Discussion Forum

HOW DOES LIGHT TRAVEL IN SPACE?

Q1)As far as i know light require some medium so, how does light travel through space as there is no medium in space ?
Q2)How does light(photon/ light quanta) particles make us see objects or u can take it as how does is shines or give light?
i know it its property its a fact i know but but why & how does it give light in specific.

• poornakumar b says:

EM radiation (light is part of it) needs a medium (Ether) or not was settled long ago (almost a century) by ‘Michelson-Morley’ experiment that couldn’t prove its (Ether’s) existence. Einstein took off from this failure and proposed that in the direction of motion the ‘body’ (on which the ‘set-up’ rests) actually shrank (FitzGerald Contraction) on account of, in proportion to the speed. That is how the Relativity theory began. Light can travel in vacuuo and at a constant speed.
In response to your other query ‘How does light travel’ it travels in straight line unless a massive body (a star) is nearby. In that case it deviates towards that body the angle (at a constant speed) being proportional to its mass. If the body is adequately (too) massive, light ends up in (on) that body. As no light issues forth from it, the body appears ‘black’ (=no light) and is promptly termed ‘Black Body’.
Q2) : It invites a discussion of interaction of ‘light’ with matter. Light being Electro-magnetic in nature has Electric field oscillations and Magnetic field oscillations in planes mutually perpendicular and both transverse (perpendicular again) to the direction of propagation, as per Poynting’s theorem.
It all depends upon the characteristic properties of the matter that comes in the way(of propagation) that can be studied. To proceed further we need to recall Fourier’s theorem which states that any periodic variation (‘of what?’. ‘you choose’) can be resolved into a ‘fundamental’ frequency of Sinusoid and its multiples called ‘harmonics’ (linearly) added. Now ‘Sinusoid’ (Sine wave), a very popular mathematical representation is chosen (of several ‘representations’) as the ‘basis’ whose time per cycle is the reciprocal called ‘frequency’ and whose extent in space (length) is called ‘wavelength’. I’ll stop here.
Depending upon 4 parameters (this is my theory) of the matter (even the ‘medium’ you are referring to is the same)
the magnetic permeability (‘m`u’) in free space,
the electric permittivity (‘epsilon’) in free space,
‘resistivity'(‘rho’), the factor responsible for electrical resistance in the propagation of electric current,
and ‘conductivity’ (‘g’), the factor responsible for leakage of current between parallel current flows.
At certain bands of frequencies, the matter appears as a ‘dielectric’ allowing EM waves (light also) to propagate through it, without any being reflected (scattered) back. Some other matter for the same frequencies blocks the waves; returning (reflecting) it back. Interface between a dielectric (matter) & medium gives rise to the concept of ‘Refractive index’ that all Science undergraduate students are familiar. At “light” frequencies glass behaves as a dielectric and metal as reflector (and many more substances). It is the reflection that gives out the material body that we ‘see’, because of its reflecting properties. Moon & planets are examples. Stars generate their EM waves and we see that as their dazzling radiance down to ‘glow’ like an ember. A ‘flame’ glows because it ‘generates’ EM waves (“light”), by converting chemical energy.

• Michael Z says:

Light DOES NOT need a medium to travel through so it is able to travel anywhere in space.

• wilde_space says:

Light is waves in electromagnetic field, and this field is everywhere.

• Philip J says:

Alan & George are spouting the politically correct establishment view–which is totally wrong! All waves require a medium. The medium of light is the ether, which I believe is also the medium of electrostatic force, the strong nuclear force and gravity. Light waves propagate in the manner of acoustic shear waves in a solid medium.

The ether is an ultra-dense, ultra-stiff solid. It has the form of a foam. The cosmic foam of our universe is the ether foam of a super-universe, and the ether foam of our universe is the cosmic foam of a sub-universe. By “ultra-dense”, I mean the inertial density of the ether is many times greater than that of a neutron star–conceivably a googol times denser–but it has no gravity because it is the medium of gravity. By “ultra-stiff”, I mean the shear modulus is commensurate with the density. The speed of light is âˆš(G/Ï) where G is the shear modulus of ether and Ï is the inertial density of ether.

I believe the sideways motion of the ether, as a photon passes, is a small fraction of a Planck length–the Planck length being roughly the median bubble width of the ether foam. The greater the density of ether, the smaller the wave motion.

The particle nature of light is related to the chaotic nature of matter. Fundamental particles are strange attractors in the chaotic mix of ethereal shear waves and ethereal pressure waves (dark energy). An attractor excludes events which don’t match the properties of the attractor. So shear waves can only be emitted or absorbed in particular quantities. There is no such limitation on shear wave transmission thru the ether, as evidenced by the fact that a photon’s Doppler redshift or blueshift is analog in nature. Photons are only quantized in their interactions with matter.

Material particles consist of orbiting pairs or groups of shear waves. But now, I ‘m straying from the topic.

• Dude says:

Light travels thru a vaccum, whoever is giving all the thumbs down is incorrect.

visible light has enough energy to activate nerve endings in our eyes and send signals to our brain to interpret as colors

• eelfins says:

Space (or rather space-time) can be thought of as an electromagnetic field which light propogates along. If it was not, then light would not be possible. Light seems to travel through space like a wave, and affect matter like a particle. How do we see light? Our eyes evolved that ablity because it’s useful.

• Scott says:

called particulate displacement. pulsons which are microscopic photons can go at instantaneous speeds through time and space in any amount. you cannot see pulsons as they are smaller than your visual cortex and perceive but they are there just look at the center of the sun its helium core contains a variance stream that links intrinsically to all the other stars in the universe through time and space. think of the center of stars as a map of the entirety of the life of the universe. particulate dodecagons(neutrinos ie dark matter) are the mediums which photons travel as empty space is as dense as ice. light are the conductive archs like lightning that all photons travel on through particularized space.

• George says:

(1) — None of the electromagnetic radiation, which also includes radio waves, microwaves, infrared radiation, ultraviolet radiation, X-rays and gamma rays requires a medium to travel.

Sound requires a medium to travel since it is a pressure wave which travels through particles.

(2) — Photons bounce off an object then into ours eyes, which is how we see objects, then your brain converts it into images for you.

• Alan says:

You are thinking of sound, sound needs a medium to travel in, photons travel like bullets, it’s easier through space than atmosphere or glass.

We see objects by reflection, photons bounce off an object straight into your eye where they excite the retina