Gravity-temperature musings by Toffo

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Re: Gravity-temperature musings by Toffo

Postby Toffo » Fri Feb 19, 2016 12:03 pm UTC

Neil_Boekend wrote:
Toffo wrote:this causes the pizza to cool down

Why?


Because of some reason. Maybe time dilation.

Thermometer on the pizza does not measure any temperature change, because it time dilates, maybe.

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Re: Gravity-temperature musings by Toffo

Postby Neil_Boekend » Fri Feb 19, 2016 12:48 pm UTC

So it's a preset condition? There is something that cools it down, like a magical cooling beam? I'm not being sarcastic here, I just want to understand your experiment.
Then if and how much the pizza heats up when you winch it up depends on the properties of that magical cooling beam.

If it is not a preset condition then I think this may illuminate things:
Time dilation only cools down radiation (or heats it up) because the temperature of radiation is a resultant of it's frequency, or vibrations of the electromagnetic field per second. If you change the speed of seconds then the radiation temperature changes. Kinda, but not exactly, like the Doppler effect does on sound. The sound emitted by the speaker of a passing ambulance does not change as the ambulance passes, it just sounds that way because the ambulance changes from going towards you to going away from you.
So the pizza will not cool down due to time dilation. It will look like it's cooling down, because the radiation from the pizza gets stretched by the time dilation. It's not actually cooling, so if you winch it it will look like it is heating up again, but if you lift it back to the place where it was it'll have the same apparent temperature as it had before (assuming you do this fast enough to prevent radiation to heat it up while it is there). Simply because it did not actually cool down or heat up.
(Of course, this is a standing invitation to all people who know more of this than I do to check this and call me an idiot if it is wrong. Preferably with some information on where I went wrong, because I want to learn.)

The next part is significantly further beyond my knowledge, so before you take it as gospel please wait until someone with more knowledge of time dilation has looked at it.
Now if you were to lower a pizza towards a black hole the time dilation will "heat up" in falling cosmic background radiation. If you keep it there it will slowly assume thermal equilibrium with this heated cosmic background radiation. If you do this at a distance from the black hole where the time-delayed cosmic background radiation is at a temperature of 700K you could bake a perfect pizza. Raising it up out of the gravity well fast enough will get you a tasty pizza.
Where did this energy come from? That is a question I will leave to the actual experts on this forum.

One thing is for sure: This is the most expensive pizza baking oven I have ever heard of.

Damn. Now I want pizza. It doesn't have to be black hole baked, a normal one will do nicely.
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Re: Gravity-temperature musings by Toffo

Postby Toffo » Sat Feb 20, 2016 1:58 pm UTC

Neil_Boekend wrote:Time dilation only cools down radiation (or heats it up) because the temperature of radiation is a resultant of it's frequency, or vibrations of the electromagnetic field per second. If you change the speed of seconds then the radiation temperature changes. Kinda, but not exactly, like the Doppler effect does on sound. The sound emitted by the speaker of a passing ambulance does not change as the ambulance passes, it just sounds that way because the ambulance changes from going towards you to going away from you.
So the pizza will not cool down due to time dilation. It will look like it's cooling down, because the radiation from the pizza gets stretched by the time dilation. It's not actually cooling, so if you winch it it will look like it is heating up again, but if you lift it back to the place where it was it'll have the same apparent temperature as it had before (assuming you do this fast enough to prevent radiation to heat it up while it is there). Simply because it did not actually cool down or heat up.


(Of course, this is a standing invitation to all people who know more of this than I do to check this and call me an idiot if it is wrong. Preferably with some information on where I went wrong, because I want to learn.)

The next part is significantly further beyond my knowledge, so before you take it as gospel please wait until someone with more knowledge of time dilation has looked at it.
Now if you were to lower a pizza towards a black hole the time dilation will "heat up" in falling cosmic background radiation. If you keep it there it will slowly assume thermal equilibrium with this heated cosmic background radiation. If you do this at a distance from the black hole where the time-delayed cosmic background radiation is at a temperature of 700K you could bake a perfect pizza. Raising it up out of the gravity well fast enough will get you a tasty pizza.
Where did this energy come from? That is a question I will leave to the actual experts on this forum.



Nice analysis, I guess.

Now let's put our trusty old infrared thermometer at the center of a ring. The thermometer says the ring's temperature is 300 K. Then we start to spin the ring around faster and faster. The thermometer says the faster the speed of the ring, the lower the temperature of the ring.

So maybe this is a law: the faster a thing, the cooler the thing.

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Re: Gravity-temperature musings by Toffo

Postby Eebster the Great » Sat Feb 20, 2016 6:54 pm UTC

Toffo wrote:Now let's put our trusty old infrared thermometer at the center of a ring. The thermometer says the ring's temperature is 300 K. Then we start to spin the ring around faster and faster. The thermometer says the faster the speed of the ring, the lower the temperature of the ring.

So maybe this is a law: the faster a thing, the cooler the thing.


If the ring is circular and spinning on its axis and the thermometer is at the center, then every element of the ring is moving perpendicular to the radius and you don't even get a Doppler effect. Anyway, even when the radiation emitted by something cools due to e.g. cosmological redshift, that doesn't mean the radiating thing itself is cooled. Similarly, if I scream while running away from you, that doesn't mean my vocal cords have lengthened. It's just an effect of perception.

