What movies the particles of light?

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Discussion Overview

The discussion centers around the nature of light, specifically its properties as a particle and wave, its speed, and how it travels through different mediums. Participants explore concepts related to light's mass, the behavior of sound, and the implications of black holes on light. The scope includes theoretical explanations, conceptual clarifications, and some debate over misconceptions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants assert that light is a particle, while others clarify that light photons are bosons, which are massless and travel at the speed of light.
  • There is a discussion about how light can travel through space without a medium, with some suggesting it travels similarly to other particles.
  • Participants debate the nature of sound, with some arguing that sound requires a medium to travel, while others question the assertion that sound cannot travel through solids.
  • One participant mentions that inertia is responsible for light's speed, while another counters that inertia is a property of mass, leading to a discussion about momentum.
  • There is a clarification that light can travel through solids, citing examples like x-rays and mobile phone signals, while others emphasize the role of frequency in this context.
  • Some participants discuss the wave-particle duality of light, with differing views on how to conceptualize light's behavior in quantum mechanics.

Areas of Agreement / Disagreement

Participants express multiple competing views on the nature of light, sound, and the implications of black holes. The discussion remains unresolved with no consensus on several points, including the properties of light and the misconceptions surrounding sound transmission.

Contextual Notes

Some statements reflect misunderstandings or lack of clarity regarding the properties of light and sound, as well as the implications of mass and inertia. There are also references to specific examples and concepts that may require further elaboration or context.

natevi
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Light travels at almost 190,000 MPH per second. Light is a particle just like dust or any other thing. What is making it travel that fast? How does light travel threw space if there's nothing to travel threw? Shouldn't that mean that sound can travel threw everything too? If light can travel threw everything except for solids then why can sound travel threw solids?
To Dave: how is it massless if everything has mass? black holes are so strong they can pull light in so it can't be massless,
Thanks for informing me! That anwsers aloooooot of my questions!
 
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natevi said:
Light is a particle just like dust or any other thing.
No it is not a particle like any other thing.

Light photons are bosons. Bosons are massless and always travel at the speed light.
All matter particles such as dust are fermions, whcih cannot travel at the speed of light.

For some intents and purposes, we can treat light in certain circumstances like it's a particle, but that does not make it a particle of matter. (In some circumstances, my laptop behaves like a boat anchor, but that does not mean it is a boat anchor.)

natevi said:
How does light travel threw space if there's nothing to travel threw?
The same way particles of dust and particles of rocket ships and do.

natevi said:
Shouldn't that mean that sound can travel threw everything too?
Sound is not a physical thing; it is the transmission of vibration from molecule to molecule of a medium. The medium might be air or steel or drywall.
 
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natevi said:
To Dave: how is it massless if everything has mass? black holes are so strong they can pull light in so it can't be massless
Everything does not have mass. Photons do not have mass.

Black holes do not "pull" light. Black holes distort spacetime, causing it to curve back on itself. Massless photons and massive matter both follow curved spacetime.
 
natevi said:
Light travels at almost 190,000 MPH per second. Light is a particle just like dust or any other thing. What is making it travel that fast? How does light travel threw space if there's nothing to travel threw? Shouldn't that mean that sound can travel threw everything too? If light can travel threw everything except for solids then why can sound travel threw solids?
To Dave: how is it massless if everything has mass? black holes are so strong they can pull light in so it can't be massless

Where do you get these ideas and the confidence to assert that they're all correct? I don't understand.

Who said everything had mass?
Who said black holes only attract objects with mass?
Who said light can travel through everything except solids?
Who said sound can't travel through solids? (To the best of my knowledge, I can hear people in the room next door!)
 
Nabeshin said:
Who said sound can't travel through solids?
Certainly not Nabeshin. You misread this one. :wink:
 
natevi said:
What is making it travel that fast? How does light travel threw space if there's nothing to travel threw?

It's called inertia.

Light-speed is merely a specified velocity (without direction). It is the fastest anything can travel, because mass slows an object down, in a sense. Light has no rest mass, so it travels at the fastest pace. It travels, like anything, with a constant speed through space. There is nothing 'mysterious' about it.
 
benk99nenm312 said:
It's called inertia.
No it isn't. Inertia is a property of mass. No mass = no inertia.
 
DaveC426913 said:
No it isn't. Inertia is a property of mass. No mass = no inertia.

Poorly stated (by me), sorry. I think momentum was the word I was looking for.

What I meant is that light doesn't have any inertia. :smile:
 
DaveC426913 said:
Certainly not Nabeshin. You misread this one. :wink:
Though he did say light can't travel through solids, which is wrong...where'd he hear that?
 
