Speed of Light: A universal Constant?
in [Relativity]
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From: G on 26 Apr 2005 00:09 Ghost Thanks for your response. I thought no -one was listening (LIKE SETI?). . > In BaT, lightspeed is c relative to the source, *not* to > the destination (unless said destination is motionless > relative to the source). > > In SR/GR, lightspeed is c everywhere. OK > That's probably the primary difference between these two theories. > > > I can't see how the above statement could be true. Think of > > the speed of light as a messenger and the source as the message > > sender. > > You may be slightly confused. The speed of light is merely a > measurement constant. If you're referring to the light *pulse* > as being a message, that's fine. What is the speed of light? I mean what is the definition? Let me see the Wiki http://en.wikipedia.org/wiki/Light#Speed_of_light Photons travel through empty space at a speed of approximately 186,282 miles (299,792 kilometers) per second. http://whatis.techtarget.com/definition/0,,sid9_gci214455,00.html In a vacuum, empty space, all photons move at the nominal speed of light, c, defined as equal to 299,792,458 metres per second, or approximately 3×108 m s-1 http://en.wikipedia.org/wiki/Photon I would like to discuss the speed of photons only, since a stream of moving photons will leave a visible trace know as a beam of light or ray of light which will occupy different sets of distances at time t, which is confusing the issue I hope you understand this. I will have to go back to the initial experimental light speed experiments and come back to you... It has to do with dropping absolutaenity. (My Term) No standard web pages containing all your search terms were found. Your search - absolutaenity - did not match any documents. G
From: "N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox on 26 Apr 2005 00:30 Dear G: "G" <gehan(a)dialog.lk> wrote in message news:1114488546.951952.19870(a)l41g2000cwc.googlegroups.com... .... > What is the speed of light? It is established by convention to be 299792468 meters per second. It had been measured some 100 times since the late 1600s, and this is where it was set. The problem being that physical length standards suffer from a number of cumulatve effects, where time standards do not. So the meter is now established by c and time. David A. Smith
From: G on 26 Apr 2005 02:18 Henri We can consider the stars to be elements of a cosmic brownian motion (how is that for irony) I suspect that it will not balance to be absolute zero but be very very close Absolute reference? Yes I think so See Dr William's paper: God and Real Time William Lane Craig, halfway down where he quotes none other than P.C.W Davies http://www.leaderu.com/offices/billcraig/docs/realtime.html#text28 "At any given place in the universe, there is only one reference frame in which the universe expands isotropically. This privileged reference frame defines a privileged time scale (the time as told by a clock at rest in that frame). Two separated places have their privileged reference frames in mutual motion, because of the expansion of the universe. Nevertheless, the time measured by the entire collection of imaginary standard clocks are obviously correlated such that the global condition (e.g. average separation of two galaxies) of the universe appears the same at equal times as registered by every privileged clock (assuming they are all properly synchronized). Happily, the earth is moving very slowly relatively to the local privileged frame in our vicinity of the universe, so that Earth time is a fairly accurate measure of cosmic time.{28}" {28}P.C.W. Davies, "Space-Time Singularities in Cosmology and Black Hole Evaporations," in The Study of Time III, ed. J.T. Fraser, N. Lawrence, and D. Park (Berlin: Springer Verlag, 1978), p. 76. I have corrected spelling errors in the quotation. G
From: G on 26 Apr 2005 02:23 David So basically in laymans terms we can say the speed of light is s/t where s is the distance between source and target and t is the time between elapsed between switching on the light source and the illumination of the target? (all in the same frame) I thought the metre was defined in terms of wavelenght G
From: Henri Wilson on 26 Apr 2005 04:51
On 25 Apr 2005 23:18:30 -0700, "G" <gehan(a)dialog.lk> wrote: >Henri > > We can consider the stars to be elements of a cosmic brownian >motion (how is that for irony) I suspect that it will not balance to >be absolute zero >but be very very close If you take all the stars withing a sphere of certain radius, there must be a frame in which all momentum sums to zero. > >Absolute reference? Yes I think so No. The sphere in the above statement has no spatial reference. It is moving wrt other more distant similar spheres. > >See Dr William's paper: God and Real Time William Lane Craig, halfway >down >where he quotes none other than P.C.W Davies > >http://www.leaderu.com/offices/billcraig/docs/realtime.html#text28 > >"At any given place in the universe, there is only one reference frame >in which the universe expands isotropically. This privileged reference >frame defines a privileged time scale (the time as told by a clock at >rest in that frame). Two separated places have their privileged >reference frames in mutual motion, because of the expansion of the >universe. Nevertheless, the time measured by the entire collection of >imaginary standard clocks are obviously correlated such that the global >condition (e.g. average separation of two galaxies) of the universe >appears the same at equal times as registered by every privileged clock >(assuming they are all properly synchronized). Happily, the earth is >moving very slowly relatively to the local privileged frame in our >vicinity of the universe, so that Earth time is a fairly accurate >measure of cosmic time.{28}" > >{28}P.C.W. Davies, "Space-Time Singularities in Cosmology and Black >Hole Evaporations," in The Study of Time III, ed. J.T. Fraser, N. >Lawrence, and D. Park (Berlin: Springer Verlag, 1978), p. 76. I have >corrected spelling errors in the quotation. > > >G HW. www.users.bigpond.com/hewn/index.htm Sometimes I feel like a complete failure. The most useful thing I have ever done is prove Einstein wrong. |