collider, is subject to the light speed barrier!
In the collider they send particles, from opposite ends to collide in the middle.
What baffles me about this, is that they accelerate each opposing particle to 99.999% c, so time flow should alter relative to the outside world, as well as between each colliding particles (protons), in that both must become much more massive, and that time should slow down/run slower relative to each other
Another example if you stand stationary to a person walking or running toward you, for that person who is in in motion, time is running slower and by the time he reaches stationary you. He would have become, infinitesimally younger than you!
A proton is a physical object just very tiny, but it must obey the laws of physics, just like a much larger object like the planet Jupiter. Due to Jupiter greater gravity field, than the Earths, if we put two extremely accurate clocks and synchronize them exactly, the clock on Jupiter on will run immediately begin to run slower than the than the one on Earth.
The question then begs, how do the protons ever meet at the center of the collider, to smash up into hadons for examination by the physicists.?
Alan
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Well, they definitely do experience very significant time dilation, but this does not prevent them from colliding. It just means that they can't collide with a relative velocity of c or greater (which one would expect from a classical treatment of two particles heading towards each other, each with a speed of 99.999% c wrt the detector...)
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Well, they definitely do experience very significant time dilation, but this does not prevent them from colliding. It just means that they can't collide with a relative velocity of c or greater (which one would expect from a classical treatment of two particles heading towards each other, each with a speed of 99.999% c wrt the detector...)
For clarity in the rest frame of either proton the other proton will not appear to be moving greater than c towards it. In the laboratory frame the closing speed (the speed at which the scientists observe the two proton approaching each other) will be slightly less than twice c. This is acceptable because the closing speed of two moving objects is not an actual speed and proper use of the Lorentz transforms from the laboratory frame to the rest frame of either proton will give you the correct answer of a relative velocity less than c between the two particles.
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For clarity in the rest frame of either proton the other proton will not appear to be moving greater than c towards it. In the laboratory frame the closing speed (the speed at which the scientists observe the two proton approaching each other) will be slightly less than twice c. This is acceptable because the closing speed of two moving objects is not an actual speed and proper use of the Lorentz transforms from the laboratory frame to the rest frame of either proton will give you the correct answer of a relative velocity less than c between the two particles.
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I cant see how the scientist would observe the two opposing proton approaching each other "at almost twice c," when c is a universal constant unaffected from any view point, it always equal c or less never more, which is an impossibility?
Although the protons are accelerated to 99.999% of c from each and opposite ends of the collider, they do not meet at 186% approx. c, but paradoxically at less than c, difficult to understand but a fundamental reality of the universe.
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I cant see how the scientist would observe the two opposing proton approaching each other "at almost twice c," when c is a universal constant unaffected from any view point, it always equal c or less never more, which is an impossibility?
The key is in the fact that the speed at which you see two separate objects moving toward (or away from) each other is not the speed of an actual object. It is the speed at which the distance between them shrinks (or grows) not the speed of any actual object. The scientists measures both protons as moving slightly less than c with respect to himself (or herself) but in opposite directions. As such the speed at which the protons approach each other is slightly less than twice c.
https://en.wikipedia.org/wiki/Faster-than-light#Closing_speeds <- A concise explination
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I cant see how the scientist would observe the two opposing proton approaching each other "at almost twice c," when c is a universal constant unaffected from any view point, it always equal c or less never more, which is an impossibility?
The key is in the fact that the speed at which you see two separate objects moving toward (or away from) each other is not the speed of an actual object. It is the speed at which the distance between them shrinks (or grows) not the speed of any actual object. The scientists measures both protons as moving slightly less than c with respect to himself (or herself) but in opposite directions. As such the speed at which the protons approach each other is slightly less than twice c.
https://en.wikipedia.org/wiki/Faster-than-light#Closing_speeds <- A concise "explination" (Spelling error?)
That is a wikipedia artical and not always the best source of facts like we are discussing! I disagree with it anyway, because, Einsteins theory now fact, states that
nothing can exceed the speed of light. That speed, explained Einstein, is a fundamental constant of nature: "It appears the same to all observers anywhere in space".
The same theory/ now fact, says that objects gain mass as they speed up, and that speeding up requires energy. The more mass, the more energy is required. By the time an object reached the speed of light, Einstein calculated, its mass would be infinite, and so would the amount of energy required to increase its speed. To go beyond the infinite is impossible.
