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Thread: Why is the speed of light 299 792 458 m / s?

  1. #1 Why is the speed of light 299 792 458 m / s? 
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    Why is the speed of light 299 792 458 m / s and not some other , higher or lower speed? How can I calculate the speed of light theoretically to get its correct value?
    (No experiments or stuff, just plain math.) Thx!


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    Without fully understanding all the details myself, Wiki does have a page explaining this. The short answer is that it comes from Maxwell's equations.


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    Quote Originally Posted by MagiMaster
    Without fully understanding all the details myself, Wiki does have a page explaining this. The short answer is that it comes from Maxwell's equations.
    Yes, but that then begs the question as to why the values for the permitivity and permeability of free space are what they are.

    The short answer is that nobody knows.
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    Recently the meter was defined to be the distance traveled by light in 1/299792458 second.
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    Quote Originally Posted by mathman
    Recently the meter was defined to be the distance traveled by light in 1/299792458 second.
    That pretty much answers and evades the question simultaneously.

    The interesting thing about the speed of light is not its value, but rather its invariance with respect to a choice of inertial reference frame.
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    Thanx guys!
    I had a strange idea the other night. I just started thinking about this and then I tried to understand the possible reasons why such a limit would exist. Taking the many-worlds theory is correct and there is an infinite number of dimensions, any dimension you could imagine does in fact exist somewhere. For example, the universe of Star Wars or Lord of the Rings and all of those people and their world's laws actually exist. So there is an Anakin who is fighting Obi-wan "just now" somewhere. But lets return to the mentioned idea. If the speed of objects in an inertial frame of reference, relative to any other, is the cause of the objects going relatively forward and backward in time. One would agree that time travel on such a basis does not exist, but is rather reduced and simplified to dimension jumps ( objects changing their current dimensions and "jumping" from one to the other. Assuming the dimensions are almost 100% the same, and thus have a law of dimensional entanglement which would state that objects cannot jump from one dimension to a completely different one, but rather to a similar or almost identical dimension ). As time travel is reduced to spacetime travel, the question is where are those dimensions and how far are they from each other? A planck length perhaps, separating dimensions and making them compressed, same-space occupying information in a 11-dimensional universe described in M-theory with the information being kept in the 5+ dimensions on the string size level? I came to the idea that objects are always jumping from dimension to dimension and that timeflow and the speed of light are defined by the speed of this transpassing, which "gates" or "distances between dimensions" are limited in size because of their own existance , that in turn limits the size. In conclusion, light's speed and the other constants like vacuum permeability and permitivity are all derivations of a constant which I would call "interdimensional flow speed" Here timeflow is quantized and limited by the size of a unit or packet.

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    If you are curious why and other constants are what they are, you may want to have a look at the Anthropic Principle.

    I haven't read the Wikipedia article in full, but I notice a strange use of modes and tenses in one paragraph:

    If the universe were one tenth as old as its present age, (...)
    If the universe were 10 times older than it actually is (...)
    IMHO, this should read "When the universe was..." and "When the universe is...".

    Just my PLN0.02.
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    Quote Originally Posted by Leszek Luchowski
    If you are curious why and other constants are what they are, you may want to have a look at the Anthropic Principle.

    I haven't read the Wikipedia article in full, but I notice a strange use of modes and tenses in one paragraph:

    If the universe were one tenth as old as its present age, (...)
    If the universe were 10 times older than it actually is (...)
    IMHO, this should read "When the universe was..." and "When the universe is...".

    Just my PLN0.02.
    IMO the "anthropic principle"is the biggest cop out in the recorded history of science. There is an entire, bad, book on the subject. If reading that book does not make one nauseous, it will surely put one to sleep.
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    Quote Originally Posted by Leszek Luchowski
    If you are curious why and other constants are what they are, you may want to have a look at the Anthropic Principle.

    I haven't read the Wikipedia article in full, but I notice a strange use of modes and tenses in one paragraph:

    If the universe were one tenth as old as its present age, (...)
    If the universe were 10 times older than it actually is (...)
    IMHO, this should read "When the universe was..." and "When the universe is...".

    Just my PLN0.02.
    I'm pretty sure that the anthopic prinicple falls more under philosophy rather than science, but the wording's right (if confusing) since it's talking about hypothetical universes, not the past or future of the current universe.
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    I checked out the wiki on "anthropic principal". The WAP seems pretty basic. To paraphrase; we're here and we see what we see. Boy, that took some genius to figure out!(NOT!) The rest of it seem's like numerology, or astrology, or alchemy, or something.

