Why is the (maximum) speed of light the number it is?

In summary: Maxwell's equations and is not sure if they fully answer the question as to why the speed of light is limited to 3x10^8ms^-1. He was referred to the electric and magnetic vacuum permittivities and Ampere's Law and is not sure where these relate. Maxwell's equations state that the speed of light is limited by the electric and magnetic vacuum permittivities. These two factors work together to keep the speed of light in a certain range.
  • #1
gracie
3
0
What limits the speed of light to 3x10^8ms^-1? I was referred to Maxwells equations and have studied them but am not sure if this is the full answer and am unsure where Maxwell's relate anyway, the lectures I watched were unclear apart from relating to Ampere's Law.

As much maths as possible to answer please :)
 
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  • #2
Physics cannot answer "why"-questions at a fundamental level. Light in vacuum has a fixed velocity. Its numerical value comes from our arbitrary definitions of the units meters and seconds.
It is possible to express the speed of light via the electric vacuum permittivity and magnetic vacuum permeability: c2 = 1/(ε0μ0)

It is possible to invent laws of physics where light has infinite speed. We just don't live in such a universe.
 
  • #3
Okay but in our universe, through whatever units we use, the speed of light is limited, right? But what is it limited by, and why is it that particular number, why not bigger or smaller?
 
  • #4
Also why can it be expressed with that equation? Where has that come from?
 
  • #5
gracie said:
But what is it limited by, and why is it that particular number, why not bigger or smaller?

again you are asking why type questions

That is just the speed it is
 
  • #6
Historically, we measured the speed of light through various ways. But in modern times we just define the speed of light as a certain value. Or more accurately, we define the meter as the distance traveled by light in vacuum in 1/299792458 second. If we chose a different definition for the meter, then the speed of light would have some different numerical value. So the number itself is arbitrary, invented by humans.

If you want to remove the arbitrariness from the question, you have to take some ratio (or more complicated expression) so the human units all cancel out. Then you get a dimensionless number. We don't have explanations for some dimensionless numbers we find in the universe, like the fine structure constant.
 

What is the maximum speed of light?

The maximum speed of light, also known as the speed of light in a vacuum, is approximately 299,792,458 meters per second. This value is denoted by the symbol 'c' in the famous equation E=mc^2.

Why is the speed of light considered to be the fastest possible speed?

According to Einstein's theory of relativity, the speed of light is the only constant in the universe. It is considered to be the fastest possible speed because as an object approaches the speed of light, its mass increases infinitely and it would require an infinite amount of energy to accelerate it further.

How was the speed of light first measured?

The speed of light was first accurately measured by Danish astronomer Ole Rømer in 1676 using the eclipses of Jupiter's moon Io. He observed that the time between eclipses varied as the distance between Earth and Jupiter changed due to their orbits around the sun.

Why is the speed of light in a vacuum different from the speed of light in other mediums?

The speed of light in a vacuum is a fundamental constant and is determined by the properties of space and time. In other mediums, such as air or water, the speed of light is slower because it is affected by the density and composition of the medium.

Can the speed of light be surpassed?

According to our current understanding of physics, it is not possible to surpass the speed of light. As an object approaches the speed of light, its mass increases and it would require an infinite amount of energy to accelerate it further. Additionally, the laws of physics as we know them break down at such extreme speeds.

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