It is all about diminishing returns, you have to put in more and more energy to get closer and closer to the speed of light, until all the energy in the universe could not get it you up to c
It requires an infinite amount of energy, to accelerate an object of mass up to c an obvious impossibility. Hypothetically if this, impossibility were to happen it would destroy the universe.
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That is a wikipedia artical and not always the best source of facts like we are discussing! I disagree with it anyway, because, Einsteins theory now fact, states that
nothing can exceed the speed of light. That speed, explained Einstein, is a fundamental constant of nature: "It appears the same to all observers anywhere in space".
Too bad if you don't agree with what it says because it is correct. Generally speaking just because a source sometimes is wrong doesn't mean it is always wrong. You need to provide a better reason than just that wikipedia is occasionally wrong.
http://www.numericana.com/answer/relativity.htm#add <- Someone else writing about closing speeds
On the straight addition of closing speeds.
Two spaceships head toward each other at 70% and 80% of the speed of light, respectively. They are 3 light-years apart. When will they meet?
Well, the distance between them is seen to decrease at a rate equal to 0.7 + 0.8 = 1.5 times the speed of light. They'll meet in exactly 2 years.
Relative Speed vs. Closing Speed
The previously discussed relative speed of two moving objects is defined as the speed of one object seen by an observer at rest with respect to the other.
This is entirely different from what's sometimes called the closing speed, which is the rate of change of the distance between two moving objects (as seen by an observer who is linked to neither).
When motion along a straight line is considered at time t by an independent observer, an object moving at velocity -u is at abscissa -u t and an object moving at velocity v is at abscissa v t. The signed distance separating the latter from the former is clearly (u+v)t and the rate of change of that quantity (the signed closing speed, if you will) is u+v. In prerelativistic mechanics, there is no difference between the relative speed and the closing speed of two objects (because two moving observers are supposedly experiencing the same flow of time). In relativistic mechanics, this ain't so.
Confusing the two notions can be a great source of puzzlement when the relevant conditions are not properly analyzed. In particular, the following Fizeau effect is correctly explained by the relativistic expression for relative velocities, whereas the Sagnac effect is due to the difference in the closing speeds of two light beams that either chase a moving mirror or race toward it (those closing speeds are c-v and c+v, respectively).
The same theory/ now fact, says that objects gain mass as they speed up, and that speeding up requires energy. The more mass, the more energy is required. By the time an object reached the speed of light, Einstein calculated, its mass would be infinite, and so would the amount of energy required to increase its speed. To go beyond the infinite is impossible.
It is all about diminishing returns, you have to put in more and more energy to get closer and closer to the speed of light, until all the energy in the universe could not get it you up to c
It requires an infinite amount of energy, to accelerate an object of mass up to c an obvious impossibility. Hypothetically if this, impossibility were to happen it would destroy the universe.
I reiterate that either proton will only ever see the other proton as moving at less than the speed of light. The people in the lab will also see both particles as moving less than the speed of light. However, the people in the lab will see that the distance between the particles is shrinking at faster than the speed of light. This is perfectly fine because the separation between two objects is not a physical thing and as such cannot be accelerated and strictly speaking does not have a speed. This is an artifact of the lab frame of reference not a property of the particles. However, it is a good idea to keep it in mind because it is a subtle thing and many people say very silly things because they don't understand the difference.
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Einsteins theory now fact, states that nothing can exceed the speed of light.
Wikipedia and agyejy did not disagree with Einstein.
A scientist standing beside a particle accelerator sees one proton coming from the left at slightly less than c. She sees another coming from the right at slightly less than c. Nothing exceeds the speed of light.
It's more complex to imagine, but if they were sitting on one of these protons, they would see the other proton coming towards you at slightly less than c.
both must become much more massive
Let's put some numbers on this.
- A proton has a rest mass of 0.937GeV/c2
- In the LHC (once it reaches full design power), a proton will have an energy of 7000GeV (or 7TeV); the rest-mass contributes very little to this.
- So the energy of the proton has increased by a factor of 7500
- This requires the proton to travel at 99.9999991% of c (ie about 3m/s less than c)
- When two such protons collide, the energy of the collision is 14000GeV (or 14 TeV).
- When you apply the relativistic addition of velocities formula (see below), the velocity of an oncoming proton (from the viewpoint of the other proton) is 2mm/day less than c!
