Ask any question you want about Physics

originally posted by: ImaFungi
a reply to: Arbitrageur

Why does the value c², multiplied by m, equal energy?

Dimensional analysis is your friend here.

originally posted by: Bedlam

originally posted by: ImaFungi
a reply to: Arbitrageur

Why does the value c², multiplied by m, equal energy?

Dimensional analysis is your friend here.

originally posted by: ImaFungi
a reply to: Arbitrageur

Why does the value c², multiplied by m, equal energy?

originally posted by: Bedlam
Dimensional analysis is your friend here.

Correct, but a more thorough analysis of how this relationship is a consequence of the speed of light being the same in all inertial reference frames is explained in this 40 minute series of five 8-minute videos (find parts 2-5 in the right hand column of the link). It uses a lot of math but it's math everyone should have learned by the 9th grade:

Special Relativity and E=mc² by DrPhysicsA - Part 1 of 5

www.youtube.com...
He shows the E=mc² derivation at 6.5 minutes in part 5, and could have made the videos shorter if he focused only on that, but he goes off on a couple of interesting tangents like relativity of simultaneity, causality, etc.

originally posted by: Nochzwei
the Einstein ring is wrongly named imo. this observation is due to time compression curves and not due to bending of space.
a reply to: Arbitrageur

Meaningless without... backup... provide theory in the language of mathematics and not in the language of buzzwords

a reply to: ErosA433

I think wt he was holding in his < hand had more to do with planned obsolescence.

originally posted by: Bedlam

originally posted by: ImaFungi
a reply to: Arbitrageur

Why does the value c², multiplied by m, equal energy?

Dimensional analysis is your friend here.

dimensional analysis would be the same for speed of anything.

originally posted by: ErosA433

originally posted by: Nochzwei
the Einstein ring is wrongly named imo. this observation is due to time compression curves and not due to bending of space.
a reply to: Arbitrageur

Meaningless without... backup... provide theory in the language of mathematics and not in the language of buzzwords

equation of a circle. look it up

originally posted by: Nochzwei

originally posted by: Bedlam

originally posted by: ImaFungi
a reply to: Arbitrageur

Why does the value c², multiplied by m, equal energy?

Dimensional analysis is your friend here.

dimensional analysis would be the same for speed of anything.

But he'll understand why it equals energy.

a reply to: Bedlam

The concepts 'energy', 'mass', 'speed of light', and 'light' are all sketchy and controversial to at least some degree.

originally posted by: Nochzwei

originally posted by: ErosA433

originally posted by: Nochzwei
the Einstein ring is wrongly named imo. this observation is due to time compression curves and not due to bending of space.
a reply to: Arbitrageur

Meaningless without... backup... provide theory in the language of mathematics and not in the language of buzzwords

equation of a circle. look it up

*sigh*

oh yeah i see it now...





incorrect

a reply to: Bedlam

Dimensional analysis gives you something with units of energy (plausible candidate) but it doesn't give you physics or useful interpretable meaning.

For instance, spin of particles has the same units as Newtonian angular momentum. Is it actually angular momentum, or not? Dimensional analysis doesn't answer this.

The answer is 'yes, spin is real angular momentum': and that comes from the Einstein/DeHaas experiments and the like.

originally posted by: mbkennel
a reply to: Bedlam

Dimensional analysis gives you something with units of energy (plausible candidate) but it doesn't give you physics or useful interpretable meaning.

My take on fungi's question is 'why does this equal energy', and dimensional analysis will tell you 'because it does'.

Because the definition of energy IS that. I think that's what he was after, rather than 'why C and not the speed of an unladen swallow'.

originally posted by: ImaFungi
The concepts 'energy', 'mass', 'speed of light', and 'light' are all sketchy and controversial to at least some degree.

I don't really see much controversy in how these terms are communicated between physicists. For example even though the mass of a proton has a gluon field component composed of energy, we still define the mass of a proton using a specific method that as far as I know, is not controversial. I'm thinking controversial may not be the word you're looking for here.

originally posted by: Bedlam
Because the definition of energy IS that. I think that's what he was after, rather than 'why C and not the speed of an unladen swallow'.

It certainly IS that when accounting for the amount of mass converted to energy in solar fusion, so it's correct but not complete. If you've got something way faster than a swallow like protons at the LHC it's probably better to use this expression, where the mass term becomes relatively insignificant (over 7000 times smaller than the momentum term):

Is E=mc² right or wrong?


