Does inertia apply to everything in the universe? Even subatomic?

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Discussion Overview

The discussion revolves around the concept of inertia and its applicability to all entities in the universe, including subatomic particles. Participants explore the relationship between mass and inertia, the nature of massless particles, and the implications for energy and motion.

Discussion Character

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

Main Points Raised

  • Some participants assert that inertia applies to everything with mass, including subatomic particles.
  • Others mention that certain particles, like neutrinos, were once thought to be massless but are now believed to have a very small mass.
  • There is a discussion about whether inertia simply means that energy is required to move a mass, with some participants suggesting that the term "energy" may not be entirely appropriate.
  • One participant notes that photons move at a constant speed and questions why they do not have kinetic energy.
  • Another participant challenges the idea that photons lack kinetic energy, suggesting that their kinetic energy could be related to their momentum.

Areas of Agreement / Disagreement

Participants generally agree that inertia is related to mass, but there is disagreement regarding the status of neutrinos and the interpretation of kinetic energy in relation to photons. The discussion remains unresolved on these points.

Contextual Notes

There are limitations in the discussion regarding the definitions of mass and energy, as well as the implications of inertia for different types of particles. The understanding of massless particles and their properties is also a point of contention.

Quantumgravity
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Does inertia apply to EVERYTHING in the universe? Even subatomic particles? Or is there a certain mass limit where something no longer has the property of inertia?
 
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Quantumgravity said:
Does inertia apply to EVERYTHING in the universe? Even subatomic particles? Or is there a certain mass limit where something no longer has the property of inertia?

No, anything that has mass has inertia, as Russ said above. Of course, there are some particles which physicists believe do not have mass. Neutrinos are an example that comes to mind.
 
Does inertia just mean that it takes energy to move a mass?
 
Quantumgravity said:
Does inertia just mean that it takes energy to move a mass?

"Energy" isn't the right word, but you're moving in the right direction (no pun intended). It's possible for a particle to move without having kinetic energy. Photons, for example, move at a constant vacuum speed c. If an object has inertia, this means that force is required to accelerate it. Newton's Second Law tells us that mass is a resistance to force. So some constant force, when applied to objects of higher mass, will impart less acceleration to them. Thus, you could say that inertia is a measure of how much force is required to accelerate an object at a given rate.
 
Thanks. That clears it up.
But why don't photons have kinetic energy?
 
arunma said:
Of course, there are some particles which physicists believe do not have mass. Neutrinos are an example that comes to mind.

Nope, for the past several years it's been widely accepted that neutrinos do have a very small mass (a few eV or less). It's studied via neutrino oscillations.

The only massless particles now, so far as I know, are the photon, the gluons, and the graviton (if it exists).
 
jtbell said:
Nope, for the past several years it's been widely accepted that neutrinos do have a very small mass (a few eV or less). It's studied via neutrino oscillations.

The only massless particles now, so far as I know, are the photon, the gluons, and the graviton (if it exists).

Oops, looks like I missed the memo! Thanks.
 
But why don't photons have kinetic energy?

I wonder to know why too. I thought photons do have kinetic energy equals to their momentum times the speed of light. Is it correct? Thanks.
 

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