- Note: When you do this last calculation, it requires more digits than your average calculator or spreadsheet!
See: https://en.wikipedia.org/wiki/Velocity-addition_formula#Special_relativity
and that time should slow down/run slower relative to each other
Time slows by exactly the same ratio as the mass increases and the length reduces.
This is the Lorentz factor: https://en.wikipedia.org/wiki/Lorentz_factor
It requires an infinite amount of energy, to accelerate an object of mass up to c an obvious impossibility.
CERN does require a large amount of energy, about 200MW in the European summer months (off-peak period for nuclear power plants). But it's not infinite.
Nor is the energy of the colliding particles infinite - it is "only" 14TeV.
It's the addition of velocities formula that means they can achieve their results with only one third the power consumption of the nearby city of Geneva.
See: http://www.lhc-closer.es/taking_a_closer_look_at_lhc/0.energy_consumption
Einsteins theory now fact
This is verging on philosophy, but no serious physicist would say that any theory is a proven fact.
At best they would say things like:
- Einstein's Special Relativity gives extremely accurate results
- Einsteins' Special Relativity is a very good approximation to the real world; General Relativity is an even better approximation
- Einstein's General Relativity has passed numerous tests of increasing sensitivity over the past century with flying colors (including the recent measurement of Frame Dragging and detection of Gravitational Waves).
- But it has known deficiencies, like it is not compatible with quantum theory near a black hole
- And various serious physicists are continuing to work on alternatives and improvements (eg some form of quantum gravity)
Oops - overlap with agyejy
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Einsteins theory now fact, states that nothing can exceed the speed of light.
Wikipedia and agyejy did not disagree with Einstein.
A scientist standing beside a particle accelerator sees one proton coming from the left at slightly less than c. She sees another coming from the right at slightly less than c. Nothing exceeds the speed of light.
It's more complex to imagine, but if they were sitting on one of these protons, they would see the other proton coming towards you at slightly less than c.
both must become much more massive
Let's put some numbers on this.
- A proton has a rest mass of 0.937GeV/c2
- In the LHC (once it reaches full design power), a proton will have an energy of 7000GeV (or 7TeV); the rest-mass contributes very little to this.
- So the energy of the proton has increased by a factor of 7500
- This requires the proton to travel at 99.9999991% of c (ie about 3m/s less than c)
- When two such protons collide, the energy of the collision is 14000GeV (or 14 TeV).
- When you apply the relativistic addition of velocities formula (see below), the velocity of an oncoming proton (from the viewpoint of the other proton) is 2mm/day less than c!
- Note: When you do this last calculation, it requires more digits than your average calculator or spreadsheet!
See: https://en.wikipedia.org/wiki/Velocity-addition_formula#Special_relativity
and that time should slow down/run slower relative to each other
Time slows by exactly the same ratio as the mass increases and the length reduces.
This is the Lorentz factor: https://en.wikipedia.org/wiki/Lorentz_factor
It requires an infinite amount of energy, to accelerate an object of mass up to c an obvious impossibility.
CERN does require a large amount of energy, about 200MW in the European summer months (off-peak period for nuclear power plants). But it's not infinite.
Nor is the energy of the colliding particles infinite - it is "only" 14TeV.
It's the addition of velocities formula that means they can achieve their results with only one third the power consumption of the nearby city of Geneva.
See: http://www.lhc-closer.es/taking_a_closer_look_at_lhc/0.energy_consumption
Einsteins theory now fact
This is verging on philosophy, but no serious physicist would say that any theory is a proven fact.
At best they would say things like:
- Einstein's Special Relativity gives extremely accurate results
- Einsteins' Special Relativity is a very good approximation to the real world; General Relativity is an even better approximation
- Einstein's General Relativity has passed numerous tests of increasing sensitivity over the past century with flying colors (including the recent measurement of Frame Dragging and detection of Gravitational Waves).
- But it has known deficiencies, like it is not compatible with quantum theory near a black hole
- And various serious physicists are continuing to work on alternatives and improvements (eg some form of quantum gravity)
Oops - overlap with agyejy
If i read you right you are agreeing with me and not the wikapedia article?
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That is a wikipedia artical and not always the best source of facts like we are discussing! I disagree with it anyway, because, Einsteins theory now fact, states that
nothing can exceed the speed of light. That speed, explained Einstein, is a fundamental constant of nature: "It appears the same to all observers anywhere in space".
