Expert: Philip A. Stahl - 6/21/2011

Question
QUESTION: 1]Can the speed of light be increased? 2]Is it possible for light to  move objects?

ANSWER: Answers:

1) No, the speed of light can't be increased.

But, an addendum and proviso. In a paper appearing in the journal Nature, in July 2000, physicists at the NEC Research Institute in Princeton, New Jersey claimed to have "broken the limit set by the speed of light". They achieved this by firing a laser pulse into a glass chamber filled with a cesium (Cs) atom vapor.

NEC’s Lijun Wang, in fact, insisted he’d created an experiment in which light speed was not merely exceeded by an added increment, but by a factor of three hundred!  This meant that an almost identical light pulse exited the chamber and traveled about sixty feet before the main part of the laser pulse finished entering the chamber, Wang said.

Needless to say, this flouts well-known accepted precepts of causality. (Wherein causes are assumed to precede effects).  The problem here is that the experiment hasn't been confirmed to the best of my knowledge, so we take it with more or less a grain of salt. (Ok, maybe a tad more!)

2) While light does possess inertia (a minimal mass) it isn't enough to move an extended object of significant mass, all the sci fi "force beams" to the contrary.

Hope this helps!

---------- FOLLOW-UP ----------

QUESTION: 1]I also want to know why light can move so fast. 2]That and what category light can be place in,like is it a gas,plasma,etc.

ANSWER: Hello,

No one knows 'why' light moves 'so fast', but that is also because in science we give more emphasis to HOW questions, as opposed to 'Why?'  Light is simply one band of the total electro-magnetic (EM)spectrum, each constituent of which travels at the speed of about 300,000 km/s.

The particular speed was predicted from James Clerk Maxwell's EM wave equations. One factor in the standard wave equation comes off as:

1/c^2 = u(o) e(o)

where u(o) = 4 pi x 10^-7 H/m

or the magnetic permeability of free space,

and: e(o) = 8.85 x 10^-12 F/m

or the electrical permittivity of free space.


If one then solves for c (the speed) one obtains:

c = 1/ [u(o) e(o)]^1/2

= 1/ {[4 pi x 10^-7 H/m] x [8.85 x 10^-12 F/m]}^1/2

= 2.99999 x 10^8 m/s

Which is how the velocity of light was forecast before even measured.

Why? I guess one answer would be:  Because James Clerk Maxwell's equations say so!

Light is not a plasma, and certainly not a gas.

It is under the general header (as noted above) of "electromagnetic radiation" so the category would likely be "radiation".






---------- FOLLOW-UP ----------

QUESTION: What is electromagnetic radiation and can you give me some examples,other than light?

Answer
Hello,

This site is rich in information, more than I could ever give at one time, and also full of excellent visuals- graphics- diagrams.

http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html

It shows multiple examples, also where each fall in the EM spectrum. It also gives practical examples of each in every day life, e.g. the doctor using x-rays to look at bones, etc.

An excellent, educational site overall.