    Now, when we're talking about "free space", are we talking about space that is completely free of any energy or matter? Is there a difference in the permittivity and permeability of a cubic meter of space containing one hydrogen atom and another cubic meter of space containing two hydrogen atoms?
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    Ohh I have an answer for this one.

    The speed of light is the exact speed we have come to know it as because the Reality 1.0 life simulator wasn't able to process anything faster at the time with respect to other changes. They also didn't feel the need to slow everything else down in order to create the perception of even greater speed. When Reality 1.1 came about with faster processors the "creators" decided to maintain the reference point so as not to interfere with the simulation.

    OK, I didn't say it was a good answer
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    Why is Light the speed that it is?

    Because it's arrogant, but also lazy

    It's arrogant and has to be faster than everything else, but it can't be arsed to go faster than it currently does because it's worked out darkess will always beat it there



    In all honesty there isn't a 'reason' for it's speed (the actual number has reason, namely human and mechanical error and suchlike) it's just what it is, same as there's no 'reason' dark matter is physically invisible, or 'reason' the universe started 14Billion years ago.


    well, there probably are, but no one knows (if you find the answer, let me know K?)
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    I, on the other hand, happen to like the elegance of the Anthropic Principle. It does not state 'we are here and we see what we see', but rather things are what they are ,including the speed of light, because if they were different, life (and the universe) would not have developed as it has and we would not be here to observe things (or measure the speed of light as c). Its .a circular argument to be sure but true nonetheless since a lot of the constants that we measure, such as c., h, g, etc. are very fine-tuned and if even slightly different, may have caused a totally different universe, a still-born, lifeless universe or even a recollapsed universe which never expanded.
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    Quote Originally Posted by MigL
    I, on the other hand, happen to like the elegance of the Anthropic Principle. It does not state 'we are here and we see what we see', but rather things are what they are ,including the speed of light, because if they were different, life (and the universe) would not have developed as it has and we would not be here to observe things (or measure the speed of light as c). Its .a circular argument to be sure but true nonetheless since a lot of the constants that we measure, such as c., h, g, etc. are very fine-tuned and if even slightly different, may have caused a totally different universe, a still-born, lifeless universe or even a recollapsed universe which never expanded.
    That is not elegance, but rather a cop out. It is in fact a non-explanation designed to transform "why?" into "why not ?".

    The anthropic principle has become popular among string theorists as a result of the abject failure of string theory to fulfill its early promise to demons rate a unique mathematically consistent theory in which the fundamental physical constants would be logically required to be as observed. But now, despite the lack of even one well-defined theory string theorists claim the existence of something like 10^500 consistent theories and claim, on the basis of aesthetics that ALL of them must represent reality somewhere. Then to explain why we see what we do see the anthropic principle is invoked. The result is a mishmash that is not testable, even in principle, and that can explain ANYTHING. Unfortunately since the string theorists cannot produce a specific model among the 10^500 supposed candidates that describes the universe that is actually observed it explains nothing.

    Elegant? Hardly.
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    Quote Originally Posted by MagiMaster
    Quote Originally Posted by Leszek Luchowski
    I haven't read the Wikipedia article in full, but I notice a strange use of modes and tenses in one paragraph:

    If the universe were one tenth as old as its present age, (...)
    If the universe were 10 times older than it actually is (...)
    IMHO, this should read "When the universe was..." and "When the universe is...".

    Just my PLN0.02.
    I'm pretty sure that the anthopic prinicple falls more under philosophy rather than science, but the wording's right (if confusing) since it's talking about hypothetical universes, not the past or future of the current universe.
    Well there might or might not be other Universes out there (wherever that is), older or younger, but we know that this Universe of ours has been younger and will be older.




    DrRocket: we may be witnessing an argument similar to Paley's watch, or actually another round of the same discussion.

    The former round, solved by Darwin, ran more or less like this (putting it in badly oversimplified terms):

    - How could complicated organisms, with cells and organs so precisely tuned for life, arise without an Intelligent Designer?
    - Because there were a lot of them and the less well tuned died.

    This one goes:

    - How could a complicated Universe, with all physical constants so precisely tuned to support life, arise without an Intelligent Designer?
    - Because there were/are a lot of them and the less well tuned were never observed.

