Why do we think light travels the same as sound? Some questions for astrophysics folks out there

[Space Lynx]

I been thinking a lot about this lately, if sound requires a medium to travel upon, such as air, then light would need a medium too yes and in deep space the only medium is dark matter/dark energy I think, so deep space is not nothing, there is a medium, but that medium is not consistent? I believe the earliest physicists called this the Aether or something since they didn't know about dark matter and energy yet, not so much interested in that as I am the idea that light might not travel at all. I'm aware it takes time for light to reach us from far away, I am aware this is measurable phenomena, but what if the reason it takes time to get to us isn't because of distance and time? Is it possible there is another mechanism at play that slows light down, maybe micro-bends in gravity that we can't measure, besides sheer distance? I think the bending nature of gravity at the Cosmic scale still has more to teach us about how things travel, in this case light... what if the material substance (even though we can't see it) that gravity is bending well it all has to be connected at some sort of cosmic scale, all bending the same field of substance regardless of location within the visible Cosmos -localized bending of gravity in relation to size seems obvious and clear and has been calculated, but gravity itself as a medium - since if we were to say

Gravity inherently is bending something, not nothing... that nothing is everywhere in the Cosmos even if we can't measure it, it is therefore the medium light travels upon no? this would be a consistent medium for light to travel upon, the fabric that gravity bends, even if you removed dark energy from places, dark matter, and so forth. light travels still without dark matter or dark energy present, therefore, don't we have to conclude there is another medium of travel? it has to be the fabric that gravity bends, which is present everywhere, and I don't necessarily believe that gravity is bound by the rules of distance and time

@lexluthermiester have I lost my mind?

 

[the54thvoid]

Observable light is delivered to our eyes in packets of photons. It is part of a wavelength.

Sound requires physical particles as hearing is based on the vibration of anatomical structures.

The above is very crude but it explains why light and sound travel differently. Light requires no physical medium, sound propagates through a physical medium.

 

[Space Lynx]

Observable light is delivered to our eyes in packets of photons. It is part of a wavelength.

Sound requires physical particles as hearing is based on the vibration of anatomical structures.

The above is very crude but it explains why light and sound travel differently. Light requires no physical medium, sound propagates through a physical medium.

a wavelength, this concept is hard for me to understand, but it does make sense. surely even wavelengths have a physical substance, just at a level we can't measure? how is something not nothing? agh i guess i just am not smart enough to understand these things, but ty for trying lol

 

[mechtech]

It doesn’t. They both travel at different speeds through different mediums.

 

[Selaya]

Wave–particle duality - Wikipedia

en.wikipedia.org

 

[Space Lynx]

It doesn’t. They both travel at different speeds through different mediums.

I still don't understand what the medium is for light though, as there is nothing consistent in the Cosmos other than the fabric that gravity bends.

 

[gurusmi]

I live in Germany. We use only the metric system,
In easy figures both begin with 300. Both differences only by three simple ("0") digits.

Sonic: 300m/sec
light 300.000m/sec.

It is easy to calculate how far a lightning is away. One sees the light and start to count the seconds till it bangs. Multibly it by 300 and voila. There is the distance in meters.

 

[A Computer Guy]

I still don't understand what the medium is for light though, as there is nothing consistent in the Cosmos other than the fabric that gravity bends.

I like to think of the fabric of the universe as a fine gnocchi soup. When light is absorbed by it the flavor increases and the light reflected shows you a nice view. Then when you microwave it the dumplings get really nice and hot. As you place your spoon into the soup you think its going rather slowly at fractions of centimeters per second but in reality it is going many thousands of kilometers per second since the earth is moving too. Thankfully it doesn't splash out and get all over the table and some thank god for that. I know that's a bit deep but hopefully clears things up a bit.

 

[Space Lynx]

I like to think of the fabric of the universe as a fine gnocchi soup. When light is absorbed by it the flavor increases and the light reflected shows you a nice view. Then when you microwave it the dumplings get really nice and hot. As you place your spoon into the soup you think its going rather slowly at fractions of centimeters per second but in reality it is going many thousands of kilometers per second since the earth is moving too. Thankfully it doesn't splash out and get all over the table and some thank god for that. I know that's a bit deep but hopefully clears things up a bit.