Too bad if you don't agree with what it says because it is correct. Generally speaking just because a source sometimes is wrong doesn't mean it is always wrong. You need to provide a better reason than just that wikipedia is occasionally wrong.
http://www.numericana.com/answer/relativity.htm#add <- Someone else writing about closing speeds
On the straight addition of closing speeds.
Two spaceships head toward each other at 70% and 80% of the speed of light, respectively. They are 3 light-years apart. When will they meet?
Well, the distance between them is seen to decrease at a rate equal to 0.7 + 0.8 = 1.5 times the speed of light. They'll meet in exactly 2 years.
Relative Speed vs. Closing Speed
The previously discussed relative speed of two moving objects is defined as the speed of one object seen by an observer at rest with respect to the other.
This is entirely different from what's sometimes called the closing speed, which is the rate of change of the distance between two moving objects (as seen by an observer who is linked to neither).
When motion along a straight line is considered at time t by an independent observer, an object moving at velocity -u is at abscissa -u t and an object moving at velocity v is at abscissa v t. The signed distance separating the latter from the former is clearly (u+v)t and the rate of change of that quantity (the signed closing speed, if you will) is u+v. In prerelativistic mechanics, there is no difference between the relative speed and the closing speed of two objects (because two moving observers are supposedly experiencing the same flow of time). In relativistic mechanics, this ain't so.
Confusing the two notions can be a great source of puzzlement when the relevant conditions are not properly analyzed. In particular, the following Fizeau effect is correctly explained by the relativistic expression for relative velocities, whereas the Sagnac effect is due to the difference in the closing speeds of two light beams that either chase a moving mirror or race toward it (those closing speeds are c-v and c+v, respectively).
The same theory/ now fact, says that objects gain mass as they speed up, and that speeding up requires energy. The more mass, the more energy is required. By the time an object reached the speed of light, Einstein calculated, its mass would be infinite, and so would the amount of energy required to increase its speed. To go beyond the infinite is impossible.
It is all about diminishing returns, you have to put in more and more energy to get closer and closer to the speed of light, until all the energy in the universe could not get it you up to c
It requires an infinite amount of energy, to accelerate an object of mass up to c an obvious impossibility. Hypothetically if this, impossibility were to happen it would destroy the universe.
I reiterate that either proton will only ever see the other proton as moving at less than the speed of light. The people in the lab will also see both particles as moving less than the speed of light. However, the people in the lab will see that the distance between the particles is shrinking at faster than the speed of light. "This is perfectly fine because the separation between two objects is not a physical thing" and as such cannot be accelerated and strictly speaking does not have a speed. This is an artifact of the lab frame of reference not a property of the particles. However, it is a good idea to keep it in mind because it is a subtle thing and many people say very silly things because they don't understand the difference.
You are again wrong the separation between the two protons "Is a Physical Thing" it is space-time and nothing can move through or approach each other at greater than c Period my friend!
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Well, they definitely do experience very significant time dilation, but this does not prevent them from colliding. It just means that they can't collide with a relative velocity of c or greater (which one would expect from a classical treatment of two particles heading towards each other, each with a speed of 99.999% c wrt the detector...)
For clarity in the rest frame of either proton the other proton will not appear to be moving greater than c towards it. In the laboratory frame the closing speed (the speed at which the scientists observe the two proton approaching each other) will be slightly less than twice c. This is acceptable because the closing speed of two moving objects is not an actual speed and proper use of the Lorentz transforms from the laboratory frame to the rest frame of either proton will give you the correct answer of a relative velocity less than c between the two particles.
There is no clarity in an inaccurate statement!
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You are again wrong the separation between the two protons "Is a Physical Thing" it is space-time and nothing can move through or approach each other at greater than c Period my friend!
Nope. The distance between two physical objects is not an object. It has no energy or mass and does not transmit information. It is nothing but some numbers an artifact of observation if you will.
There is no clarity in an inaccurate statement!
The statement was in fact accurate and well known to scientists that work with relativity.
I have a question for you. Do you think that given a strong enough laser we could create a spot of light on the Moon that would move across the Moon faster than the speed of light?
edit:
Oh and just so you know spacetime itself is perfectly able to move faster the c. It is only massive particles initially moving slower than c that can never move at or faster than c.