    I'm not taking any position in this debate, I'm just saying this discussion might be what is going on.
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    Who are we to say that consciousness(cogito ergo sum) would not arise in a universe governed by a variant set of fundamental physical constant's? Perhaps there is "red" or "blue" grass growing over the septic tank, not just the "green" variety?

    P.S. I submit the word "Heteroverse(singular), Polyverse(plural)" for reference to alternate universe's, as opposed to using "Dimension(s)" which should be reserved for discussions of analysis(The two dimension's of the Euclidean plain. The three dimensions of Gallileon three-space. The four dimension's of space-time. The eleven dimension's of M-theory. Etc...).
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    Quote Originally Posted by Leszek Luchowski

    DrRocket: we may be witnessing an argument similar to Paley's watch, or actually another round of the same discussion.

    The former round, solved by Darwin, ran more or less like this (putting it in badly oversimplified terms):

    - How could complicated organisms, with cells and organs so precisely tuned for life, arise without an Intelligent Designer?
    - Because there were a lot of them and the less well tuned died.

    This one goes:

    - How could a complicated Universe, with all physical constants so precisely tuned to support life, arise without an Intelligent Designer?
    - Because there were/are a lot of them and the less well tuned were never observed.

    I'm not taking any position in this debate, I'm just saying this discussion might be what is going on.
    The anthropic principle is sometimes invoked by those whose stance on atheism is so strong as to make atheism a religion in itself. The idea is that it "explains" the apparent fine tining of the physical constants which are necessary for life as we know it.

    It falls short for several reasons. First, it does not really explain anything because it makes no testable predictions. It is just an unverifiable story, no different from mythology or religion.

    Second it proposes no mechanism whereby multiple universes would exist and against which the anthropic principle might be applied. This problem distinguishes it from Darwinian evolution which does come equipped with such a mechanism.

    Most importantly it is a thinly disguised attempt to answer WHY the universe is what it is rather than the scientific question of HOW the universe behaves as it does given some set of circumstances. The question of WHY is a question for philosophy and religion -- disciplines that never produce real conclusions but only foster dialog.

    So while the intent is to eliminate any suggestion of a designer, it fails. It fails in no small part because the question of the existence of God is one that science cannot answer -- neither affirmatively nor negatively.

    So ultimately the anthropic principle is a cop out. It isn't even science. Even were it correct, it would not be science because it is not testable so one could not show that was right.

    It is a philosophical issue, along with the determination of how many angels can dance on the head of a pin.
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    The question is not answered: why is the speed of light 300,000 kilometers per second?

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    Quote Originally Posted by jsaldea12
    The question is not answered: why is the speed of light 300,000 kilometers per second?

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    Read the thread.

    It is not answered because there is no answer.

    Moreover, "why?" is a question for philosophers. Scientists address "how ?".
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    Quote Originally Posted by DrRocket
    Moreover, "why?" is a question for philosophers. Scientists address "how ?".
    So, "why do apples fall from trees" is not a scientific question?

    Leaving aside the anthropic principle, I can't see what would be unscientific about seeking a reason for to be what it is.

    There was a time when we accepted that apples fall because they do.

    Then somebody thought there might be something that makes them behave in that way. And we learned about the mass of the apple and the mass of the Earth, and that there is a law that says masses attract. And then for a long time we acceptet that that is the law, period.

    Then somebody started asking why masses attract, and we learned about space-time curvature.

    Then, AFAIK, somebody asked why anything has mass to begin with, and they started building huge accelerators looking for some elusive particles.

    In my opinion, "why" is a very scientific question. Perhaps _the_ most scientific of all.

    The question "why do physical constants (in our universe) have the value they do" might be impossible to answer by our scientific means, as we have very few universes to work with and even fewer tools to manipulate the one we have. But that does not make the question unscientific. If ancient philosophers wondered what the other side of the moon looks like, they were asking a scientific question; and it would have been one even if humanity were to never invent rockets.
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    Quote Originally Posted by DrRocket
    It is a philosophical issue, along with the determination of how many angels can dance on the head of a pin.
    Actually, that was "be", not "dance". Dancing means motion, which would require some room. And it was the tip of the pin, not its head.

    And finally, it was not a philosophical or theological question any more than "how many apples are two apples and three apples" is a botanical question.

    It was a mathematical issue, using the example of angels as familiar (to the people of the time) zero-sized beings on the familiar zero-sized area of the tip of a pin. As angels don't have bodies, they can be thought of as being, physically, infinitely small.