So dimensional analysis doesn't always give me the right answer, but it's always my friend, as it's useful in weeding out answers which are certainly wrong if the dimensional analysis fails.

originally posted by: Nochzwei
equation of a circle. look it up

originally posted by: ErosA433
incorrect

Yes it's obviously incorrect since a circle has two dimensional geometry and the formation of the Einstein-Chwolson ring is at least a three, and according to relativity, a four dimensional effect with time being the 4th dimension.

a reply to: Bedlam

The concept 'energy' requires 2 concepts;

Somethingness.

Movement.

The concept movement cannot exist, without 'something' which moves.

Theoretically, hypothetically, we can conceive, of the possibility of something existing, of something not moving.

What does the term 'energy' refer to, besides motion/movement?

The reason I am writing this post, is in reference to light being referred to as not only energy, but pure energy.

Such a statement would presume, that light is not somethingness, but movement itself. Which is a meaningless concept.

The concept of motion/movement, without 'something' that is undergoing the motion/movement is incorrect.

Energy is not 'a thing'. Motion is not 'a thing'.

Things exist. Things move. Thus, energy is the fact, things exist and things move. Energy is motion. What does the term energy refer to besides motion?

The only way I have thought so far, and it is not a clear thought with understanding but an attempt at imagining, how what I experience as a realness, of light, (to my senses, light appears to be something, rather than nothing) of how light may not be 'a thing' but 'pure movement' or pure energy;

Is that light itself, what is detected, experienced and utilized, is (and this is sloppy imagining, searching for an analogy), something like plate tectonic relative movements, the canyons that are made, the spaces that are made between them; That light would not be a something, but a 'crack' of sorts, amidst the network of somethings. Almost to say, light is a shadow. But this seems absurd. To try to think of how light itself might be 'nothing but motion'. And so I believe it is a sloppiness of terms, or arbitrariness which may lead to such difficulties in my understanding.

As I am trying to as close as possible, understand nature and how it operates, precisely, by the facts and truth of exactly what is and how.

so such classifications as, light is not matter, light is pure energy, etc. Are these classifications inherent in, of and as nature, or did people just tautologically make them up? I understand it is a system of weighing and balancing concepts, but there are problems in theoretical fundamental physics, and it is possible it is due to such neglect I am attempting to highlight, that such problems appear to linger and be problems at all.

a reply to: ImaFungi

E=Mc²

(according to what I have been declaring)

Motion = mass x c²

So the term and concept of 'energy', is a systematic attempt at studying and describing motion.

Light traveling a particular speed in vacuum, was significant concept, because it is believed to be an example of unwavering motion. Vacuum, implying generally no object to influence the path of light from a to b.

So energy relating to motion, of course if there was an ultimate rate of motion that would be significant, and such is thought of light.

It would be significant enough if it could be proven that a particular substance always moved at the same speed, but more so that a particular substance always moves at the same speed and that speed is the absolute fastest possible speed anything can move.

(I personally fail immediately, when considering the universe, physics, cosmology, because I cannot grasp how a massive quantity of entirely different fundamental types of particles can exist; and yet still I have heard it may be possible that they all may potentially be able to turn into each other. digress )

So the speed of light is, the amount of quadrants light moves in an amount of finger snaps, and mass is... I dont entirely know what mass is; but I would suggest that mass is the attempt to relatively quantify the 'inherent presence' of a particle. So some system of increments is developed in relation to how each particle interacts with a device which attempts to measure the inherent presence and assign it a number on the chart of increments of presence;

and for some reason, 'multiplying' (whatever that word means), that assigned number; to the assigned number of 'some relative ratio, rate, of light moving past increments related to how many increments it passes compared to how many finger snaps occur' (squared, whatever that means, and for whatever reason), equals; the rate of movement (energy) of the particles inherent presence (mass). boing.

originally posted by: ImaFungi
a reply to: Bedlam

The concept 'energy' requires 2 concepts;

Somethingness.

Movement.

The concept movement cannot exist, without 'something' which moves.

Theoretically, hypothetically, we can conceive, of the possibility of something existing, of something not moving.

What does the term 'energy' refer to, besides motion/movement?