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I cant see how the scientist would observe the two opposing proton approaching each other "at almost twice c," when c is a universal constant unaffected from any view point, it always equal c or less never more, which is an impossibility?
The key is in the fact that the speed at which you see two separate objects moving toward (or away from) each other is not the speed of an actual object. It is the speed at which the distance between them shrinks (or grows) not the speed of any actual object. The scientists measures both protons as moving slightly less than c with respect to himself (or herself) but in opposite directions. As such the speed at which the protons approach each other is slightly less than twice c.
https://en.wikipedia.org/wiki/Faster-than-light#Closing_speeds <- A concise explination
Your Link to wikipedia below?
https://en.wikipedia.org/wiki/Faster-than-light#Closing_speeds
The rate at which two objects in motion in a single frame of reference get closer together is called the mutual or closing speed. This may approach twice the speed of light, as in the case of two particles travelling at close to the speed of light in opposite directions with respect to the reference frame.
Imagine two fast-moving particles approaching each other from opposite sides of a particle accelerator of the collider type. The closing speed would be the rate at which the distance between the two particles is decreasing. From the point of view of an observer standing at rest relative to the accelerator, this rate will be slightly less than twice the speed of light.
Special relativity does not prohibit this. It tells us that it is wrong to use Galilean relativity to compute the velocity of one of the particles, as would be measured by an observer traveling alongside the other particle. That is, special relativity gives the right formula for computing such relative velocity.
It is instructive to compute the relative velocity of particles moving at v and -v in accelerator frame, which corresponds to the closing speed of 2v > c. Expressing the speeds in units of c, β = v/c:
The supposed greater than c gap approach between the two protons, is a mathematical construct that does not that does not exist in the real world. It is an illusion of the observer!
Nothing can move through the fabric of space time a greater than c, although galaxies embedded into the fabric of space, can and are receding from each other at greater than c, because space is expanding at a greater and greater rate, taking galaxies with it like raisins in a loaf of bread. Like dots in a rubber band that is increasingly stretched, resulting in them moving away from each other.
To put it is the very simplest manner "The two protons approach each other at less than the speed of light", even though they have been accelerated to 9.99999999991%c from opposite ends of the collider , "the closing gap" has nothing to do with the impossibility of any object of mass exceeding the speed of light and a proton, has mass, does it not?
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The supposed greater than c gap approach between the two protons, is a mathematical construct that does not that does not exist in the real world. It is an illusion of the observer!
Oh you mean like I said here:
For clarity in the rest frame of either proton the other proton will not appear to be moving greater than c towards it. In the laboratory frame the closing speed (the speed at which the scientists observe the two proton approaching each other) will be slightly less than twice c. This is acceptable because the closing speed of two moving objects is not an actual speed and proper use of the Lorentz transforms from the laboratory frame to the rest frame of either proton will give you the correct answer of a relative velocity less than c between the two particles.
and here:
I reiterate that either proton will only ever see the other proton as moving at less than the speed of light. The people in the lab will also see both particles as moving less than the speed of light. However, the people in the lab will see that the distance between the particles is shrinking at faster than the speed of light. This is perfectly fine because the separation between two objects is not a physical thing and as such cannot be accelerated and strictly speaking does not have a speed. This is an artifact of the lab frame of reference not a property of the particles. However, it is a good idea to keep it in mind because it is a subtle thing and many people say very silly things because they don't understand the difference.
and here:
Nope. The distance between two physical objects is not an object. It has no energy or mass and does not transmit information. It is nothing but some numbers an artifact of observation if you will.
Normally I'd chastise you for not reading but clearly you did read because you said this:
You are again wrong the separation between the two protons "Is a Physical Thing" it is space-time and nothing can move through or approach each other at greater than c Period my friend!
So you were clearly aware that my point was that the distance between objects and thereby the speed at which that distance closes is purely mathematical and you clearly disagreed. The fact that you are saying the opposite now is highly dishonest and very suspect.
Nothing can move through the fabric of space time a greater than c, although galaxies embedded into the fabric of space, can and are receding from each other at greater than c, because space is expanding at a greater and greater rate, taking galaxies with it like raisins in a loaf of bread. Like dots in a rubber band that is increasingly stretched, resulting in them moving away from each other.