    To rephrase the question in modern language: "how many points are there in an infinitely small area" - which is a question not unlike "is there a cardinality greater than but smaller than ?". Some people shrugged it off as laughable and pointless. But some didn't, and one of them was Kurt Goedel.
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    Quote Originally Posted by Leszek Luchowski
    Quote Originally Posted by DrRocket
    Moreover, "why?" is a question for philosophers. Scientists address "how ?".
    So, "why do apples fall from trees" is not a scientific question?

    It can be scientific if it really means "How is the falling trajectory determined by gravity ?" and not "Why does gravity exist ?"

    Don't split hairs like a philosopher.
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    Quote Originally Posted by Leszek Luchowski
    Quote Originally Posted by DrRocket
    It is a philosophical issue, along with the determination of how many angels can dance on the head of a pin.
    Actually, that was "be", not "dance". Dancing means motion, which would require some room. And it was the tip of the pin, not its head.

    And finally, it was not a philosophical or theological question any more than "how many apples are two apples and three apples" is a botanical question.

    It was a mathematical issue, using the example of angels as familiar (to the people of the time) zero-sized beings on the familiar zero-sized area of the tip of a pin. As angels don't have bodies, they can be thought of as being, physically, infinitely small.

    To rephrase the question in modern language: "how many points are there in an infinitely small area" - which is a question not unlike "is there a cardinality greater than but smaller than ?". Some people shrugged it off as laughable and pointless. But some didn't, and one of them was Kurt Goedel.
    rubbish.

    I AM a mathematician. Don't try to teach your grandmother to suck eggs.

    The last question you describe is the cintinuum hypothesis and has nothing to do with the earlier question. BTW the continuum hypothesis was shown to be independent of the usual Zermelo-Fraenkel axioms of set theory by Paul Cohen and others.
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    DrRocket, I am not trying to teach you mathematics. I wouldn't dream of doing that.

    I am trying to dispel a common stereotype about medieval scholars. While the angels-on-needletip question was not nearly as precisely posed as the continuum hypothesis, I claim it was an early step in that mathematical direction, and not a crazy theological excercise.
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    Why the speed of light is 186,000 miles per/sec.? That the speed of light is average of 186,000 miles is an evidence of the universal existence of spacetime of Dr. Einstein. It is like water in pond. Throw a stone and it will cause ripples on the water. Throw an impingement/spark on the universal spacetime and it will cause ripples all over at the speed of 186,000 miles per/sec. Why 186,000 miles per sec. It shows just how tense is the spacetime, which occupies completely all space, including outer space, and interior of atoms. It is just like tense guitar string that when it is twang, it vibrates from end to end. The same with light, it vibrates over the spacetime.See.

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    Why the speed of light is 186,000 miles per/sec.?
    I am an American, and horrified that my country chooses to remain in the dark ages and not progress to the standard of SI. From the grammatical structure of your post I am guessing that English is not your primary language, so why then do you insist on encouraging the heathen's?
    It shows just how tense is the spacetime, which occupies completely all space, including outer space, and interior of atoms. It is just like tense guitar string that when it is twang, it vibrates from end to end. The same with light, it vibrates over the spacetime.See.
    By assigning spacetime a physical quality(like shear modulus) the principal of relativity(Regardless of the inertial frame of reference c will measure) is violated. Under that condition we should be able to measure the motion of the earth relative to spacetime, but in truth no such measure exist's. See here http://en.wikipedia.org/wiki/Michael...ley_experiment.
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    Do you believe that spacetime of Dr. Einstein exists? That it is constant, inspite of ripples/impingements on it, it is not moved, but simply waves can be created thereat. Just like waves on water, the waves moves but the water remains as is, thus, how can you detect that which does not move? But it is there. Modern science has been trying to detect spacetime in exploding novas, trying to see (lensing) in clusters of galaxies, etc. extremely difficult but It is there. There is no such thing as perfect vacuum.

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    Nevermind.
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    Yes, but that then begs the question as to why the values for the permitivity and permeability of free space are what they are.

    The short answer is that nobody knows.
    Nobody knows, but from an EM viewpoint, they seem to describe properties of spacetime itself.

    Wave Theory (meaning here that fundamental theory to do with the generic propagation of any wave through any medium, and on which sound wave propagation and electromagnetic wave propagation are both based) tells us that there for a wave to propagate it must have an elastic property that serves to restore a displacement, and an inertial property that serves to resist acceleration.

