Post by: Alan McDougall on 27/05/2016 19:44:22
There for instance has been some speculation in the scientific community, that c might have differed in the distant past?
Any Comments
Alan
Post by: chris on 28/05/2016 10:16:28
Post by: Alan McDougall on 28/05/2016 10:58:54
The speed if light, c, is a constant in a constant medium. But the speed will change when light moves from one medium into another, such as transitioning between air and glass, which is the basis of refraction.
I know this Chris, in the laboratory they have slowed down c to a snails pace.
There is some speculation in the scientific community that for instance c might have differed slightly during the early evolution of the universe?
I will seek citation and return?
Here is one example go to link below?
http://www.livescience.com/29111-speed-of-light-not-constant.html
Post by: puppypower on 28/05/2016 12:40:09
Although this net direction of potential is well documented, the traditions define the earth as the ground state. This began in ancient times and is still allowable because of the concept of relative reference, which states there is no preferred reference. The conceptual problem with this is, if you defined a potentiated reference, as the ground state, there will hidden potentials. It can work, but it becomes more abstract as new sources of hidden potential appear and need to be attached.
As an analogy, sea level on the earth, is the ground state for the all water in the atmosphere as well as on the surface of the earth. Sea level will be the same in all these references; clouds, mountains, lakes, rivers and streams, etc. Sea level is the ground state where water stops seeking a lower level. Photons never "net" slow down, speed up or become a different particle, since they are already at C-level.
Although sea level makes things much easier, since this is the same for all water elevation references, one can also choose lake earth as the ground state. The conceptual problem is lake earth, even if static, contains potential relative to the true ground state; sea level.
If given the option, the water in the lake will continue to flow, since it contains potential relative to sea level. If the lake appears all dammed up, we may not see this, right away. But forces and entropy will continue to act trying to turn static into dynamics so the potential can lower. One may argue the virtual particles we see in the lab is nothing but the lake leaking, trying to get back to C. Virtual particles go from energy to matter, where stye may interact, and then back to energy. This tells me, virtual particles may be connected to an activation energy process; helps change static into dynamic for flow back to C-level. This may well a source of energy we can tap into for the future. It will not make sense, if we assume lake earth is the ground state. Then it will not seem directed, but random.
Getting back to the whether the speed of light is constant; Sea level is dependent on many factors. For one thing, it is dependent on how much liquid water is in play. For example, if we froze all the water on the earth, as ice at the poles; huge mountains of ice, sea level will be at bottom of the current ocean basins. One could conceptually change C-level, based on how the water is in play; phases of matter.
Ice does not move toward sea level in the same way as liquid water does. If we have a pipe full of water that connects the lake to the sea level, there is a driving force. If we freeze the water in the lake, the potential is the same, but it is locked into place. But in the example above, where al the water is as mountains of ice at the poles, sea level becomes the bottom of the ocean. This add more potential to the ice, to increase the odds it can flow.
Our current universe is in a dynamic equilibrium, where potential is decreasing; water flows (forces act), allowing C-level to stay constant. But their may have been a time; ice age of the universe, where a much deeper sea level was in play to get the ice ball rolling. For example, if we assume a BB singularity, this is not much different from the mother of all black holes. The potential is locked int place like a mountain of ice. We may need to deepen C-level for the needed inflation. Once the dam breaks and the oceans are full, C level normalizes.
Post by: evan_au on 29/05/2016 11:44:40
Quote from: Alan McDougall
Are the fundamental constants of nature really constant?All engineers know that all constants are variable - if you try measuring them under enough different conditions...
Quote
c might have differed in the distant past?There is a table here of historical estimates of c. It jumps around a bit, without showing a definite trend - but that is what you would expect from successive attempts to perform a difficult measurement.
https://en.wikipedia.org/wiki/Speed_of_light#History
Another factor is at work - if your new result is too different from previous measurements, you will think something is wrong, and try and fix it. However, if the uncertainties overlap with the previous best measurement, you will think it is OK, and won't try to fix it. That can lead to an apparent trend when comparing measurements in a short period of time.
Anyway, now the definition of the second and the meter are derived from the same source (Cesium atoms), so the speed of light in meters per second is defined as an exact value.
To obtain an estimate of c looking back before the first successful human measurements, I guess you could try looking at the flash of a supernova, bouncing off the shells of dust shed by the star when it was in its red giant phase. We can measure the diameter of the dust clouds using a telescope, and we can time the delay since the original supernova (arriving on a direct line-of-sight).
Post by: JohnDuffield on 30/05/2016 15:17:07
Are the fundamental constants of nature really constant?No. That's a popscience myth perpetrated by the sort of people who peddle the Goldilocks multiverse. The fine-structure constant α = e²/4πε0hc isn't constant, see NIST (http://physics.nist.gov/cuu/Constants/alpha.html): "Thus α depends upon the energy at which it is measured, increasing with increasing energy, and is considered an effective or running coupling constant". It's a running constant, which means it isn't constant. The speed of light isn't constant either:
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi.stack.imgur.com%2F8KXbI.jpg&hash=412e9becd778557cb37b075314c6a05c)
There for instance has been some speculation in the scientific community, that c might have differed in the distant past? Any Comments?I think it did, but whilst Magueijo and others speculate that the speed of light was faster in the early universe, I think they got it back to front, and it was slower. The speed of light is lower where energy density is higher. See this Wikipedia article (https://en.wikipedia.org/wiki/Variable_speed_of_light), but note that it's incorrect where it refers to Einstein.
