There was a good Horizon (i think) programme the other day looking at the Italian experiment that found some particles may travel faster than light by going into 'the bulk' outwith our universes membrane and reappearing in a spot that it could not have reached in the time it took had it remained within.
There was a good Horizon (i think) programme the other day looking at the Italian experiment that found some particles may travel faster than light by going into 'the bulk' outwith our universes membrane and reappearing in a spot that it could not have reached in the time it took had it remained within.
The neutrino experimental results were flawed, as most people thought they would be. Quite why the BBC re-broadcast that programme without updating it is a mystery. So all the theoretical waffle to "explain" the result turned out to be unnecessary, because there was no result to explain.
I'm also wondering that. I can see how they measured the speed since the technology became available, but I doubt they'll know for a fact what the speed was before they had the technology to measure it. I'm not so sure about the human race being around for only 3,000 years. I'd say they've been around for quite a bit longer than that.
I did say the human race had been around for a few thousand, not 3. Actually it's around 200,000 years.
The speed of light, however was measured for the first time in 1675.
The measurement has changed over that time also.
History of measurements of c (in km/s)
1675 Rømer and Huygens, moons of Jupiter 220000
1729 James Bradley, aberration of light 301000
1849 Hippolyte Fizeau, toothed wheel 315000
1862 Léon Foucault, rotating mirror 298000±500
1907 Rosa and Dorsey, EM constants 299710±30
1926 Albert A. Michelson, rotating mirror 299796±4
1950 Essen and Gordon-Smith, cavity resonator299792.5±3.0
1958 K.D. Froome, radio interferometry 299792.50±0.10
1972 Evenson et al., laser interferometry 299792.4562±0.0011
1983 17th CGPM, definition of the metre 299792.458 (exact)
It's only been measured, with any accuracy, at it's current value for around 100 years and I mentioned a possible (pure finger in the air) value for deceleration of 0.001% over 1000 years.
So over 100 years that would be 0.0001% of 299,792,458 m/s which would have been around 300 m/s. Just over 150 years ago the accuracy was within +/- 500 m/s.
This is just pure conjecture from the fact that we've only been measuring it for less than 400 years and, of those, only 150 of them with meaningful accuracy.
The neutrino experimental results were flawed, as most people thought they would be. Quite why the BBC re-broadcast that programme without updating it is a mystery. So all the theoretical waffle to "explain" the result turned out to be unnecessary, because there was no result to explain.
The explanations were still interesting and valid reasoning that may yet need testing at some point in the future to explain the universe that we have not yet nailed down as understanding.
I did say the human race had been around for a few thousand, not 3. Actually it's around 200,000 years.
The speed of light, however was measured for the first time in 1675.
The measurement has changed over that time also.
Yes, because our ability to measure it has improved, not because the speed of light has changed. Or do you think it speeded up, then slowed down, and then got a bit faster before settling on its present value?
It's only been measured, with any accuracy, at it's current value for around 100 years and I mentioned a possible (pure finger in the air) value for deceleration of 0.001% over 1000 years.
So over 100 years that would be 0.0001% of 299,792,458 m/s which would have been around 300 m/s. Just over 150 years ago the accuracy was within +/- 500 m/s
And as I told you, that would be easily detectable in modern measurements. Even in 1972, the uncertainty was only +/- 1.1 m/s - and most of that was down to the uncertainty in the definition of the metre. Indeed, since the metre is now defined as the distance travelled by light in 1/299,792,458 of a second, improvements in the measured speed of light simply affect how long a metre is.
The explanations were still interesting and valid reasoning that may yet need testing at some point in the future to explain the universe that we have not yet nailed down as understanding.
They can hardly have been "valid reasoning" if they explained something which did not in fact happen.
A number of papers were produced purporting to explain the (assumed correct) results in terms of new physics, and a number of papers were produced purporting to identify some fatal flaw in the experimental procedure that made the results incorrect. And as far as I know, every single one of them was wrong.
Anyway, as I've said we've only been measuring the speed of light for 400 out of 3,800,000,000(+) years and we can only theorise that it has always been constant, which it probably has.
Late night BBC radio 5 with dr Carl, on wed night last week also stated that the early universe went through a burst of expansion which exceeded the speed of light. Note this was a burst of expansion, before and after expansion was slower.
Tut I wish science had come up with a different word for the model to explain a natural phenomenen... the 'theory' word is causing no end of problems
indeed, it is a huge problem with the unscientific layman.
i usually find if someone doesn't understand the word, then its highly unlikely they do not understand the science and as such it is not worth wasting time on.
The speed of light, one of the most sacrosanct of the universal physical constants, may have been lower as recently as two billion years ago - and not in some far corner of the universe, but right here on Earth.
The controversial finding is turning up the heat on an already simmering debate, especially since it is based on re-analysis of old data that has long been used to argue for exactly the opposite: the constancy of the speed of light and other constants.
