Is the Speed of Light Changing? Implications for Permittivity and Permeability.

In summary, the speed of light can change when it goes from vacuum to media due to the change in permittivity and permeability. These properties are determined by the system of units, and in natural units they are all equal to 1. In CGS units, the vacuum permeability and permittivity do not exist. The fine structure constant, which characterizes the physics rather than the units, is experimentally measured and not yet derivable. Recent re-analysis of data from the Oklo reactor suggests a small decrease in the fine structure constant, which could translate into a small increase in the speed of light.
  • #1
iScience
466
5
If the speed of light is changing, does this mean that the permattivity and/or permeability are dynamically changing quantities? are these "constants" derivable yet or are they still only experimentally measured quantities?
 
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  • #2
iScience said:
If the speed of light is changing, does this mean that the permattivity and/or permeability are dynamically changing quantities? are these "constants" derivable yet or are they still only experimentally measured quantities?

What makes you think the speed of light (in vacuum) is changing?
 
  • #3
iScience said:
If the speed of light is changing, does this mean that the permattivity and/or permeability are dynamically changing quantities? are these "constants" derivable yet or are they still only experimentally measured quantities?
The speed of light, vacuum permettivity and vacuum permeability are all determined by the system of units. In natural units they are all equal to 1, and in CGS the vacuum permeability and permittivity do not even exist.

What you should really be asking is if the fine structure constant is derivable or only experimentally measured. That is a dimensionless number and so is independent of the system of units. It characterizes the physics rather than the units.

The answer is that the fine structure constant is experimentally measured, not yet derivable.
 
  • #4
Has there been a follow up to..

http://www.newscientist.com/article...t-may-have-changed-recently.html#.U6_HJ2cU91M

Now, Lamoreaux, along with LANL colleague Justin Torgerson, has re-analysed the Oklo data using what he says are more realistic figures for the energy spectrum of the neutrons present in the reactor. The results have surprised him. Alpha, it seems, has decreased by more than 4.5 parts in 108 since Oklo was live (Physical Review D, vol 69, p121701).

That translates into a very small increase in the speed of light (assuming no change in the other constants that alpha depends on), but Lamoreaux's new analysis is so precise that he can rule out the possibility of zero change in the speed of light. "It's pretty exciting," he says.
 
  • #5
What makes you think the speed of light (in vacuum) is changing?

I just assumed he was referring to vacuum

The speed of light, vacuum permettivity and vacuum permeability are all determined by the system of units. In natural units they are all equal to 1, and in CGS the vacuum permeability and permittivity do not even exist.

what's CGS?
 
  • #7
the speed of light will be changed when the light goes from the vacuum into the media due to the change of the permability and permittivity. the speed of the light is related to these material properties by checking the wave equations in the medias.
 

Related to Is the Speed of Light Changing? Implications for Permittivity and Permeability.

What is the speed of light?

The speed of light is a physical constant that represents the speed at which light travels in a vacuum. It is approximately 299,792,458 meters per second.

Can the speed of light be changed?

According to our current understanding of physics, the speed of light is a fundamental constant and cannot be changed. However, some theories suggest that the speed of light may have been different in the early universe.

Why is the speed of light considered the cosmic speed limit?

Einstein's theory of relativity states that the speed of light is the maximum speed at which all matter and information in the universe can travel. This is because as an object approaches the speed of light, its mass increases and requires an infinite amount of energy to accelerate further.

What would happen if the speed of light was changed?

If the speed of light were to change, it would have a profound impact on the laws of physics and the entire universe. It could potentially alter the behavior of particles, the structure of atoms, and the concept of time itself.

Are there any experiments or research being done to change the speed of light?

While there are ongoing studies and experiments to better understand the nature of light and its behavior, there is currently no known way to change the speed of light. Any changes to this fundamental constant would require a major breakthrough in our understanding of physics.

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