That's pretty much what I said here:
Oh and just so you know spacetime itself is perfectly able to move faster the c. It is only massive particles initially moving slower than c that can never move at or faster than c.
To put it is the very simplest manner "The two protons approach each other at less than the speed of light", even though they have been accelerated to 9.99999999991%c from opposite ends of the collider , "the closing gap" has nothing to do with the impossibility of any object of mass exceeding the speed of light and a proton, has mass, does it not?
No one ever disputed the fact that no one would ever see any individual proton as moving greater than c with respect to themselves irrespective of their reference frame. I simply pointed out that in the rest frame of the laboratory the distance between the two protons will decrease as slightly less than twice c. Everything else was you constructing strawman arguments that never existed.
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The supposed greater than c gap approach between the two protons, is a mathematical construct that does not that does not exist in the real world. It is an illusion of the observer!
Oh you mean like I said here:
For clarity in the rest frame of either proton the other proton will not appear to be moving greater than c towards it. In the laboratory frame the closing speed (the speed at which the scientists observe the two proton approaching each other) will be slightly less than twice c. This is acceptable because the closing speed of two moving objects is not an actual speed and proper use of the Lorentz transforms from the laboratory frame to the rest frame of either proton will give you the correct answer of a relative velocity less than c between the two particles.
and here:
I reiterate that either proton will only ever see the other proton as moving at less than the speed of light. The people in the lab will also see both particles as moving less than the speed of light. However, the people in the lab will see that the distance between the particles is shrinking at faster than the speed of light. This is perfectly fine because the separation between two objects is not a physical thing and as such cannot be accelerated and strictly speaking does not have a speed. This is an artifact of the lab frame of reference not a property of the particles. However, it is a good idea to keep it in mind because it is a subtle thing and many people say very silly things because they don't understand the difference.
and here:
Nope. The distance between two physical objects is not an object. It has no energy or mass and does not transmit information. It is nothing but some numbers an artifact of observation if you will.
Normally I'd chastise you for not reading but clearly you did read because you said this:
You are again wrong the separation between the two protons "Is a Physical Thing" it is space-time and nothing can move through or approach each other at greater than c Period my friend!
So you were clearly aware that my point was that the distance between objects and thereby the speed at which that distance closes is purely mathematical and you clearly disagreed. The fact that you are saying the opposite now is highly dishonest and very suspect.
Nothing can move through the fabric of space time a greater than c, although galaxies embedded into the fabric of space, can and are receding from each other at greater than c, because space is expanding at a greater and greater rate, taking galaxies with it like raisins in a loaf of bread. Like dots in a rubber band that is increasingly stretched, resulting in them moving away from each other.
That's pretty much what I said here:
Oh and just so you know spacetime itself is perfectly able to move faster the c. It is only massive particles initially moving slower than c that can never move at or faster than c.
To put it is the very simplest manner "The two protons approach each other at less than the speed of light", even though they have been accelerated to 9.99999999991%c from opposite ends of the collider , "the closing gap" has nothing to do with the impossibility of any object of mass exceeding the speed of light and a proton, has mass, does it not?
No one ever disputed the fact that no one would ever see any individual proton as moving greater than c with respect to themselves irrespective of their reference frame. I simply pointed out that in the rest frame of the laboratory the distance between the two protons will decrease as slightly less than twice c. Everything else was you constructing strawman arguments that never existed.
I have reported you to the moderator who do you think you are some sort of omniscient being to chastise and say people are posting highly suspect and dishonest nonsense You are wrong on this topic period? And tone down your rhetoric and stop all this unnecessary arrogance it is highly distasteful and does not belong on any forum of like minded people
Go elsewhere with your rants
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Moderator here.
I do not see anything particularly distasteful in agyeji's post, although it is perhaps somewhat more direct than I would have been...
As far as the science goes: agyeji appears to be presenting fairly mainstream and widely accepted views. As far as I can tell from reading this thread, Alan is confused by some aspects of special relativity (it is confusing stuff).
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I do not see anything particularly distasteful in agyeji's post, although it is perhaps somewhat more direct than I would have been...
I apologize for any inconvenience this may have caused as I may have over reacted. It is not very pleasant when someone says everything you just said and then claims you were wrong when you said it.
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Moderator here.
I do not see anything particularly distasteful in agyeji's post, although it is perhaps somewhat more direct than I would have been...
