From the Internet: The answer to your first question is yes, for all intents and purposes,
photons traveling through intergalactic space could, and in fact do, lose energy due to the expansion of spacetime in the Universe
. As the photons lose energy their wavelengths become longer.
Does light energy dissipate in space?
In empty space, the wave does not dissipate
(grow smaller) no matter how far it travels, because the wave is not interacting with anything else. This is why light from distant stars can travel through space for billions of light-years and still reach us on earth.
How can the photons from the laser somehow lose energy while still traveling at the speed of light?
Actually, however, there is one way that photons do lose energy as they travel through space.
Because the universe is expanding, the photon’s wavelength increases very slightly over time
, and in so doing loses a bit of energy.
What happens when photons lose energy?
What happens to the energy lost by photons as they become red-shifted by gravity or cosmic expansion? A photon’s energy is inversely proportional to it’s wavelength.
As it becomes red-shifted, it’s wavelength becomes larger so it’s energy becomes smaller
.
How do photons travel through space?
Does redshifted light lose energy?
Photons do not lose energy due to a redshift
. It is just that photons produced after the shift began have less energy than photons produced before the Doppler shift began. If the source is receding then those photons all have lower energy than photons would have if the Doppler motion stopped.
Does light have infinite energy?
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The energy required to accelerate a massive particle to the speed of light is infinite, yes
.
Why does light become weaker with distance?
Notice that as the distance increases, the light must spread out over a larger surface and the surface brightness decreases in accordance with a “one over r squared” relationship. The decrease goes as r squared because
the area over which the light is spread is proportional to the distance squared
.
Do photons follow Geodesics?
The most commonly accepted view is that gravity bends spacetime, and the curvature itself is the deformation of spacetime itself.
All known particles (not just photons) follow this geodesic.
Do photons dissipate?
Light is made up of particles called photons that travel like waves. Unless they interact with other particles (objects), there is nothing to stop them. Unlike some types of particles,
they do not decay
, meaning that they do not spontaneously turn into other types of particles.
Do photons last forever?
Now, by studying ancient light radiated shortly after the big bang, a physicist has calculated the minimum lifetime of photons, showing that
they must live for at least one billion billion years, if not forever
.
Where does a photon get its energy?
Since photons (particles of light) have no mass, they must obey E = pc and therefore get all of their energy
from their momentum
.
Why do photons not experience time?
Yet despite this incredible journey, the photon itself experiences none of what we know as time:
it simply is emitted and then instantaneously is absorbed, experiencing the entirety of its travels through space in literally no time
. Given everything that we know, a photon never ages in any way at all.
Do photons always travel at the speed of light?
A photon of light does not accelerate to light speed. Rather, a photon is already traveling at light speed c when it is created. It’s not like a photon jumps from a speed of zero to light speed instantaneously. Rather,
a photon is always traveling at c, from the moment of its creation
.
Do photons experience time dilation?
Photons do not experience time
. [SNARK: Are you worried they might get bored?] Just think about that idea. From the perspective of a photon, there is no such thing as time.
How are photons destroyed?
Photons are easily created and destroyed.
An electron moving in a strong magnetic field will generate photons just from its acceleration. Similarly,
when a photon of the right wavelength strikes an atom, it disappears and imparts all its energy to kicking the electron into a new energy level
.
Why do photons red shift?
In the widely accepted cosmological model based on general relativity, redshift is
mainly a result of the expansion of space
: this means that the farther away a galaxy is from us, the more the space has expanded in the time since the light left that galaxy, so the more the light has been stretched, the more redshifted …
Where does the energy of a redshifted photon go?
The short answer, though, is that light loses energy as the Universe expands, and that energy goes
into the expansion of the Universe itself
, in the form of work.
Does light have gravity?
Light has energy, energy is equivalent to mass, and mass exerts gravitational force. Thus,
light creates gravity
, i.e. the bending of space-time. As for how much gravity, it would depend on how much energy.
How do we know photons have no mass?
Why do photons have no mass? In short,
the special theory of relativity predicts that photons do not have mass simply because they travel at the speed of light
. This is also backed up by the theory of quantum electrodynamics, which predicts that photons cannot have mass as a result of U(1) -gauge symmetry.
Does E mc2 apply to photons?
So a photon with constant mass when traveling at the speed of light, that is all photons normally experienced, cannot be validly said to obey Einstein’s E = mc^2 or the associated energy-momentum theorem.
Einstein’s E = mc^2 does not apply to any particle that travels at the speed of light
.
Why is speed of light not infinite?
That something, the universal conversion factor, is the speed of light. The reason that it is limited is simply the fact that
a finite amount of space is equivalent to a finite amount of time
.
Do ocean waves lose energy as they travel?
As the waves propagate away,
most of that energy tends to be conserved
, and swells can travel enormous distances without much loss of energy.
Can light travel through liquids?
Visible light can also travel through certain types of glass, plastics, water, and other materials
. Because of the physical differences in the makeup of the materials light actually travels slower through water and glass.