    Although EM waves are more complex than sound waves, the generic propagation rules apply. Inverse permittivity acts as a restoring force and permeability as an inertial force. The implication is these they are fundamental aspects of space itself in the same way that inertia and elasticity are fundamental properties of materials that carry sound waves. These properties are at a more fundamental level than matter or electromagnetism, being intrinsic to spacetime itself.

    Unfortunately that gets us nowhere.
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  31. #30 Re: Why is the speed of light 299 792 458 m / s? 
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    Quote Originally Posted by EAS
    Why is the speed of light 299 792 458 m / s and not some other , higher or lower speed? How can I calculate the speed of light theoretically to get its correct value?
    (No experiments or stuff, just plain math.) Thx!
    A better question would be: why is a meter defined as being the distance a beam of light travels in 1/299,792,458 of a second? The fault for this value being such an arbitrarily weird number lies with us humans, not with the universe. If we chose better units of length and time, then light would appear to travel at a more sensible speed.

    For example, we could define our unit of length as being a "fromptorg", and set its length to be 2.99792458 meters , and our unit of time as being a "bugabee" and set its duration to be 100 seconds. If we did so, then we would be able to say that light travels at exactly a million fromptorgs per bugabee. Would that that be better?


    Answer:

    A meter was chosen as our unit of length because it is 100 times the length, height, or width across a cube of water that weighs one gram.
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    And than comes a question of why is gram chosen as unit of mass. Simply, we didn't have the knowledge we have today when we chose our units. That's why constant are- constants. They are here to modify our units.
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  33. #32 Re: Why is the speed of light 299 792 458 m / s? 
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    Quote Originally Posted by kojax
    A meter was chosen as our unit of length because it is 100 times the length, height, or width across a cube of water that weighs one gram.
    Actually, it was the other way round. The gram was originally defined as 1/1000th of the weight of a litre of water, a litre being 1/1000 cubic metre.

    The metre was defined as 1/40,000,000th of the perimeter of the Earth (I forget in which direction - I know the Equator is not the same length as the meridians).

    The second is, of course, of the average day and night period on the Earth.

    None of these references (the duration of the day, the size of the Earth, the density of water) is directly related to the speed of light, so no wonder that speed came out as an "inelegant" number.

    However, if we followed the consequences of relativity, including the idea of space and time being one continuum, we'd end up measuring distances and durations in the same unit. In which case, the speed of light would be expressed by the exquisitely simple number 1.
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    The Anthropic principle simply says that the laws of the universe must satisfy both cognitive and observational constraints. If the anthropic principle were incorrect than we wouldn't be able to establish mathematically proof-derived relationships with scientific phenomena.

    The answer to the question in the opening thread can be given as such: if we find that the energy content of any mass is governed by the formula , than we have that the constant c, the speed of light, is equal to , and it happens to the be case that this is about 299 792 458 m/s for any object. Now this doesn't get the heart of the problem of why the speed of light is what it is, but this reasoning still works, just as, in both mathematic theorems and philosophical arguments one must only provide one proof to validate or invalidate the conjectures of a theorem.
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    Still it,s possible to see what happens if you do this math when you use a different C.

    Meters/sec , time is distance, time in seconds-distance has also be adapted.

    For instance something meassured as five seconds distance then becomes a longer or shorter distance in time to the distance in meters then two clock's would indicate visually seen and spoken. Distance as time can,t be meassured with one clock. For instance meassuring the distance between a lamp and a receptor at a distance you can do this in meters first...Distance in meters.
    Then meassuring in seconds you need to clock when the device sends the signal and when the recptive side observes it.

    On Longer distance you can,t do this with one clock. It,s possible to stand somewhere in the middle and have a receptor there also. Time when the signal is received and when the other receptor now is a mirror time also when it comes back.

    If the distance between the mirrors would be one second. Then the time between the two signals (one from the mirror one directly) has a ratio 3/1. Meaning the trajektory from the transmittor to the mirror =1 s and back is 1/2 sec...total 1,5 sec.
    The directly incoming signal is 0,5. 1,5 - 0,5 distracts the distance from the observer in the middle to the transmitter from 2*0,5 for the distance back an forth to the mirror.

    Not the distance between the transmitter and the mirror is measured but the distance between the observer in the middle and the mirror is meassured as 2*0,5 sec.

    And this distance in sec then correlates with the measurement in meters.