This was surprisingly helpful, lol

 

[LabRat 891]

Uhhh... Who thinks EM waves travel like (linear) sound waves?

One cursory 'lookup' of why/how Silver, Gold, etc. lustre as they do, tells ya 'light'
"ain't so simple"
(See also: double slit experiment. And Entangled Photons)

The way I figure,
EM waves are energy-vibrations that represent data/information in physical reality.

Factor in 'informational radiation' (mathematically theorized as emanating from Black Holes)
and you start to feel like you're looking at
"The other side of E=MC^2"

 

[authorized]

I still don't understand what the medium is for light though, as there is nothing consistent in the Cosmos other than the fabric that gravity bends.

The medium is electromagnetic field, which is everywhere. I don't think there's a deeper understanding currently, we consider it a property of spacetime, it's just there.

 

[Space Lynx]

Uhhh... Who thinks EM waves travel like (linear) sound waves?

One cursory 'lookup' of why/how Silver, Gold, etc. lustre as they do, tells ya 'light'
"ain't so simple"
(See also: double slit experiment. And Entangled Photons)

The way I figure,
EM waves are energy-vibrations that represent data/information in physical reality.

Factor in 'informational radiation' (mathematically theorized as emanating from Black Holes)
and you start to feel like you're looking at
"The other side of E=MC^2"

do photons not have mass? because if they do that's physical.

The medium is electromagnetic field, which is everywhere. I don't think there's a deeper understanding currently, we consider it a property of spacetime, it's just there.

deep parts of space completely empty though, so how does light still travel through it? i thought electromagnetic fields are only within galaxies and maybe a little further out, and clustered here and there?

 

[Shrek]

If there was a medium, the speed would be relative to that medium; they looked
Michelson–Morley experiment - Wikipedia
the speed of light is an absolute (Einstein thought to use the word absolute in the naming of what we now call the theory of relativity).

 

[Space Lynx]

I looked it up, photons are massless, so fascinating, light has no mass - yet in its creation, instantly travels faster than anything, maybe Light is God?

all hail Apollo indeed

does different light travel at different speeds? like a candle lit in a room vs the Sun giving off light? or are both traveling at same speed at moment of spark? if answer is yes, I vote we retire this thread and just say Light is God's manifestation, and we begin to hold rituals chanting around fires

If there was a medium, the speed would be relative to that medium; they looked
Michelson–Morley experiment - Wikipedia
the speed of light is an absolute (Einstein thought to use the word absolute in the naming of what we now call the theory of relativity).

but what if the fabric that gravity bends in the Cosmos is the medium, that can't be measured, or seen, cause we have no idea what it is

 

[mechtech]

I still don't understand what the medium is for light though, as there is nothing consistent in the Cosmos other than the fabric that gravity bends

Well the medium is anything light travels through, in space mainly the empty void of vacuum & emptiness. On earth, the atmoshpere, water, windows, etc.

Sound, humans mainly consider air, since it's how we 'hear', however it travels at different speeds through water, steel, etc. as well. Funny thing is physcial sound as we define it does not travel through a vacuum like space and light does not goes through things that are not opaque/translucent/transparent, hence shadows.

Then again, not really sure I understand your question. Maybe I need gravity to bend my mind around it.

edit - try out this channel

maybe he can help

edit 2 - ooooooooooo

https://www.youtube.com/results?search_query=fermilab+light

 

[R-T-B]

all hail Apollo indeed

Greeks had it wrong Apollo was the god of speed all along.

 

[AusWolf]

a wavelength, this concept is hard for me to understand, but it does make sense. surely even wavelengths have a physical substance, just at a level we can't measure? how is something not nothing? agh i guess i just am not smart enough to understand these things, but ty for trying lol

Light has traits that resemble both particles and waves. Even physicists can't fully understand it, as far as I know.

 

[Shrek]

I looked it up, photons are massless

They have energy and so mass.

Sure they have zero rest mass, except they are never at rest.

 

[Count von Schwalbe]

Greeks had it wrong Apollo was the god of speed all along.

We need winged shoes for racing drivers

I looked it up, photons are massless, so fascinating, light has no mass - yet in its creation, instantly travels faster than anything, maybe Light is God?

Remember, mass and energy are in a way the same thing. A photon has the energy of 300km/s, always. It cannot be slowed down - time itself bends to the speed of light.