  • #10
DaveC426913 said:
Certainly not Nabeshin. You misread this one. :wink:

You're right, I got caught up in it all.

Still I seriously think it's a valid question, where do people hear this kind of stuff?? Is it in books or magazines or is it just the reader (citizen) interpreting vague statements and combining with common sense to reach completely wrong conclusions?

PS: Natevi, it's better to post a response rather than edit your original post... Just don't go overboard with this new found freedom.
 
  • #11
DaveC426913 said:
Light photons are bosons. Bosons are massless and always travel at the speed light.
All matter particles such as dust are fermions, whcih cannot travel at the speed of light.
Er, while photons are indeed bosons, this alone does not indicate that they are massless. A boson is just an integer-spin particle, and we are aware of a number of bosons which have mass (the W and Z bosons, for instance, and many atoms behave as bosons as well).

It is fundamentally the massless property of light, not the bosonic property, that causes it to always travel at the speed of light. The two properties are not identical. The bosonic property of light (and other matter) usually only causes interesting effects at extremely low temperatures. For example, Helium-4, which is bosonic, becomes a superfluid at 2.17K, while Helium-3, which is fermionic due to the odd number of total fermions, becomes a superfluid at about 0.0025K, as it has to get cold enough that the Helium-3 atoms form pairs to become bosons.
 
  • #12
In the fine Hollywood tradition of physics:

DUCK -- HERE COMES A PHOTON!​
 
  • #13
natevi said:
How does light travel threw space if there's nothing to travel threw? Shouldn't that mean that sound can travel threw everything too? If light can travel threw everything except for solids then why can sound travel threw solids?

Light can be a particle or it can be a wave, any reasonable book will explain the mechanics of it, In space light has what is called wave-particle duality. the particles travel on the wave and the wave carries the particle. This is why light can travel through space. Sound hower has entirely different mechanical properties. It needs a medium to travel through, sound is pressure pushing on e.g. air, when the air hits your ear drum the ear drum vibrates at a frequency denoted by the air hitting your eardrum...thats why sound cannot travel through space, there is no medium (be it air or water etc etc)..

Actually light can travel through solids...otherwise we wouldn't have x-rays etc etc, its the frequency of the light that will determine what it can travel through, eg. gamma rays. If light couldn't travel through solids then how do you explain being able to make a call off your mobile...mobiles operate in the microwave spectrum...

If you can find a book called "x stands for unknown" auther Isaac Asimov it explains the light spectrum in very simple terms, very easy to understand. You might find it in the library, the other chapters are just as interesting too if you are interested in physics

Hope this helps.
 
  • #14
Bodicea said:
Light can be a particle or it can be a wave,
Actually, it's just a quantum-mechanical particle, which means it has wave-like qualities as well. It is neither a wave nor a particle in the sense of a macroscopic wave (like an ocean wave) or a macroscopic particle (like a piece of dust). It's a weird quantum thing that has properties of both (as with all quantum particles).

Basically what this means is that if you describe a photon by using its quantum-mechanical wave function, you can accurately reproduce all of its behavior just by evolving that wavefunction forward in time (provided you also have the wavefunctions of everything it interacts with, too). There is no transition where you have to think of the particle as anything but just following the dynamics of the wavefunction.

Anyway, that's my bit of pedantry for the time being.
 
  • #15
Light travels with v<c in transparent mediums.

Bob_for_short.
 
  • #16
Bob_for_short said:
Light travels with v<c in transparent mediums.

Bob_for_short.

Yeah, thanks to electrons. The time it takes for electrons to absorb and emit the photon is what 'slows' the photon down. The photon still moves at speed c.
 
  • #17
benk99nenm312 said:
Yeah, thanks to electrons. The time it takes for electrons to absorb and emit the photon is what 'slows' the photon down. The photon still moves at speed c.

Wrong. For a transparent medium there is no absorption, there is no delay due to "delayed" radiation. There is a collective effect, that is true, but it is a superposition of the incident wave and continuously oscillating and thus radiating electrons. That makes the resulting EMF velocity smaller than c. There is no de-phase phenomenon due to spontaneous absorption and delayed emission.

Bob for short.
 
  • #18
Bob_for_short said:
Wrong. For a transparent medium there is no absorption, there is no delay due to "delayed" radiation. There is a collective effect, that is true, but it is a superposition of the incident wave and continuously oscillating and thus radiating electrons. That makes the resulting EMF velocity smaller than c. There is no de-phase phenomenon due to spontaneous absorption and delayed emission.

Bob for short.

I looked this up. Fascinating. I never new that. My apologies.
 

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