The reason I am writing this post, is in reference to light being referred to as not only energy, but pure energy.

Such a statement would presume, that light is not somethingness, but movement itself. Which is a meaningless concept.

The concept of motion/movement, without 'something' that is undergoing the motion/movement is incorrect.

Energy is not 'a thing'. Motion is not 'a thing'.

Things exist. Things move. Thus, energy is the fact, things exist and things move. Energy is motion. What does the term energy refer to besides motion?

The only way I have thought so far, and it is not a clear thought with understanding but an attempt at imagining, how what I experience as a realness, of light, (to my senses, light appears to be something, rather than nothing) of how light may not be 'a thing' but 'pure movement' or pure energy;

Is that light itself, what is detected, experienced and utilized, is (and this is sloppy imagining, searching for an analogy), something like plate tectonic relative movements, the canyons that are made, the spaces that are made between them; That light would not be a something, but a 'crack' of sorts, amidst the network of somethings. Almost to say, light is a shadow. But this seems absurd. To try to think of how light itself might be 'nothing but motion'. And so I believe it is a sloppiness of terms, or arbitrariness which may lead to such difficulties in my understanding.

As I am trying to as close as possible, understand nature and how it operates, precisely, by the facts and truth of exactly what is and how.

so such classifications as, light is not matter, light is pure energy, etc. Are these classifications inherent in, of and as nature, or did people just tautologically make them up? I understand it is a system of weighing and balancing concepts, but there are problems in theoretical fundamental physics, and it is possible it is due to such neglect I am attempting to highlight, that such problems appear to linger and be problems at all.

Beyond the highschool definition on we all know of energy is something that produces work. Energy is something physics uses to calculate outcomes. I think fenyman put it best when he said it's a mathematical principle.

You have a real problem dealing with anything you can't see or touch. Your going to have to let go of what you believe to be reality and look at what the universe tells us. It's not all ways logical and often directly contradicts what we believe reality to be. But keep in mind out senses often perceive things wrong if they didn't magicians wouldn't exist. Here is a page that discusses all forms of energy.

electron6.phys.utk.edu...

originally posted by: ImaFungi
What does the term 'energy' refer to, besides motion/movement?

As I already said earlier in this thread any explanation of energy you get in a single post is likely to be at best, incomplete. Something can have potential energy without having any current movement, as this example from page 87 shows at the top of the hill, the motion is zero but it has potential energy.

originally posted by: Arbitrageur
Conservation of energy

Lower left you're moving say 20 miles an hour. When you're moving this is called kinetic energy. KE on the bar chart showing your energy.
Let's say the height of the hill is such that you'll make it to the top but almost stall completely there, so your speed goes to zero.

KE is zero at the top of the hill, where all your kinetic energy has been converted to potential energy, so if you look at the bar graph, it shows the same bar height at the bottom of the hill and at the top of the hill, but it's been completely converted from kinetic to potential energy (PE) at the top of the hill.

Energy is not 'a thing'. Motion is not 'a thing'.

According to my dictionary an idea can be a "thing" so I think you're not appreciating that the word "thing" has a very broad definition.

Things exist. Things move. Thus, energy is the fact, things exist and things move. Energy is motion. What does the term energy refer to besides motion?

See above example of potential energy with no motion.

so such classifications as, light is not matter, light is pure energy, etc. Are these classifications inherent in, of and as nature, or did people just tautologically make them up? I understand it is a system of weighing and balancing concepts, but there are problems in theoretical fundamental physics, and it is possible it is due to such neglect I am attempting to highlight, that such problems appear to linger and be problems at all.

Of course there are problems in theoretical fundamental physics, you just don't seem to know what they are probably because of your refusal to study this topic seriously by taking courses, reading textbooks, etc. The video by Sean Carroll in the opening post highlights a big problem, that we still don't know the correct interpretation of quantum mechanics. You could also review this list which doesn't mention any controversy about difficulties classifying light versus matter.

Of course all the man-made models are man-made and use terms defined by man, and are never perfect representations of reality, they are models.

originally posted by: Arbitrageur
As I already said earlier in this thread any explanation of energy you get in a single post is likely to be at best, incomplete. Something can have potential energy without having any current movement, as this example from page 87 shows at the top of the hill, the motion is zero but it has potential energy.