    But the distance to the transmitter is not given by this in seconds. Only if knowing the distance in Meters to the source the distance in seconds can be calculated by this ratio. In this case it,s twice the distance in meters so twice in seconds also as the ratio stays constant.

    The same thing can be done with accoustic clocks and soundspeed no problem for a difference between experiemental outcome and relativistic math then.

    The only thing that makes it conflikt anthropic principle is when for a certain distance the distance in time is not also adapted. You have to adapt this also so meassure the distance for sounds in secconds also with accoustic clocks....then what come out is a striking similarity and the math is not susceptive to this.

    Where sec is used you only have to adapt with the ratio soundspeed / lightspeed.
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  36. #35  
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    Quote Originally Posted by Ghrasp
    Still it,s possible to see what happens if you do this math when you use a different C.

    Meters/sec , time is distance, time in seconds-distance has also be adapted.

    For instance something meassured as five seconds distance then becomes a longer or shorter distance in time to the distance in meters then two clock's would indicate visually seen and spoken. Distance as time can,t be meassured with one clock. For instance meassuring the distance between a lamp and a receptor at a distance you can do this in meters first...Distance in meters.
    Then meassuring in seconds you need to clock when the device sends the signal and when the recptive side observes it.

    On Longer distance you can,t do this with one clock. It,s possible to stand somewhere in the middle and have a receptor there also. Time when the signal is received and when the other receptor now is a mirror time also when it comes back.

    If the distance between the mirrors would be one second. Then the time between the two signals (one from the mirror one directly) has a ratio 3/1. Meaning the trajektory from the transmittor to the mirror =1 s and back is 1/2 sec...total 1,5 sec.
    The directly incoming signal is 0,5. 1,5 - 0,5 distracts the distance from the observer in the middle to the transmitter from 2*0,5 for the distance back an forth to the mirror.

    Not the distance between the transmitter and the mirror is measured but the distance between the observer in the middle and the mirror is meassured as 2*0,5 sec.

    And this distance in sec then correlates with the measurement in meters.

    But the distance to the transmitter is not given by this in seconds. Only if knowing the distance in Meters to the source the distance in seconds can be calculated by this ratio. In this case it,s twice the distance in meters so twice in seconds also as the ratio stays constant.

    The same thing can be done with accoustic clocks and soundspeed no problem for a difference between experiemental outcome and relativistic math then.

    The only thing that makes it conflikt anthropic principle is when for a certain distance the distance in time is not also adapted. You have to adapt this also so meassure the distance for sounds in secconds also with accoustic clocks....then what come out is a striking similarity and the math is not susceptive to this.

    For where sec^2 is used you only have to adapt one time with the ratio soundspeed to lightspeed. The other sec is read/meassured with the clock at such a short distance that this is neglected with light so if not neglected also for other C,s it won,t fit.
    Please go read a physics book.
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    For E=MC^2

    Cs^2----> 340^2

    A second for accoustic "realm" is a 299 792 458/340 times shorter distance to a distance in meter then for light.
    That,s 340/299 792 458 times longer.
    Therefor the denominator S1*S2 has to be multiplied with 340^2 / 299 792 458^2 to translate to accoustic clocks.
    Resulting :
    E=M * 340^2 * 299 792 458^2/340^2= M * 299 792 458^2.
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  38. #37 Re: Why is the speed of light 299 792 458 m / s? 
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    Quote Originally Posted by EAS
    Why is the speed of light 299 792 458 m / s and not some other , higher or lower speed? How can I calculate the speed of light theoretically to get its correct value?
    (No experiments or stuff, just plain math.) Thx!
    To ask this question is to suggest it was set for some reason, ie that it was designed, suggesting a superior being. Any units you choose to describe the rate of motion of a photon will be man made, so pick our own 'speed' such as 7o/sec.
    Where o = orbital path length of an object orbiting the earth some 266 miles above it's surface. thus 7 orbits per second
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    A better way to say how C works, is to just say that all speeds are fractions of C. I mean, think about it: if C is the highest possible value, and zero is the lowest possible, then there is no reason for us to speak of traveling at say 2.99 million meters/second. Instead, we would to better to call that traveling at 1/100 C.

    Basically, there is no such thing as an absolute velocity, only a relative velocity.


    Quote Originally Posted by Ghrasp
    Still it,s possible to see what happens if you do this math when you use a different C.
    If you used a different value of C, but kept the absolute velocities the same, like if you used 149 million meters per second, instead of 299 million meters per second as your C, but said the object were moving at 2.99 million meters per second, then you're right you'd get a different value.

