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Photon Speed
Name: Mike T.
Status: other
Age: 30s
Location: N/A
Country: N/A
Date: 2001-2002
Question:
How do emitted photons instantaneously travel at
the speed of light since they were not accelerated? At one instant
there is no photon, and at the next instant, it miraculously is already
travelling at the speed of light.
Replies:
Hi, Mike !!
A photon - as you know - is an electromagnetic (EM) wave .
Its energy is described by e = h. n in a quantum
of energy. All EM waves travel in the vacuum
with the speed of light. A photon is a form of energy and
results from transformations of another forms of energy.
When the photon appears it behaves like all EM waves.
It doest need to be accelerated. All bodies emit EM waves,
even a peace of ice. The question concerns more on the
frequency. If you see the light - visible light - it covers
a range of wave length between 400 and 700 nanometers.
When you mention in your question that "...emitted photons
instantaneously travel at speed of light and were not accelerated..."
than you are thinking like a particle behaviour that needs to be
accelerated, right ?? Than, we find ourselves at the hands of
the problem concerning to the dual behaviour particle-wave
of matter. You are thinking of particle and making a question
for waves...Waves do not need to be accelerated. Particles
do, but we are talking about wave-photons, arent we ??
And - besides of that - photons are generally regarded as
particles with zero mass and no electric charge...( again the
dual behaviour of matter ).
Alcir Grohmann
This is not an easy question and is not treated in introductory
spectroscopic texts or quantum mechanical texts, at least the ones I could
find. It involves time dependent quantum mechanics. The best treatment I
have been able to find so far is on the web site:
http://jchemed.chem.wisc.edu/JCEWWW/Articles/DynaPub/DynaPub.html
Vince Calder
Mike,
Newton's laws of physics do not apply to objects moving near the speed of
light, or to objects smaller than an atom. Small scale requires quantum
physics. Large speed requires relativity. Light fits both criteria. Also,
light photons have zero mass. This is another fact that makes them unusual.
At the level of quantum physics, things change form at almost random times.
You cannot predict where something will be. You can only say it has a
probability of being somewhere. Objects under the right conditions can
change into other objects without being forced to. A photon flying through
space can change into an electron and anti-electron, or vice-versa.
Quantities such as total momentum, total energy, and total electric charge
must be conserved, but many things can change. We do not know how or why it
happens.
We can deal with a bundle of millions of particles, working with average
effects (a baseball is millions of protons, neutrons, and electrons; a beam
of light is millions of photons). We do not know how an individual particle
works. We do not know what actually happens during the process of changing,
only before and after. We don't know whether it requires any time at all.
It is almost like a change of reality, switching between a universe with a
photon and a universe with an electron and anti-electron.
Dr. Ken Mellendorf
Illinois Central College
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Update: June 2012
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