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Why is there a universal speed limit, c, and why is it what it is? 
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#19
Mar1011, 07:27 AM

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What am asking is the same way I would ask why is there a limit to how much mass an object can have, or why is there a limit to ow big and object can be, or why is there a limit to how fast something can spin? It seems there is not reason there should be limits, ad if there is what is limiting factor? What is causing the restriction? 


#20
Mar1011, 07:33 AM

P: 158

I hypothesize that it is not a random coincidence that the square root of (m/e) exactly equals the speed limit. I think there is some connection between matter and energy and the speed limit. 


#21
Mar1011, 07:36 AM

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Note that different people give different answers to that question, and probably nobody can prove to really have the right answer. Harald 


#22
Mar1011, 12:24 PM

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#23
Mar1011, 01:30 PM

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My answer here:
http://www.physicsforums.com/showthr...=478783&page=2 in CosmicVoyager's similar thread explains why c defines a limit. Why c holds the value it does, though, is a different matter entirely. Naturally, the units used are meaningless since metres are derived from the observed speed of light in vacuo and the second relates to Caesium decay. This means that the 2.99897(or whatever) ms^1 number is not significant as a quantity, but as a unique value, like PI (which is ultimately defined by the curvatre of spacetime), or the the natural logarithm/root, or the fine structure constant, or the universal gravitation, it has a special characteristic of being a constant (to our current understanding, theories of c variance notwithstanding) in our universe. Regardless of the wavelength of light, how much energy it has, it maintains the constant speed. Unlike massive objects for which the greater their mass, the more energy is needed. That bosons have a fixed speed, DeBroglie showed how E is related to wavelength as well as mass, giving a means to describe massless objects and waves with momentum equivalent to their massive counterparts. Introduxing Planck's constant, quantised the relativistic energy and allowed working with manifest in the same terms of energy and momentum as massive entities. ______ c=\/h^2.f.L That frequency and wavelength are related according only to c, c is directly dependant only on the value of another constant. 


#24
Mar1011, 01:47 PM

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#25
Mar1011, 01:49 PM

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#26
Mar1011, 01:54 PM

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#27
Mar1011, 03:09 PM

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#28
Mar1111, 03:45 AM

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CosmicVoyager, did I understand you correctly? Harald 


#29
Mar1111, 04:53 AM

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I suspect my paradigm might be completely wrong and I need to shift, in which case I need why it is wrong explained. It seems the same as if I were adding more and more to an object to increase it's mass, then suddenly the mass stopped increasing, and I think "What the heck is going on?" 


#30
Mar1111, 09:44 AM

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#31
Mar1111, 09:59 AM

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Quote: bcrowell
"Failing to spell out one's assumptions is simply sloppy reasoning" Or sloppy social skills, in comprehension. CAUTION: LOTS OF HOT AIR FROM AN ARMCHAIR I think it looks like cosmicvoyager is looking for an answer that works for him, a subjective one that works for his current understanding of his question. Many of the posts here more then answer his question. Chicken / egg sums it up. Here is my best attempt. CosmicVoyager, consider the relationship between time and speed. It is as much a "speed limit" as a "time limit". Or an "activity limit". to your own point space is a medium, "C" is the bandwidth of that medium. Why does the medium have a limit? I fall back to thinking about the theory of the universe expanding. I belive it is expanding at the speed of light. I also belive it is the medium itself that is expanding. Perhaps that theory comes before the "speed limit". Said differently, maybe something can't travel faster then the meduim is being "built". From there, let's turn the idea on its head. At rest we are travelling at the limit (with space itself as it expands) and its movement that reduces this effect. So from an observer perspective as something travels, towards "C", the limit, it is actualy, relative to the medium, traveling towards zero, also were time / activity stops. So an object moving at "C" is moving as fast as the medium (space). From the perspective of the medium "C" is not the maximum, its the minimum. And zero is the maximum. To reiterate points already made lets assume my suggested answer is fact. Your question still stands, however shifts to "why does expansion of the medium itself have a "speed limit"?". Anwsers have to have a context, and your question didn't provide one. Without context it can always be asked, "yea, but why?". 


#32
Mar1111, 11:18 AM

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#33
Mar1111, 12:02 PM

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All that I said was after my comment: CAUTION: LOTS OF HOT AIR FROM AN ARMCHAIR
2nd, the OP is playing imagination games, not condutcing physics experiements. The OP wasn't satisfied with replies that answered the question well, from a physics perspective. Also the question itself suggests a limited physics background. Therefore he must be asking from some other perspective, hence just some fun food for thought. Tearing apart my laughable post, is equaly laughable. It wasn't posted to see if it holds up to peer review. seems Im as bad at physics as you are with... 


#34
Mar1111, 12:33 PM

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#36
Mar1111, 01:32 PM

P: 158

"Your question still stands, however shifts to "why does expansion of the medium itself have a "speed limit"?"." It wouldn't for me. It does not have a limit. That speed is the result of whatever propelled the expansion. It could have been faster or slower. 


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