    However, if you used relative velocities, then 2/100 C is twice as fast as 1/100 C. Clearly, if the value of C were to change, then the whole universe would rearrange itself to compensate. If C were half as fast, then your concept of time would be half as fast and you wouldn't notice the change.
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  40. #39  
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    For sound the ratio C is different, m/s is lower value but sec/meter (to calculate a rationumber from a laboratory meassurements for sec's and meters) it would reverse....sound has higher value for sec/m (sec to meter) then ; don,t loose the ratio with calculating a rationumber.

    Therefor for this case of clocks that can only be experienced by hearing the rationumber also applies to the seconds. That,s a good thing because otherwise fish in water (different C) would be at all places.
    One event would start happening at different places for blind then for deaf people...

    The most confusing here (to combine, relate to L*f and n*L*f) is maybe to regard a wavelength as a property of a foton. Instead of distance between fotons. Fotons are considered mathematical points and wavelength has meters as unit. Who could make a sweater out of that.
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  41. #40  
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    If C were half as fast, then your concept of time would be half as fast and you wouldn't notice the change.
    Isn,t this a bit strange ? If two clocks are compared from a further distance an accoustic clock and a visional one. Are they at different locality because of this ? If not then time is not faster or slower for one or the other either. Because then they where at different lokality.
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  42. #41  
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    Maybe I can help here. We use the motion of light to define our time and distance. We really do. Look at wikipedia for the definition of the second:

    "Since 1967, the second has been defined to be 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".

    For the background to this, check out the NIST caesium fountain clock, and read how lasers and a microwave cavity are employed to cause hyperfine transitions, which are electron “spin flips” within caesium atoms. The hyperfine transition emits microwaves, which is light in the wider sense. There’s a peak frequency in the emitted light, which is found and measured by the detector. But note that frequency is measured in Hertz, which is defined as cycles per second, and the second isn't defined yet. What the detectors really do, is count incoming microwave peaks. When they get to 9,192,631,770, that's a second. Hence the frequency is 9,192,631,770 Hertz by definition. Then we use the second along with light to define the metre:

    "Since 1983 the metre has been defined as the distance travelled by light in vacuum in 1⁄299,792,458 of a second".

    This next bit is crucial: the electron can be quite literally "made from light" via pair production, and electron/positron annihilation gives you the light back. Since the electron has its spin angular momentum and magnetic dipole moment, you can assert that at some primitive level the hyperfine transition is in essence an electromagnetic motion, essentially light moving, just like the emitted microwaves. And since we can do low-energy proton/antoproton annihilation to gamma photons (see below), you can say it's all light in the wider sense. So if c = √(1/ε0μ0) wasn't really constant, but everything is "made from light" including electrons and protons and rods and clocks and you and your brain, how are you going to tell?

    Think it through. Then ask yourself why we always measure the local speed of light in vacuo to be the same old 299,792,458 m/s. It's because we use the motion of light to define the second and the metre, which we then use... to measure the motion of light.


    Image credit: CSIRO, see http://www.csiro.au/ and http://outreach.atnf.csiro.au/educat...e/bigbang.html
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  43. #42  
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    This is another definition :

    The metre is the length of the path traveled by light in vacuum during a time interval of 1/299. 792 .458 of a second.
    According to this "definition" meters are described as meters/second in the realm of vision. 1m / {1/299 792 458) (m/s) not (m).

    This is not a meter as a length like a road that has to be travelled. it,s allready distance not symmetric or reversible.
    This description (m) per second (as the idea of speed m/s due to thinking this meter as length) units are m/s^2 not m/s.
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  44. #43  
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    A b s o l u t e S p a c e
    A n d t h e S p e e d o f L i g h t

    The Lorentz derivation left
    Absolute space behind,
    Given the assumption
    That measurements
    Are limited to 3 dimensions.

    Relativity provides computational capability,
    But does not give us access
    To the underlying reality,
    Yet, there is a reason that
    The speed of light
    Is the universe’s maximum speed,
    And why the internal change of a system
    Approaching the speed of light slows to zero.

    The speed of light is not merely
    A universal constant,
    But is the linear,
    Dimensional relationship
    Between space and time.

    There can be only one such relationship,
    And thus there is only one speed
    For the propagation of energy through space.

    Object moving at speeds less than ‘c’
    Are amalgamations of
    Static (particles cores)
    And dynamic (photon/kinetic) energy.