Post by: jeffreyH on 30/05/2016 17:39:04
Are the fundamental constants of nature really constant?No. That's a popscience myth perpetrated by the sort of people who peddle the Goldilocks multiverse. The fine-structure constant α = e²/4πε0ħc isn't constant, see NIST (http://physics.nist.gov/cuu/Constants/alpha.html): "Thus α depends upon the energy at which it is measured, increasing with increasing energy, and is considered an effective or running coupling constant". It's a running constant, which means it isn't constant. The speed of light isn't constant either:
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi.stack.imgur.com%2F8KXbI.jpg&hash=412e9becd778557cb37b075314c6a05c)There for instance has been some speculation in the scientific community, that c might have differed in the distant past? Any Comments?I think it did, but whilst Magueijo and others speculate that the speed of light was faster in the early universe, I think they got it back to front, and it was slower. The speed of light is lower where energy density is higher. See this Wikipedia article (https://en.wikipedia.org/wiki/Variable_speed_of_light), but note that it's incorrect where it refers to Einstein.
Why do you always spout such nonsense? It would be good to understand your motivation. Of course in your world no one need worry about observational evidence. That is one thing that is certainly apparent.
Post by: JohnDuffield on 30/05/2016 18:06:23
I say these things to counter the popscience nonsense that flatly contradicts what Einstein said, and the hard scientific evidence of things the Shapiro delay:
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fi.stack.imgur.com%2FIlSrh.jpg&hash=1613bec4ee18c7dafb26d2447d986a69)
Note the bit that says this: "Because, according to the general theory, the speed of a light wave depends on the gravitational potential along its path".
Post by: jeffreyH on 30/05/2016 18:40:56
is also a derivation of the fine structure constant. Here k_e is the Coulomb constant, e is the elementary charge, hbar is the reduced Planck constant and c of course is the speed of light. So John which of these do you suggest should be variable?
Post by: Alan McDougall on 30/05/2016 23:30:11
Well
It is true that if the fundamental constants differed even minutely, we would have not come into existence because our universe would have been , hostile to life?
Post by: JohnDuffield on 31/05/2016 08:04:56
WellWriting alpha as
, I'd say elementary charge e is not variable because of conservation of charge. But I'd say ε0 is variable along with c, because c = √(1/ε0μ0). Some people say h is variable, see this physicsworld article (http://physicsworld.com/cws/article/news/2010/sep/02/changes-spotted-in-fundamental-constant), but I'm not sure about that. Quote from: Alan McDougall
It is true that if the fundamental constants differed even minutely, we would have not come into existence because our universe would have been , hostile to life?That's what the multiverse guys say Alan, but IMHO it's misinformation used to promote a non-scientific idea.
Post by: evan_au on 31/05/2016 10:51:53
Quote from: Alan McDougall
because our universe would have been , hostile to life?
I agree that if fusion never produced elements past Helium that the universe would have been hostile to protein-based creatures like us.
But in a hypothetical like this, it's a bit broad-brush to say that the universe would be hostile to all forms of life (including ones quite unlike us).
Post by: jeffreyH on 31/05/2016 13:30:09
WellWriting alpha asQuote from: Alan McDougallIt is true that if the fundamental constants differed even minutely, we would have not come into existence because our universe would have been , hostile to life?That's what the multiverse guys say Alan, but IMHO it's misinformation used to promote a non-scientific idea.
What has a multiverse got to do with fundamental constants? Have you finally lost it completely?
Post by: JohnDuffield on 31/05/2016 14:07:29
"The Multiverse hypothesis proposes the existence of many universes with different physical constants, some of which are hospitable to intelligent life (see multiverse: anthropic principle). Because we are intelligent beings, we are, by definition, in a hospitable universe. This idea has led to considerable research into the anthropic principle and has been of particular interest to particle physicists, because theories of everything do apparently generate large numbers of universes in which the physical constants vary widely. As yet, there is no evidence for the existence of a multiverse, but some versions of the theory do make predictions that some researchers studying M-theory and gravity leaks hope to see some evidence of soon.[31] Some multiverse theories are not falsifiable, thus scientists may be reluctant to call any multiverse theory 'scientific'...."
I think multiverse theories are not 'scientific'. Particularly since physical constants vary in this universe.
Post by: Alan McDougall on 31/05/2016 15:11:18
See Wikipedia (https://en.wikipedia.org/wiki/Fine-tuned_Universe#Multiverse) :
"The Multiverse hypothesis proposes the existence of many universes with different physical constants, some of which are hospitable to intelligent life (see multiverse: anthropic principle). Because we are intelligent beings, we are, by definition, in a hospitable universe. This idea has led to considerable research into the anthropic principle and has been of particular interest to particle physicists, because theories of everything do apparently generate large numbers of universes in which the physical constants vary widely. As yet, there is no evidence for the existence of a multiverse, but some versions of the theory do make predictions that some researchers studying M-theory and gravity leaks hope to see some evidence of soon.[31] Some multiverse theories are not falsifiable, thus scientists may be reluctant to call any multiverse theory 'scientific'...."
I think multiverse theories are not 'scientific'. Particularly since physical constants vary in this universe.
I agree with you the multiverse is just at best speculation, without an iota of proof.