A varying speed of light contradicts Einstein's theory of relativity, and would undermine much of traditional physics. But some physicists believe it would elegantly explain puzzling cosmological phenomena such as the nearly uniform temperature of the universe. It might also support string theories that predict extra spatial dimensions.
The threat to the idea of an invariable speed of light comes from measurements of another parameter called the fine structure constant, or alpha, which dictates the strength of the electromagnetic force. The speed of light is inversely proportional to alpha, and though alpha also depends on two other constants (see graphic), many physicists tend to interpret a change in alpha as a change in the speed of light. It is a valid simplification, says Victor Flambaum of the University of New South Wales in Sydney.
...
Surely the variability of the speed of light wouldn't contradict Einstein as long as, even with new values, the invariability to the observer, and the integrity of e=mc2, remained?
the constancy of lightspeed is a necessary consequence of maxwell's electrodynamcs. the same theory that predicted radio waves also says lightspeed must be constant.
all modern physics is built on this. and it seems very successul since we can build computers and digital tellys and phones and stuff. so if the theory turned out to be wrong, it would be a very big surprise .
Late night BBC radio 5 with dr Carl, on wed night last week also stated that the early universe went through a burst of expansion which exceeded the speed of light. Note this was a burst of expansion, before and after expansion was slower.
You need to be careful here. There is no problem with a metric expansion - an expansion of space itself - exceeding the speed of light, within the framework of mainstream physics. Indeed, that's what "cosmological inflation" requires - and that is the theory to which the research in the OP is seeking an alternative.
In addition, very distant galaxies are known to be receding faster than the speed of light, because the Hubble expansion rate depends on distance. This too is not contrary to relativity, does not require a variable speed of light, and is mainstream physics.
the constancy of lightspeed is a necessary consequence of maxwell's electrodynamcs. the same theory that predicted radio waves also says lightspeed must be constant.
all modern physics is built on this. and it seems very successul since we can build computers and digital tellys and phones and stuff. so if the theory turned out to be wrong, it would be a very big surprise .
James Franson from Maryland University has done some observational research indicating light may have slowed down even in the interstellar vacuum.
They can hardly have been "valid reasoning" if they explained something which did not in fact happen.
A number of papers were produced purporting to explain the (assumed correct) results in terms of new physics, and a number of papers were produced purporting to identify some fatal flaw in the experimental procedure that made the results incorrect. And as far as I know, every single one of them was wrong.
Theories with large extra dimensions may be tested using sterile neutrinos living in the bulk. A bulk neutrino can mix with a ?a- vor neutrino localized in the brane leading to unconventional patterns of neutrino oscillations. A resonance phenomenon, strong mixing be- tween the ?avor and the sterile neutrino, allows to determine the radius of the large extra dimension. If our brane is curved, then the sterile neutrino can take a shortcut through the bulk, leading to an appar- ent superluminal neutrino speed.
Published somewhat before the italian experiment. In fact the paper prompts the experiment.
Most likely bollocks. An old paper that was knocking around unremarked for several years until he finally managed to get it into a journal, and then some useless newspaper hack got hold of it and thought another "Einstein wrong" story would make good copy. And suddenly a not very interesting piece of speculation becomes headline news around the world. The most likely explanation for the neutrinos arriving earlier is that they were created earlier, or came from somewhere other than SN 1987A .
This seems to be in line with research indicating that lightseed may not be constant due to fluctuations in quantum vacuum.
Needless to say, it has nothing to do with that.
Haven't you got a really straightforward electrical engineering question you ought to be answering in another thread?
constant lightspeed is only a postulate in special relativity, but it is a PREDICTION of electrodynamics. thus, if lightspeed varies, all physics since 1860 is proved false. which seems rather unlikely .......
Published somewhat before the italian experiment. In fact the paper prompts the experiment.
I don't think it did. I thought the OPERA experiment was investigating neutrino oscillations, and that the apparent superluminal neutrino velocity (subsequently found to be due to a fault in the equipment) was an entirely unexpected finding.
Edit: That paper was submitted in 2011. OPERA was built between 2003 and 2008.
I did say the human race had been around for a few thousand, not 3. Actually it's around 200,000 years.
The speed of light, however was measured for the first time in 1675.
The measurement has changed over that time also.
History of measurements of c (in km/s)
1675 Rømer and Huygens, moons of Jupiter 220000
1729 James Bradley, aberration of light 301000
1849 Hippolyte Fizeau, toothed wheel 315000
1862 Léon Foucault, rotating mirror 298000±500
1907 Rosa and Dorsey, EM constants 299710±30
1926 Albert A. Michelson, rotating mirror 299796±4
1950 Essen and Gordon-Smith, cavity resonator299792.5±3.0
1958 K.D. Froome, radio interferometry 299792.50±0.10
1972 Evenson et al., laser interferometry 299792.4562±0.0011
1983 17th CGPM, definition of the metre 299792.458 (exact)
It's only been measured, with any accuracy, at it's current value for around 100 years and I mentioned a possible (pure finger in the air) value for deceleration of 0.001% over 1000 years.
