Speed of light
The speed of light in a vacuum (postulated to be constant for all inertial observers by the special theory of relativity) is exactly 299,792,458 meters per second (approximately 186,282.3 miles per second). As the speed of light is now used to define the SI meter, this is now the value by definition.
In physics, it is often represented in equations by the letter c, as in
- λ = c / f
(wavelength of an electromagnetic wave in vacuum = the speed of light divided by the wave's frequency).
The speed of light is about one foot per nanosecond. The late computer pioneer Admiral Grace Hopper was fond of keeping foot-long lengths of wire in her purse; she used them as props for her talks, referring to them as "nanoseconds," and using them to explain how the speed of light set limitations on computing systems (Although the rate of energy propagation in copper wire is significently lower than the speed of light).[1]
The speed of light is slower in any medium which is not a vacuum, and varies from medium to medium. This variation gives rise to (as a result of quantum mechanics, particularly the concept of a path of least action) the phenomenon of refraction. When a charged particle exceeds the speed of light in the medium in which it is travelling, it emits Cherenkov Radiation.
Since the speed of light in a vacuum is observed to be constant, it can be used to define distances as well. The distance that light travels in one year is known as a light-year, which is about 6 million million (6x1012) miles.
Starlight Problem For the Big Bang Theory
The starlight problem is an argument against the Big Bang Theory which theorizes a universe of billions of years old. [2] The creation science organization Answers in Genesis has stated the following regarding the starlight problem for the Big Bang Theory and the work of Charles W. Misner is cited who published his work in Physical Review Letters:
| â | The problem is this: even assuming the big bang timescale, there has not been enough time for light to travel between widely separated regions of space. So, how can the different regions of the current [cosmic microwave background] CMB have such precisely uniform temperatures if they have never communicated with each other? This is a light-travelâtime problem.[3] | â |
The speed of light raises several minor questions for Young Earth Creationists including that of the starlight problem.
Notes and references
- â Chiarella, Donald Joseph Gray (2002), Life in God's Management Corps, p. 14
- â http://www.answersingenesis.org/creation/v25/i4/lighttravel.asp
- â http://www.answersingenesis.org/creation/v25/i4/lighttravel.asp