As far as the science goes: agyeji appears to be presenting fairly mainstream and widely accepted views. As far as I can tell from reading this thread, Alan is confused by some aspects of special relativity (it is confusing stuff).
Chris I beg to differ telling a me in his post "Is highly suspect and dishonest" when I was presenting my augment as I saw it, even if wrong, does not merit this type of ugly rhetoric!
It sounds more like what a judge or prosecuting lawyer would say to a suspected criminal, rather than to another member of a hopefully friendly forum of like-thinkers!
Alan
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I do not see anything particularly distasteful in agyeji's post, although it is perhaps somewhat more direct than I would have been...
I apologize for any inconvenience this may have caused as I may have over reacted. It is not very pleasant when someone says everything you just said and then claims you were wrong when you said it.
What if, hypothetically we used mountains, instead of protons, then the observer could see one mountain approaching him at say 90% c and the other mountain also at 90% c. The two mountains if they had the means to see each other, would still observe the other approaching at less than c (speed of light)
At this much larger scale a person could put himself between/middle of the two approaching mountains, at 90%c From his perceptive would the gap in which he has put himself shrink at greater than the speed of light or 180% c?
Alan
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At this much larger scale a person could put himself between/middle of the two approaching mountains, at 90%c From his perceptive would the gap in which he has put himself shrink at greater than the speed of light or 180% c?
Yes. It is important to keep in mind that closing speed and relative velocity are very different quantities calculated in very different ways. In Newtonian mechanics (or at least when Newtonian mechanics is a suitable approximation) there isn't actually a difference between the value of the closing speed and the value of the relative velocity of two objects but there is a very large difference between those values at relativistic speeds. This is the point I have been making from the beginning. It is very easy for someone to confuse closing speed and relative velocity because in basically all of our everyday experience there isn't any difference.
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At this much larger scale a person could put himself between/middle of the two approaching mountains, at 90%c From his perceptive would the gap in which he has put himself shrink at greater than the speed of light or 180% c?
Yes. It is important to keep in mind that closing speed and relative velocity are very different quantities calculated in very different ways. In Newtonian mechanics (or at least when Newtonian mechanics is a suitable approximation) there isn't actually a difference between the value of the closing speed and the value of the relative velocity of two objects but there is a very large difference between those values at relativistic speeds. This is the point I have been making from the beginning. It is very easy for someone to confuse closing speed and relative velocity because in basically all of our everyday experience there isn't any difference.
I understand it now! although reading about it there are some physicist that disagree with it "By the way I was not being dishonest", I put forward what I believe was true and I very seldom use Wikipedia as a reference, simply because I could have gone to the particular link you supplied and edited the article to concur with what I believed was accurate.
I would rather find my source from an accredited scientific journal, as an example!
Am I at last accurate as indicated below?
"The observer could measure the distance between the objects shrinking at >c. Note, however, that "the rate of distance shrinkage isn't actually the velocity of anything". "It's not even a velocity, though it does have the units of velocity. The objects themselves would measure each other to be moving at <c.
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I understand it now! although reading about it there are some physicist that disagree with it
I'd like to know which ones because you've either misunderstood what they were saying (in which case I can help), they are not very good physicists (in which case I suggest you not listen to what the say), or they aren't actually physicists are all.
I very seldom use Wikipedia as a reference, simply because I could have gone to the particular link you supplied and edited the article to concur with what I believed was accurate.
I would rather find my source from an accredited scientific journal, as an example!
For a report for school or in some professional capacity sure Wikipedia is a terrible choice. For an internet based forum discussion unless you can prove the entry has been manipulated there really isn't much harm in trusting it because generally speaking the wikipedia people do a fairly good job with non-controversial topics at least. That and you can always verify what was changed, when, and often by who as there are public records. Though independent verification is never a bad idea.
Am I at last accurate as indicated below?
"The observer could measure the distance between the objects shrinking at >c. Note, however, that "the rate of distance shrinkage isn't actually the velocity of anything". "It's not even a velocity, though it does have the units of velocity. The objects themselves would measure each other to be moving at <c.
That statement is correct.
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I understand it now! although reading about it there are some physicist that disagree with it
I'd like to know which ones because you've either misunderstood what they were saying (in which case I can help), they are not very good physicists (in which case I suggest you not listen to what the say), or they aren't actually physicists are all.