It still requires motion for anything to happen; if it was guaranteed that once the car thing was atop the hill, there was guaranteed to be no motion, there would be no potential energy, because it would be guaranteed that what one would think could be potential, would never occur. So potential energy in that case, is potential movement.

According to my dictionary an idea can be a "thing" so I think you're not appreciating that the word "thing" has a very broad definition.

An idea is 'a thing', or more appropriately or I should not, most 'a thing' is 'an intricate collection of things(atoms, molecules, photons). I dont see your point; an idea requires something existing, and for something that exists to move.

The most interesting case of 'energy', to me, though yes everything is interesting, is the mechanical potential energy, like a spring or winding; because does that not fundamentally come down to atoms binding strengths? That atoms can bind so strongly, to be torqued and twisted against another another and hold in place, storing their potential to move?

originally posted by: ImaFungi
So potential energy in that case, is potential movement.

Yes but there's a difference between potential movement, and movement.

I dont see your point; an idea requires something existing, and for something that exists to move.

The point should be obvious. You said "Energy is not 'a thing'." The dictionary says an idea is a thing. I fail to see how you can say an idea is a thing but energy is not a thing, what's the distinction? If a photon exists and it moves isn't it a thing according to your definition and if so why are you saying "Energy is not 'a thing', if a photon is a form of energy?

The most interesting case of 'energy', to me, though yes everything is interesting, is the mechanical potential energy, like a spring or winding; because does that not fundamentally come down to atoms binding strengths? That atoms can bind so strongly, to be torqued and twisted against another another and hold in place, storing their potential to move?

Yes, potential energy can also be stored in springs. Just as the car wants to fall or roll down the hill in the above example, the atoms in a compressed spring want to fall back down to a lower energy level where they are uncompressed, though the analogy only goes so far because it's a quantum mechanical effect unlike the car rolling down the hill.

originally posted by: Arbitrageur
Yes but there's a difference between potential movement, and movement.

In order for 'movement to occur', the potential for movement would 'have to occur'.

The difference is still = to movement. Take away the concept of movement completely, and there is no difference.

I agree that it is extraordinarily interesting, the fact that differing materials can be exerted against one another and attached to one another, in such a manner that the concept of potential energy (such as in a wound spring) can exist; 'possible movement contained currently in a lack of movement'. Mechanically how that lack of movement is contained is interesting. But ultimately still, the distinction is between 'objects' and their movements, and for reasons of their bodies physical relations, the ability to in scenarios have the potential to move, 'in a manner which would seem disproportional to the extent of just their physical body'.

The point should be obvious. You said "Energy is not 'a thing'." The dictionary says an idea is a thing. I fail to see how you can say an idea is a thing but energy is not a thing, what's the distinction? If a photon exists and it moves isn't it a thing according to your definition and if so why are you saying "Energy is not 'a thing', if a photon is a form of energy?

Ok this is a semantic misunderstanding. I used the term 'thing', in accordance to 'ultimate physical presence', as related to the terms 'something' and 'nothing'.

I can express my point by saying the following;

If only absolutely pure nothing existed; movement could not exist. In that sense, movement is not itself some physical thing. It is more that; Some physical thing is; and it moves or does not.

I used the term thing, to equate to a physical body, extension, substance, matter, presence.

I understand the tricky thing for me, is that energy/movement is conserved, it cannot be created or destroyed, which means it is just as fundamental as any thing.

Lets say all that existed surrounded by pure absolute nothing, was a single irreducible particle. lets say this particle was somehow, able to move.

According to the information I have provided in that thought experiment, no thing about the particle its bodied self would be changed, as you could say cutting an apple in half changes its physical body, or putting on clothes changes your physical body, or adding two lumps of clay together changes the original physical body, it is the same particle, undergoing 'movement'.

You were understanding the term thing, to mean any thing or concept the mind can think of, is labeled a thing, I was using it to only refer to exactly the physical presence that exists as reality/universe.

It is true, that the physical presence of the universe moves (seemingly).

And it is interesting, and a bit startling for me to think, how such movement, does have the great power of fundamentally altering the nature of the physical presence (such is chemical reaction); but movement is not 'a' physical thing, it is an aspect or characteristic of 'a physical thing/s'.

I do not know if this is a purely arbitrary semantical distinction I feel the need to make, or if there is an important fundamental meaning involved here.