So over 100 years that would be 0.0001% of 299,792,458 m/s which would have been around 300 m/s. Just over 150 years ago the accuracy was within +/- 500 m/s.
This is just pure conjecture from the fact that we've only been measuring it for less than 400 years and, of those, only 150 of them with meaningful accuracy.
I don't think it did. I thought the OPERA experiment was investigating neutrino oscillations, and that the apparent superluminal neutrino velocity (subsequently found to be due to a fault in the equipment) was an entirely unexpected finding.
Edit: That paper was submitted in 2011. OPERA was built between 2003 and 2008.
Still, the theory was proposed prior to the Italian findings.
... and until more recently none of them would have been able to produce an efficient enough vacuum to accurately measure the speed of light (in a vacuum) either.
However if parts of space were not a perfect vacuum then the speed of light would be affected, however slightly, by the refractive index of the medium it was travelling through.
Comments
I did say the human race had been around for a few thousand, not 3. Actually it's around 200,000 years.
The speed of light, however was measured for the first time in 1675.
The measurement has changed over that time also.
It's only been measured, with any accuracy, at it's current value for around 100 years and I mentioned a possible (pure finger in the air) value for deceleration of 0.001% over 1000 years.
So over 100 years that would be 0.0001% of 299,792,458 m/s which would have been around 300 m/s. Just over 150 years ago the accuracy was within +/- 500 m/s.
This is just pure conjecture from the fact that we've only been measuring it for less than 400 years and, of those, only 150 of them with meaningful accuracy.
What's 400 years compared to a period in excess of 13,000,000,000 years.
I also assume a linear deceleration, what if it had been an exponential one tending towards a final value rather like a radioactive half-life?
... or like a damped oscillation where the speed of light actually oscillated somewhere around it's current value as a central point?
And as I told you, that would be easily detectable in modern measurements. Even in 1972, the uncertainty was only +/- 1.1 m/s - and most of that was down to the uncertainty in the definition of the metre. Indeed, since the metre is now defined as the distance travelled by light in 1/299,792,458 of a second, improvements in the measured speed of light simply affect how long a metre is.
With no apparent point.
A number of papers were produced purporting to explain the (assumed correct) results in terms of new physics, and a number of papers were produced purporting to identify some fatal flaw in the experimental procedure that made the results incorrect. And as far as I know, every single one of them was wrong.
This is an Internet forum, who needs points.
Anyway, as I've said we've only been measuring the speed of light for 400 out of 3,800,000,000(+) years and we can only theorise that it has always been constant, which it probably has.
indeed, it is a huge problem with the unscientific layman.
i usually find if someone doesn't understand the word, then its highly unlikely they do not understand the science and as such it is not worth wasting time on.
all modern physics is built on this. and it seems very successul since we can build computers and digital tellys and phones and stuff. so if the theory turned out to be wrong, it would be a very big surprise .
In addition, very distant galaxies are known to be receding faster than the speed of light, because the Hubble expansion rate depends on distance. This too is not contrary to relativity, does not require a variable speed of light, and is mainstream physics.
James Franson from Maryland University has done some observational research indicating light may have slowed down even in the interstellar vacuum.
http://www.dailymail.co.uk/sciencetech/article-2672092/Was-Einstein-wrong-Controversial-theory-suggests-speed-light-SLOWER-thought.html
This seems to be in line with research indicating that lightseed may not be constant due to fluctuations in quantum vacuum.
http://arxiv.org/abs/1109.6354
Theories with large extra dimensions may be tested using sterile neutrinos living in the bulk. A bulk neutrino can mix with a ?a- vor neutrino localized in the brane leading to unconventional patterns of neutrino oscillations. A resonance phenomenon, strong mixing be- tween the ?avor and the sterile neutrino, allows to determine the radius of the large extra dimension. If our brane is curved, then the sterile neutrino can take a shortcut through the bulk, leading to an appar- ent superluminal neutrino speed.
Published somewhat before the italian experiment. In fact the paper prompts the experiment.
Needless to say, it has nothing to do with that.
Haven't you got a really straightforward electrical engineering question you ought to be answering in another thread?
Edit: That paper was submitted in 2011. OPERA was built between 2003 and 2008.
Early humans were around 7 million years ago. Homo Sapiens, modern humans, were in Africa about 200,000 years ago.
Still, the theory was proposed prior to the Italian findings.
However if parts of space were not a perfect vacuum then the speed of light would be affected, however slightly, by the refractive index of the medium it was travelling through.
Neither would early Homo Sapiens.