Questions About Light: Mass, Inertia & Acceleration

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Discussion Overview

The discussion revolves around the properties of light, specifically addressing whether it has mass, inertia, and acceleration. Participants explore theoretical implications and conceptual understandings related to light's behavior in various contexts, including its interaction with gravity and its nature as a wave or particle.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions if light has mass, inertia, and acceleration, suggesting that if light lacks mass, it may not possess inertia or acceleration.
  • Another participant states that light has no rest mass but possesses momentum, citing the equation p = E/c and referencing laser cooling as an example.
  • A different viewpoint suggests that since light has no rest mass, it cannot accelerate, proposing that light reaches the speed of light instantaneously upon creation.
  • One participant reflects on the wave nature of light, expressing uncertainty about its mass and questioning the need for a medium for wave propagation, noting that light can travel through a vacuum.
  • Another participant mentions that light has energy and momentum, referencing experiments like the ESA solar sail and discussing how light can experience centripetal acceleration due to gravitational effects.
  • A further contribution discusses the interaction of light with massive objects, questioning how gravity can influence light's path if it has no mass, and suggests that this may relate to spacetime distortion, pending confirmation from ongoing experiments.

Areas of Agreement / Disagreement

Participants express various viewpoints on the nature of light, with no consensus reached regarding its mass, inertia, or acceleration. The discussion remains unresolved, with multiple competing ideas presented.

Contextual Notes

Some claims depend on specific definitions of mass and inertia, and the discussion includes unresolved assumptions about the nature of light and its interactions with gravity.

Noah
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Not planning to go out on a limb like I did with my magnetism questions/theory.

Does light have mass?
Does light have inertia?
Does light have acceleration?
If light doesn't have mass, then is it even possible for it to have inertia and acceleration?

More questions to come after I get some answers for these.
 
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Light has no rest mass. It does have momentum, p= E/c, and this has been demonstrated by the ability to do laser cooling, to name one example.
 
Not an expert by any means, but my thoughts are: since light has no rest mass it can not accelerate since acceleration is dependent upon mass. However, light has momentum, and momentum with zero rest mass means that light goes from zero to c the very moment it is "created".
 
I'm by no means an expert on this, but I was always thought that light was a wave, so I've understood that it's energy and not mass. I'm probably wrong on this.

The one thing I've always wondered is, all waves need to travel through a medium, but light can travel in a vacuum...
 
That's the old concept of aether. Light has no mass but does have energy. It does have momentum, as exemplified by many experiments, most dramaticaly the ESA solar sail recently launched. Light is bent around the sun, and therefore can experience centripetal acceleration from the Earth reference frame.
 
Light travels E-M waves and interacts as particles. We say that light has no mass in ¿rest? (well, i don't know what is the correct word, but i mean that the v respect to the ground is zero).

But if it has no mass ¿how can a galaxy, a star or even a planet disturb its travel and force it to change its direction? This is what happens with an asteroid for example, the gravity forces it to change... Ok that is solved if we proof that Earth, Sun, and the galaxy at all, disturbs the spacetime... but we have to wait several months, to let Gravity Probe B do its work.
 
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