I very seldom use Wikipedia as a reference, simply because I could have gone to the particular link you supplied and edited the article to concur with what I believed was accurate.
I would rather find my source from an accredited scientific journal, as an example!
For a report for school or in some professional capacity sure Wikipedia is a terrible choice. For an internet based forum discussion unless you can prove the entry has been manipulated there really isn't much harm in trusting it because generally speaking the wikipedia people do a fairly good job with non-controversial topics at least. That and you can always verify what was changed, when, and often by who as there are public records. Though independent verification is never a bad idea.
Am I at last accurate as indicated below?
"The observer could measure the distance between the objects shrinking at >c. Note, however, that "the rate of distance shrinkage isn't actually the velocity of anything". "It's not even a velocity, though it does have the units of velocity. The objects themselves would measure each other to be moving at <c.
That statement is correct.
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I'd like to know which ones because you've either misunderstood what they were saying (in which case I can help), they are not very good physicists (in which case I suggest you not listen to what the say), or they aren't actually physicists are all.
Again you are right the guys/me who got this wrong are not physicists , in fact I am an engineer and amateur astronomer now retired.
My final word to really simplify the question.
"If you shoot two protons away from each other at 90% c, they would be separating from each other at 180%c from, the perceptive of an observer?"
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My final word to really simplify the question.
"If you shoot two protons away from each other at 90% c, they would be separating from each other at 180%c from, the perceptive of an observer?"
This one thing I would caution you about is the requirement of clearly stating a specific frame of reference. A more accurate and precise phrasing would be more like:
"If two protons that are initially at rest with respect to each other are accelerated such that they are now moving at 90% c in opposite directions the distance between them would be seen to increase at 180% c by an observer that was also at rest with respect to the protons before the acceleration."
This makes the specific reference frame very clear because not all reference frames will see the separation distance as increasing at 180%. The trivial example is when one is in the rest frame of one of the protons after the acceleration. In which case that proton isn't moving and the other is moving at less than c and thus their separation in that frame must also be less than c.
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Yet paradoxically if a person stood in the exact middle or path of the two mountains approaching him at 90% light speed, they would "crash" into him at a less than combined speed of light say 98% c?
Alan
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IMHO the way to understand this is to remember the wave nature of matter, and appreciate that if we were made of sound waves along with our rods and clocks, we would never measure our own speed as exceeding the speed of sound.
In similar vein you never measure your own speed to be exceeding c, even though in the relativistic rocket (http://math.ucr.edu/home/baez/physics/Relativity/SR/Rocket/rocket.html) you can "travel across the galaxy in just 12 years of your own time".
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By the way, if two light beams are heading towards each other at c, the gap between them is reducing at 2c. It's similar for protons moving towards each other at 0.9999c at the LHC. Their closing speed is just under 2c, even though the velocity addition formula (https://en.wikipedia.org/wiki/Velocity-addition_formula#Special_relativity) is applicable to the speed of one as measured by the other.
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IMHO the way to understand this is to remember the wave nature of matter, and appreciate that if we were made of sound waves along with our rods and clocks, we would never measure our own speed as exceeding the speed of sound.
So in effect what you are implying is that matter is made out of light waves. In which case everything in the universe is traveling at the speed of light. Nice one John.
In similar vein you never measure your own speed to be exceeding c, even though in the relativistic rocket (http://math.ucr.edu/home/baez/physics/Relativity/SR/Rocket/rocket.html) you can "travel across the galaxy in just 12 years of your own time".
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Yet paradoxically if a person stood in the exact middle or path of the two mountains approaching him at 90% light speed, they would "crash" into him at a less than combined speed of light say 98% c?
Alan
Each individual mountain would crash into him at 90% of the speed of light. I'm not sure what you mean by combined speed as it really isn't a scientific term (or at least I've never heard it) and as such I have no idea how one would calculate a "combined speed". Some quick googling turns up the "Combined Speed Formula" which law enforcement officers use to estimate the original speed of a vehicle in a complex accident but I don't think that it was you meant.
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According to a stationary observer, particle A move from left to right at 0.9 c while particle B move from right to left also at 0.9 c.
Let's assume particle A & B have the same mass, m.
According to a stationary observer, combined system of both particles have 0 total momentum.
If second observer move to the left at 0.9 c, what are the velocities of each particle, and what is the system's momentum according to him?