Mass-Energy Equivalence
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04-05-2017, 06:00 AM
RE: Mass-Energy Equivalence
(03-05-2017 06:53 PM)Rahn127 Wrote:  This video will help a little.

Even though the video is short, I think I will have to watch it about ten times before I begin to understand it.

Here is my question: Doesn't a black hole demonstrate that energy isn't always conserved? Light falling into a black hole effectively disappears.
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04-05-2017, 06:19 AM
RE: Mass-Energy Equivalence
(04-05-2017 06:00 AM)Thoreauvian Wrote:  
(03-05-2017 06:53 PM)Rahn127 Wrote:  This video will help a little.

Even though the video is short, I think I will have to watch it about ten times before I begin to understand it.

Here is my question: Doesn't a black hole demonstrate that energy isn't always conserved? Light falling into a black hole effectively disappears.

Light (photons) are conserved, they just cant escape the black hole once they are beyond the event horizon. They just disappear from your view from outside of the event horizon. That you cant see them doesnt mean they dont exist anymore. They eventually fall into the singularity, like all mass falls into the singularity. Neither mass nor energy necessarily "disappears" (as in being annihilated) in the singularity. All energy and matter in a black hole is conserved. Hence the black hole still has a gravitaitonal field around it (because it still has mass, lots of mass).


The law of conservation of energy does (probably) not apply to the universe as a whole anyway, according to general relativity! (fallacy of composition i think)

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04-05-2017, 07:45 AM
RE: Mass-Energy Equivalence
(04-05-2017 06:19 AM)Deesse23 Wrote:  The law of conservation of energy does (probably) not apply to the universe as a whole anyway, according to general relativity! (fallacy of composition i think)

Can you expand on this statement? I don't get it. What in General Relativity might violate conservation of energy?
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04-05-2017, 08:39 AM
RE: Mass-Energy Equivalence
(04-05-2017 05:07 AM)houseofcantor Wrote:  Alternate facts, man. I've got all this mass and zero energy. Tongue

That must be rest mass. Consider

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04-05-2017, 08:42 AM
RE: Mass-Energy Equivalence
(04-05-2017 06:19 AM)Deesse23 Wrote:  
(04-05-2017 06:00 AM)Thoreauvian Wrote:  Doesn't a black hole demonstrate that energy isn't always conserved? Light falling into a black hole effectively disappears.

Light (photons) are conserved, they just cant escape the black hole once they are beyond the event horizon. They just disappear from your view from outside of the event horizon. That you cant see them doesnt mean they dont exist anymore.

I don't see how light could continue to exist without all of its properties. Light can't travel 186,000 miles per second in a singularity, and what does it become without even the room for its wave? You may say the energy is conserved, but in what possible form?
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04-05-2017, 08:50 AM
RE: Mass-Energy Equivalence
(04-05-2017 08:42 AM)Thoreauvian Wrote:  
(04-05-2017 06:19 AM)Deesse23 Wrote:  Light (photons) are conserved, they just cant escape the black hole once they are beyond the event horizon. They just disappear from your view from outside of the event horizon. That you cant see them doesnt mean they dont exist anymore.

I don't see how light could continue to exist without all of its properties. Light can't travel 186,000 miles per second in a singularity, and what does it become without even the room for its wave? You may say the energy is conserved, but in what possible form?

I'm not a physicist, but my understanding is that light is not necessarily confined to the singularity; it is only confined within the event horizon, which has a radius. So it presumably travels at 186,000 miles per second in some curved path which lies entirely inside the event horizon.
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04-05-2017, 09:04 AM
RE: Mass-Energy Equivalence
(04-05-2017 08:50 AM)Grasshopper Wrote:  
(04-05-2017 08:42 AM)Thoreauvian Wrote:  I don't see how light could continue to exist without all of its properties. Light can't travel 186,000 miles per second in a singularity, and what does it become without even the room for its wave? You may say the energy is conserved, but in what possible form?

I'm not a physicist, but my understanding is that light is not necessarily confined to the singularity; it is only confined within the event horizon, which has a radius. So it presumably travels at 186,000 miles per second in some curved path which lies entirely inside the event horizon.

This! Thumbsup
Light can travel around within the event horizon, but it cant leave it, going perpendicular to the horizon, since its (finite!) speed is too slow to overcome the gravitational field.

The answer to "what happens once it hits the singularity" is: We dont know. Relativity and quantum mechanics are giving different answers.

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04-05-2017, 09:20 AM (This post was last modified: 04-05-2017 09:26 AM by Deesse23.)
RE: Mass-Energy Equivalence
(04-05-2017 07:45 AM)John Derderian Wrote:  
(04-05-2017 06:19 AM)Deesse23 Wrote:  The law of conservation of energy does (probably) not apply to the universe as a whole anyway, according to general relativity! (fallacy of composition i think)

Can you expand on this statement? I don't get it. What in General Relativity might violate conservation of energy?

from the german wiki (paraphrasing):
Quote:Total energy is energy of resting mass plus kinetic energy, but for high energy particles measurements show this to be incorrect.....watching at the univese form a point of general relativity shows that conservation of energy can not be applied to the universe as a whole. Particularly gravitational energy can not be precisely defined, so that this is valid for the universe as a whole. Total energy of the universe is neither constant not inconstant, it can not be defined properly.
From: T. M. Davis: Verliert das Universum Energie? In: Spektrum der Wissenschaft. November 2010, ISSN 0170-2971, p. 23–29.

From the discussion of the wiki article (paraphrasing):
Quote:In general relativity, conservation of energy is valid only locally. Basically, gravitation also has energy in a certain sense. This energy however is always related to the system of reference, and locally you can transform gravtation always away. This means, locally, space within certain coordinates always looks like a Minkowski space (in which conservation does apply), but globally in gerneral it does not.

If i may add:
If it is true that vacuum energy of empty space exists, and is the main driving force of the accelerating universe then, by additional space "popping up out of nowhere", its energy is also added to the total energy of the universe. Ergo: with expanding space we have addition of energy to the universe, the total energy of the universe increases.
This of course contradicts the statement that the total energy of the universe may be zero.

To be honest, at this point this is going over my head. Blush

I guess the total and complete answer is: We dont know exactly yet, but have a few really nice ideas that currently dont really match each other. Work in progress. Angel

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04-05-2017, 12:20 PM
RE: Mass-Energy Equivalence
^^^ godidit

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04-05-2017, 05:19 PM
RE: Mass-Energy Equivalence
(04-05-2017 03:07 AM)Deesse23 Wrote:  That would be 90 million watts for 90 million seconds, or 90 megawatts for almost 3 Years!
Your car has like 90 kilowatts. So we could drive 1000 cars full speed 24/7 for 3 years with this single gram of mass converted into energy!
Releasing 90 trillion joules of energy in your gas tank would be . . . spectacular. Yes


Well, maybe not for you. Unsure

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