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A compressed spring weighs more than the same spring uncompressed. The moon and earth weigh less together than if you weighed them separately and added the valu

A compressed spring weighs more than the same spring uncompressed. The moon and earth weigh less together than if you weighed them separately and added the values together. Most of the weight of solid objects is due to the high speeds and binding energies of the elementary particles within them rather than the rest mass of the constituent particles. The number of particles that exist is relative to how fast you are accelerating. Everything that has energy (which is everything we know of) affects the gravitational field; this means that even photons are "attracted" to each other. A non-relativistic quantum state will return arbitrarily close to its initial state an infinite number of times. There is such a thing as interaction-free measurements: you can take photos of things without ever letting light hit a detector and you can tell whether a bomb is "active" without actually interacting with the detonator. Energy is just a number that is calculated as a function of the state of a closed system — that this number is a constant results from the time transitional invariance of the laws of physics. Similarly, conservation of momentum is due to the spatial invariance of the laws of physics, and conservation of angular momentum is due to rotational invariance. Also, conservation of energy does not hold under general relativity.

iheartblocks 6y ago
> There is such a thing as interaction-free measurements: you can take photos of things without ever letting light hit a detector and you can tell whether a bomb is "active" without actually interacting with the detonator. Can you provide a link that talks about that? It goes against my understanding of why there's an uncertainty principle at all
AnotherGoodName 6y ago
>Most of the weight of solid objects is due to the high speeds of the elementary particles within them rather than the rest mass of the constituent particles. Wait i agree energy is mass but is this specifically correct? The rest mass is always much higher when i've seen it in equations.
- Xcelerate 6y ago
  Whoops, I forgot binding energy. But yes, rest mass of quarks is only about 1% of a proton or neutron’s mass.
throw1234651234 6y ago
>A compressed spring weighs more than the same spring uncompressed. This is false. The dilemma is that you can't "just weigh" a compressed spring without assistance. However, you can get around it by weighing a compression device with the spring, both when it's compressing and not compressing the spring. The weight will be the same.
- Xcelerate 6y ago
  You could not practically ever measure the difference in a lab, but it’s still a real effect. Look up the stress-energy tensor. I could equivalently say that a spinning ball weighs more than the same ball when stationary.
  - throw1234651234 6y ago
    W=mg Weight is mass times gravity. It is the mass of the object. As affected by a single force - gravity. Gravity is a force. A spinning ball has ANOTHER force acting on it, and therefore cannot be defined by "weight". In short, this is an absurd statement that tries to redefine a scientific definition for...I don't even know? Sensationalism?
    - Xcelerate 6y ago
      You are not considering the effect of general relativity. See theoretical physicist Professor Matt Strassler's page where he gives the exact same example of how energy can be stored that I did: https://profmattstrassler.com/articles-and-posts/particle-physics-basics/mass-energy-matter-etc/mass-and-energy https://profmattstrassler.com/articles-and-posts/particle-ph.... All forms of energy, including potential energy in the form of a compressed/stretched spring, couple to the gravitational field. Again, read about the stress-energy tensor for how this works. > In short, this is an absurd statement that tries to redefine a scientific definition for...I don't even know? Sensationalism? What I've said is not even remotely controversial in the physics community. Don't take my word for it; ask anyone who has taken a basic graduate course in general physics and they will agree that a compressed spring or a spinning ball weighs an imperceptibly (i.e., immeasurably) small amount more than the uncompressed spring or stationary ball, should you have a hypothetical scale that was so precise as to be able to measure the difference.
thaumasiotes 6y ago
> The number of particles that exist is relative to how fast you are moving. I thought the existence of particles was relative to how fast you're accelerating? If it's relative to how fast you're moving, wouldn't that imply that absolute velocity exists, i.e. that given two objects with known relative velocity to each other, we could potentially establish which one was "really" moving and which one was "really" still?
- Xcelerate 6y ago
  Should have said how fast you are accelerating. Edited now. See http://www.scholarpedia.org/article/Unruh_effect http://www.scholarpedia.org/article/Unruh_effect
fragmede 6y ago
Similarly, a fully charged Tesla (or other electric) vehicle weighs more than an uncharged one. The difference is roughly the weight of 10 human hairs, so it's absolutely negligible, but that application of E=MC^2 blew my mind the first time I saw it.

iheartblocks 6y ago

> There is such a thing as interaction-free measurements: you can take photos of things without ever letting light hit a detector and you can tell whether a bomb is "active" without actually interacting with the detonator. Can you provide a link that talks about that? It goes against my understanding of why there's an uncertainty principle at all

AnotherGoodName 6y ago

>Most of the weight of solid objects is due to the high speeds of the elementary particles within them rather than the rest mass of the constituent particles. Wait i agree energy is mass but is this specifically correct? The rest mass is always much higher when i've seen it in equations.

Xcelerate 6y ago
Whoops, I forgot binding energy. But yes, rest mass of quarks is only about 1% of a proton or neutron’s mass.

throw1234651234 6y ago

>A compressed spring weighs more than the same spring uncompressed. This is false. The dilemma is that you can't "just weigh" a compressed spring without assistance. However, you can get around it by weighing a compression device with the spring, both when it's compressing and not compressing the spring. The weight will be the same.

Xcelerate 6y ago
You could not practically ever measure the difference in a lab, but it’s still a real effect. Look up the stress-energy tensor. I could equivalently say that a spinning ball weighs more than the same ball when stationary.
- throw1234651234 6y ago
  W=mg Weight is mass times gravity. It is the mass of the object. As affected by a single force - gravity. Gravity is a force. A spinning ball has ANOTHER force acting on it, and therefore cannot be defined by "weight". In short, this is an absurd statement that tries to redefine a scientific definition for...I don't even know? Sensationalism?
  - Xcelerate 6y ago
    You are not considering the effect of general relativity. See theoretical physicist Professor Matt Strassler's page where he gives the exact same example of how energy can be stored that I did: https://profmattstrassler.com/articles-and-posts/particle-physics-basics/mass-energy-matter-etc/mass-and-energy https://profmattstrassler.com/articles-and-posts/particle-ph.... All forms of energy, including potential energy in the form of a compressed/stretched spring, couple to the gravitational field. Again, read about the stress-energy tensor for how this works. > In short, this is an absurd statement that tries to redefine a scientific definition for...I don't even know? Sensationalism? What I've said is not even remotely controversial in the physics community. Don't take my word for it; ask anyone who has taken a basic graduate course in general physics and they will agree that a compressed spring or a spinning ball weighs an imperceptibly (i.e., immeasurably) small amount more than the uncompressed spring or stationary ball, should you have a hypothetical scale that was so precise as to be able to measure the difference.

thaumasiotes 6y ago

> The number of particles that exist is relative to how fast you are moving. I thought the existence of particles was relative to how fast you're accelerating? If it's relative to how fast you're moving, wouldn't that imply that absolute velocity exists, i.e. that given two objects with known relative velocity to each other, we could potentially establish which one was "really" moving and which one was "really" still?

Xcelerate 6y ago
Should have said how fast you are accelerating. Edited now. See http://www.scholarpedia.org/article/Unruh_effect http://www.scholarpedia.org/article/Unruh_effect

fragmede 6y ago

Similarly, a fully charged Tesla (or other electric) vehicle weighs more than an uncharged one. The difference is roughly the weight of 10 human hairs, so it's absolutely negligible, but that application of E=MC^2 blew my mind the first time I saw it.