A good explanation I found on stackexchange:

You are confusing to different concepts. The photon is a particle whereas the classical description of light is a wave, vibrating or oscillating electric and magnetic field vectors. The dual description is the hallmark of quantum mechanics and quantum field theory. The same could be said of material particles like the electron. They have an associated frequency but they do not "vibrate" in the traditional sense.

Material vibrations occur in acoustics and are oscillations in a material like air, water, or elastic solids (there are other examples). Our experience leads us to expect "vibrations" need a medium. For a long time people thought this was true of light and postulated an ether for light waves to travel in. In the late 1800s to early 1900s we discovered that there was no need for this and that we could describe "light" as oscillations in electric and magnetic field vectors. This is a classical mechanics description of light.

Experiments seem to indicate that light (which we thought of as a wave) has particle like properties and that matter (electrons, protons, etc which we thought of as particles) could behave like waves. This led to the development of quantum mechanics in which particle-wave duality is an underlying paradigm.

Any particle has an associated frequency and wavelength related to its energy and momentum. Similarly any quantized field (like light) has associated particles related to its irreducible quantum states.

In the context of QM and QFT any "particle" has a frequency even thought that particle is not necessarily vibrating in the classic sense of acoustics.

 

[lexluthermiester]

Before I begin, a few qualifiers. The terms "Cosmos" and "Universe" are not synonyms and are not interchangeable. "Cosmos" literally translated means "All things", it is more widely defined as "Everything, Everywhere". The "Universe" is only that matter which sprang forth from the Big Bang. Our Universe exists within the Greater Cosmos at large. They are not one in the same.

then light would need a medium too yes

No. Light is made up of particles(photons) that travel through space and any substance that is photonically transparent. Sound is the transmission of kinetic energy through matter.

so deep space is not nothing, there is a medium

No, space is the absence of matter, mostly, which is why their is no sound in space(regardless of what is presented in Science Fiction).

I believe the earliest physicists called this the Aether

True, and they were incorrect.

something since they didn't know about dark matter and energy yet

Dark matter/energy are theoretical constructs. There is no proof of the actual existence of dark matter/energy. Some scientists, like myself, lean toward a different explanation.

I'm aware it takes time for light to reach us from far away, I am aware this is measurable phenomena, but what if the reason it takes time to get to us isn't because of distance and time? Is it possible there is another mechanism at play that slows light down, maybe micro-bends in gravity that we can't measure, besides sheer distance? I think the bending nature of gravity at the Cosmic scale still has more to teach us about how things travel, in this case light... what if the material substance (even though we can't see it) that gravity is bending well it all has to be connected at some sort of cosmic scale, all bending the same field of substance regardless of location within the visible Cosmos -localized bending of gravity in relation to size seems obvious and clear and has been calculated, but gravity itself as a medium - since if we were to say

Gravity does affect light, it's path and in rare situations, it's velocity. Gravity can both change the direction photons are traveling and their rate of travel.

Gravity inherently is bending something, not nothing...

Almost. The "curvature of space", as referred to by Einstein, is a metaphor. Space doesn't actually curve and is not "bent" by gravity.

that nothing is everywhere in the Cosmos even if we can't measure it, it is therefore the medium light travels upon no?

No. Again, space is the absence of matter through which photons of light travel.

Think of it like this: Photons of light are very tiny particles being shot out into the Universe similar to a bullet being shot from a rifle. Both have been launched in a particular direction at a particular velocity. Both will continue on until interacted with by matter, energy or a force. In completely empty space, both would continue on forever. But in our Universe, filled with matter, energy and forces, both will be interacted with at one point or another. The bullet being enormously larger in size and mass than a photon, will be constantly interacted with as it is being bombarded with photons and other forms of energy. It will eventually collide with something and change in both shape and trajectory. The Photon will continue on until it hits something(a piece of dust, a planet, whatever) and is either absorbed, refracted or reflected.

I don't necessarily believe that gravity is bound by the rules of distance and time

Oh, but it is. Gravity is bound by many factors, distance and time being two of the tree primary variables, the third being the mass of the object generating the gravity field in question. The further you get from a gravity field the weaker it's influence on you becomes. That is how the Voyager and Pioneer probes have left the Solar System and off into interstellar space. If gravity was not affected by distance and time, the Big Bang would never have taken place. But here we are..