    The observed “time dilation”
    In object moving through absolute space
    Is solely a product of
    The universe’s photonic speed limit.

    A moving object is composed of
    Static (rest) and dynamic (propagating) energy.

    Its net motion through absolute space
    Constitutes the external manifestation
    Of its dynamic energy, herein called V.

    Any motion of its dynamic constituents
    Normal to V has no measurable effect
    On the net motion of the entire object,
    This motion being called Vi.

    Since ‘c’ is the metric of
    Energy’s propagation through absolute space,
    And since the external and internal components
    Of an object’s dynamic energy
    Are perpendicular to each other,
    Their relationship to each other
    Can be depicted as a triangle.

    height: Vi, length: V, diagonal: ‘c’

    The speed of an object’s internal motion
    Defines the rate
    Of the internal changes it experiences,
    Such as the decay period
    Of an unstable relativistic particle.

    An object’s internal motion
    Is related to its external motion by

    Vi^2 = c^2 - V^2

    The speed of light, ‘c’,
    Is the metric of all change;
    A motion of zero represent no change;
    A motion of ‘c’ is maximum change.

    The normalized rate
    Of an object’s internal change
    Is the ratio
    Of its internal components
    To the speed of light.

    Ri = Vi/c

    When Vi = 0
    Then Ri, the rate of internal change,
    Goes to zero.

    The relative length of a unit time interval
    In this system is the magnitude
    Of its “time dilation”, TD,
    This being the inverse of
    The rate of internal change, Ri.

    TD = T/T0 = 1/Ri = c/Vi,

    where T0 is the length
    Of a time interval at rest (V=0).

    If internal change is reduced
    To half of normal, for instance,
    An internal event takes
    Twice as long to occur.

    Substituting and solving, we get

    T/T0 = TD =

    1/[square roof of(1-V^2/c^2)]

    Which is the same “time dilation”
    Given by the Lorentz transformation,
    Yet, it is based solely
    On the real, physical limitations
    Of a moving system,
    No reconfiguration of
    Space and time being necessary.

    As the external motion goes to ‘c’,
    The rate of internal motion goes to zero.

    Velocity addition can also express ‘c’,
    By performing two
    Successive Lorentz transformations,
    For a V of V1 and V2,
    This being the addition of ratios,
    Not magnitudes, giving

    V = (V1+V2) / [ 1+ (V1*V2/c^2) ] =

    (c+V2 / c+V2 ) = c

    Thus, the speed of light
    Appears the same way in any direction
    In any moving reference frame.

    Velocities could not add
    Exactly like distances unless ‘c’ = infinity,
    There then being no upper limit
    To their magnitudes.

    So, vector addition could not be used,
    Due to the dimensional relationship
    Between time and space,
    Although it could be an approximation
    For adding velocities.
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  45. #44  
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    Yep, hence the Simple inference of time dilation.

    Public domain image by mdd4696.

    The Lorentz factor used in is derived from Pythagoras's theorem.

    NB: you should try to write in simple conversational English, questor, and try to use LaTex. The appearance of your post above is somewhat off-putting.
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  46. #45  
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    Hi Farsight; I was austintorn at ToeQuest, and remember you. Not much traffic at TQ any more. It's turning into GodQuest.
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  47. #46  
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    Hi questor/austintorn. I thought we might have met elsewhere. Shame about the "Godquest" thing. IMHO there's quite enough mysticism in physics as it is.
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  48. #47  
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    Yes, indeed. I'll start a thread called 'Amending Immaterial Science'. Maybe we'll get back to the real, such as electrons really orbiting, explaining spooky action at a distance, no aether wind, etc.
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  49. #48  
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    I took a look, questor. That "poetic" form really doesn't work. It damages your too-much-mysticism-in-physics argument so much that nobody will take it seriously. So my advice is this: snap out of it, and write sincere straight posts. Sorry to be blunt.
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  50. #49  
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    That form is only for readability, via line breaks.

    Not a poem. No rhymes, no meter, no rhythm, no certain amount of syllables, etc. It reads like prose.
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  51. #50  
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    No. It doesn't. It makes your posts more easily ignored. It's time to adjust your style if you want people to actually read what you type.
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  52. #51  
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    questor, your stuff is good, but I agree with the other posters, it is not reader friendly.
    .
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  53. #52  
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    OK, I'll work on it. Will just use that form for real poems or just for some longer, older reference material that may be in that form. Comes from being a poet. Thanks.
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