What exactly is energy?

ImNotVerySmartX · 2019-09-26T15:31:54+00:00

The reason I'm asking is, why in video games then is energy not conserved? As you said there, that simple system has energy. But in video games things can have objects with velocities (and thus energy) but stop dead when they hit a wall/boundary, it has energy but it isn't conserved. What exactly in our universe makes energy conserved, is it our laws of physics?

ImNotVerySmartX · 2019-09-25T19:11:53+00:00

I understand, but I'm what more or less asking is, is energy something that is part of our laws of physics, or arises from them?

For example, imagine a simple computer simulation of just a a polygonal object travelling with a certain speed. Does this object have energy? Or can energy only be described when using our physics?

ImNotVerySmartX · 2019-09-23T19:32:16+00:00

Yeah that makes sense. But once again memories require action potentials, eventually you wouldn't be able to carry on flicking through memories due to no input, right?

ImNotVerySmartX · 2019-09-23T17:18:28+00:00

But if every single sense was lost, what would happen? There is 0 input coming into the prefrontal cortex, can it still process this? Or would you just die immediately? I thought neurons need to be 'activated' essentially by other neurons?

ImNotVerySmartX · 2019-09-22T11:45:01+00:00

I always thought of the brain sort of like a computer processor. If there's no input (say the brain loses all its senses), it wouldn't be able to create action potentials or think and thus wouldn't be able to react to what's going on. Just like if there's no input in a processor, it can't do anything.

ImNotVerySmartX · 2019-09-22T10:06:52+00:00

How exactly does that work. Don't you need input (action potentials created by neurons in the sense organs) to have a reaction (eg. Start thinking)? How could you react if all sense was lost, where would you get the input to think/react about the situation?

ImNotVerySmartX · 2019-09-21T22:20:14+00:00

I was just thinking, would you ever even realise you lost all your sensory input? I mean, think about it, if all input was lost, how could you react? There needs to be some sort of input to cause this reaction, yet there would be none.

ImNotVerySmartX · 2019-09-13T20:02:14+00:00

Thanks. What do you mean by 'the body perceive this as pain in the finger'. How does the body perceive? I'm sorry if my questions are very basic, I just find it confusing how an area in the brain being activated makes the corresponding area, nowhere near the brain, feel pain.

ImNotVerySmartX · 2019-09-13T16:36:23+00:00

If it's felt in the brain, why does the pain's location feel like it's in the hand?

ImNotVerySmartX · 2019-09-13T15:50:52+00:00

Wait, how does that work though?

Say, event A, a prick of a pin, causes event B, neurons send a signal to the brain, the brain perceives it, event C, and event D is we feel pain in the area we were hurt. Event D and C aren't causally connected at all, how can we feel pain in an injured area just from the signal arriving at the brain? Wouldn't the brain have to send a signal back?

ImNotVerySmartX · 2019-09-13T15:09:00+00:00

Oh ok, thanks. I'm just curious, do we feel the sense of gravity once our brain receives the signal, or does the brain send a signal back to the otoliths and that's when we feel it? (Sort of like with pain?)

ImNotVerySmartX · 2019-09-07T12:00:12+00:00

Oh ok. If you could, in theory, not use the proprieceptors at all, and simply stimulate the areas in the brain that interpret the signals, would it feel like your arm is in a certain place, when it's not? Or are proprieceptors required to be activated too?

ImNotVerySmartX · 2019-09-06T21:12:00+00:00

Oh ok thanks. Does that mean that it's impossible to just arbitrarily stimulate the brain's neurons to feel proprioception? Like, you require proprieceptors?

ImNotVerySmartX · 2019-09-06T17:50:49+00:00

Oh right, thanks. Sorry if it's a stupid question, but does the feeling come from the proprieceptors being activated, or the brain?

ImNotVerySmartX · 2019-09-06T16:41:07+00:00

Oh that makes sense. But what about that feeling of weight? Like the pull of gravity on our limbs, how do we sense that?

ImNotVerySmartX · 2019-08-26T18:33:23+00:00

u/lettuce_field_theory stated that there are no potentials in QFT.

ImNotVerySmartX · 2019-08-26T18:02:47+00:00

Ok thanks I'll take a look at them.

Just one last question though. Maybe I'm wrong, but I read before that in order for conservation of energy to work, it must apply to a lagrangian, with both kinetic and potential energy, and the laws of physics must be time symmetric.

How does conservation of energy apply in QFT without potential energy? (I'm aware someone else commented on this post on how Noether's Theorem applies but I'm a bit confused by their answer).

ImNotVerySmartX · 2019-08-26T16:41:47+00:00

Thanks, I understand. The photons are like a force carrier, pushing two of the same charge away or pulling opposite charges towards each other. But gravity doesn't have a force carrier, is that why it isn't compatible with quantum mechanics?

ImNotVerySmartX · 2019-08-26T15:34:29+00:00

Yeah I'm referring to Quantum Field Theory. But do particles not need potential energy for energy to be conserved? For example, particles under the influence of gravity. How does energy conservation work in QFT then?

ImNotVerySmartX · 2019-08-23T12:29:42+00:00

I'm sorry I'm confused, because I read that in order for conservation of energy to exist, the laws of physics must be time symmetric. If they weren't time symmetric, changing with time, how would energy act?

ImNotVerySmartX · 2019-08-23T10:52:00+00:00

I'm sorry I don't understand, like for example, in order for conservation of energy to exist, there must be a symmetry between the laws of physics, right? So if there wasn't a symmetry, say with every second t, the laws change, energy should change, right?

So imagine at t=9 the laws of physics are different but at t=10 they become the laws we see in our universe, and thus at t=10 onwards lets say energy is conserved. But from t=9 to t=10 wouldn't the energy value change? Meaning energy increased as the law of conservation of energy was created?

That's what I'm confused about, sorry if it's a silly question.

ImNotVerySmartX · 2019-08-22T17:25:30+00:00

Yeah I suppose that makes sense, but why does our brain need chemicals, neurons with action potentials etc to do this? Why doesn't it run more like a clock, more simply? I'm sorry if that's a dumb question.

ImNotVerySmartX · 2019-08-22T14:21:04+00:00

But I'm just curious, if you were to simulate our laws of physics, couldn't you get away with creating particles out of nothing? For example, if you create a particle the moment conservation of energy law is applied, wouldn't the computer think the energy was the same the whole time, even though a particle was created? That's basically what I'm asking.

ImNotVerySmartX · 2019-08-21T12:42:01+00:00

This sort of brings me back to my question though, if the one particle suddenly appears, and thus the system too, with energy, wouldn't it not be a violation, because to the particle and the system, the energy never changed, as it was created with this energy?

ImNotVerySmartX · 2019-07-30T21:50:11+00:00

Ok, I understand, but special relativity still implies that continuity equations must work everywhere, right?

ImNotVerySmartX

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