I looked it up, photons are massless

Not quite. They have a very small mass, relative to our scales of measurement, but they do have mass. Photons are very small. Similar to Electrons but less massive.

the speed of light is an absolute (Einstein thought to use the word absolute in the naming of what we now call the theory of relativity).

That is incorrect. The velocity of light is dependent on a number of factors, including proximity to a gravity field. While we have established the speed of light in general terms, that measurement is not constant.

 

[Space Lynx]

Well the medium is anything light travels through, in space mainly the empty void of vacuum & emptiness. On earth, the atmoshpere, water, windows, etc.

going to watch both of these tonight, thanks!

I don't understand the concept of a void of emptiness in space, for example, if I were to say magically take a planet or the sun, and move them to any void in space you choose, they would immediately bend the fabric their based on their size/gravity - so in fact its not nothing there at all, there is something there and its bending it. maybe these videos will help me though, thank you, watching soon

Gravity does affect light, it's path and in rare situations, it's velocity. Gravity can both change the direction photons are traveling and their rate of travel.

this is where I am stuck, the rest of your post makes a lot of sense to me. I understand what you mean when you say it doesn't bend, its just those visual images that show the bending based on size that trip me up here, because this indicates even the void itself is not nothing, if it can be manipulated by a larger object, then maybe light uses this "fabric" as a medium? even if we can't see or understand it.

 

[lexluthermiester]

this is where I am stuck, the rest of your post makes a lot of sense to me. I understand what you mean when you say it doesn't bend, its just those visual images that show the bending based on size that trip me up here, because this indicates even the void itself is not nothing, if it can be manipulated by a larger object, then maybe light uses this "fabric" as a medium? even if we can't see or understand it.

To me, it seems the point you're stuck on is the idea of complete emptiness. It is something that is real.

 

[AusWolf]

going to watch both of these tonight, thanks!

I don't understand the concept of a void of emptiness in space, for example, if I were to say magically take a planet or the sun, and move them to any void in space you choose, they would immediately bend the fabric their based on their size/gravity - so in fact its not nothing there at all, there is something there and its bending it. maybe these videos will help me though, thank you, watching soon



this is where I am stuck, the rest of your post makes a lot of sense to me. I understand what you mean when you say it doesn't bend, its just those visual images that show the bending based on size that trip me up here, because this indicates even the void itself is not nothing, if it can be manipulated by a larger object, then maybe light uses this "fabric" as a medium? even if we can't see or understand it.

View attachment 313728

Look up quantum field theory. I might be getting it wrong (someone please correct me if that's the case), but my understanding is this:

If you imagine the universe as a collection of fields representing different energy states, then particles are a point of non-zero energy state in a certain field, like a vibration on a guitar string, whereas emptiness is the field at an equilibrium, or zero energy state. You can argue that the guitar string exists even at a zero energy state, the same way the universe exists even in areas where the particle density is zero. Spacetime that "bends" is the field, not the particles in it.

Gravity and light propagate through emptiness because gravity affects the quantum field, and light is made up of particles that travel at light speed until they hit something. Sound doesn't propagate through emptiness because it's just the resonance of different particles, but in emptiness, there are no particles to resonate. Light is a particle. Sound is only the effect that some particles have on your eardrums.

 

[Space Lynx]

Look up quantum field theory. I might be getting it wrong (someone please correct me if that's the case), but my understanding is this:

If you imagine the universe as a collection of fields representing different energy states, then particles are a point of non-zero energy state in a certain field, like a vibration on a guitar string, whereas emptiness is the field at an equilibrium, or zero energy state. You can argue that the guitar string exists even at a zero energy state, the same way the universe exists even in areas where the particle density is zero. Spacetime that "bends" is the field, not the particles in it.

Gravity and light propagate through emptiness because gravity affects the quantum field, and light is made up of particles that travel at light speed until they hit something. Sound doesn't propagate through emptiness because it's just the resonance of different particles, but in emptiness, there are no particles to resonate. Light is a particle. Sound is only the effect that some particles have on your eardrums.

this helps yeah. going to have to look more into this

 

[the54thvoid]

I vote we retire this thread and just say Light is God's manifestation, and we begin to hold rituals chanting around fires

If you want to do that, feel free to leave the science discussions.