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Re: Gravity-temperature musings by Toffo

Postby gmalivuk » Sat Feb 20, 2016 8:01 pm UTC

Eebster the Great wrote:
Toffo wrote:Now let's put our trusty old infrared thermometer at the center of a ring. The thermometer says the ring's temperature is 300 K. Then we start to spin the ring around faster and faster. The thermometer says the faster the speed of the ring, the lower the temperature of the ring.

So maybe this is a law: the faster a thing, the cooler the thing.


If the ring is circular and spinning on its axis and the thermometer is at the center, then every element of the ring is moving perpendicular to the radius and you don't even get a Doppler effect. Anyway, even when the radiation emitted by something cools due to e.g. cosmological redshift, that doesn't mean the radiating thing itself is cooled. Similarly, if I scream while running away from you, that doesn't mean my vocal cords have lengthened. It's just an effect of perception.

Toffo isn't talking about doppler shift, but about time dilation.

The rest of your point still stands, though. The rest of the ring isn't "really" cooler any more than a ship traveling in a linear path at high velocity relative to you.
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Re: Gravity-temperature musings by Toffo

Postby Eebster the Great » Sat Feb 20, 2016 9:57 pm UTC

Oh I see, my mistake. So we're comparing the rotating reference frame of the ring to the inertial reference frame of the ring.

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Re: Gravity-temperature musings by Toffo

Postby Toffo » Sun Feb 21, 2016 11:59 pm UTC

Let's say we have a hot metal block in vacuum. It emits some electrons.

If the block moves fast, it still emits electrons, although it's cool now. From this we learn that fast moving objects have lowered boiling points, melting points, and so on.

Let's say we have a cool metal block in an electric field, not emitting electrons. If the block moves fast then it emits electrons, because, because of the motion, the temperature where the emission of electrons starts is lowered, which also means a quite weak electric field can rip off electrons.

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Re: Gravity-temperature musings by Toffo

Postby doogly » Mon Feb 22, 2016 12:57 am UTC

No, no no no, everything you have been saying is so wrong. Temperature does not work this way.
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Re: Gravity-temperature musings by Toffo

Postby Eebster the Great » Mon Feb 22, 2016 12:59 am UTC

Toffo wrote:Let's say we have a hot metal block in vacuum. It emits some electrons.

If the block moves fast, it still emits electrons, although it's cool now. From this we learn that fast moving objects have lowered boiling points, melting points, and so on.

Let's say we have a cool metal block in an electric field, not emitting electrons. If the block moves fast then it emits electrons, because, because of the motion, the temperature where the emission of electrons starts is lowered, which also means a quite weak electric field can rip off electrons.

Are you even reading our posts? Moving something does not make it colder.

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Re: Gravity-temperature musings by Toffo

Postby Toffo » Mon Feb 22, 2016 10:06 am UTC

Eebster the Great wrote:Are you even reading our posts? Moving something does not make it colder.


Yes some people say that moving something does not make it colder.

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Re: Gravity-temperature musings by Toffo

Postby Toffo » Mon Feb 22, 2016 10:16 am UTC

Toffo wrote:Let's say we have a hot metal block in vacuum. It emits some electrons.

If the block moves fast, it still emits electrons, although it's cool now. From this we learn that fast moving objects have lowered boiling points, melting points, and so on.

Let's say we have a cool metal block in an electric field, not emitting electrons. If the block moves fast then it emits electrons, because, because of the motion, the temperature where the emission of electrons starts is lowered, which also means a quite weak electric field can rip off electrons.


Some people might say the electrons were ripped off because the fast motion caused a repulsive magnetic force between protons and electrons.

But I don't.

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Re: Gravity-temperature musings by Toffo

Postby eSOANEM » Mon Feb 22, 2016 11:24 am UTC

Toffo wrote:
Eebster the Great wrote:Are you even reading our posts? Moving something does not make it colder.


Yes some people everyone who knows what they're talking about says that moving something does not make it colder.


ftfy

Seriously, you are just making shit up and not listening to any arguments as to why you're wrong.
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Re: Gravity-temperature musings by Toffo

Postby Eebster the Great » Mon Feb 22, 2016 4:46 pm UTC

Toffo wrote:Some people might say the electrons were ripped off because the fast motion caused a repulsive magnetic force between protons and electrons.

Nobody would say that because you literally stated in the description of the scenario that it's thermionic emission.

Let me put this another way. The central idea of special relativity is that the laws of physics do not depend on your reference frame. You cannot tell if you are in motion because even if you move from one reference frame to another (by some brief acceleration), nothing will fundamentally change, like the speed of light or the fine structure constant. However, in your description, I need only run faster and I will start to mysteriously cool down, yet sweat will continue to evaporate as if I were warm. That is certainly a change in physics.

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Re: Gravity-temperature musings by Toffo

Postby Toffo » Tue Feb 23, 2016 9:59 am UTC

Eebster the Great wrote:Let me put this another way. The central idea of special relativity is that the laws of physics do not depend on your reference frame. You cannot tell if you are in motion because even if you move from one reference frame to another (by some brief acceleration), nothing will fundamentally change, like the speed of light or the fine structure constant. However, in your description, I need only run faster and I will start to mysteriously cool down, yet sweat will continue to evaporate as if I were warm. That is certainly a change in physics.



When you move, you don't know you move. When you are cool, you don't know you are cool.

If you don't understand, then you don't understand.

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Re: Gravity-temperature musings by Toffo

Postby Neil_Boekend » Tue Feb 23, 2016 11:26 am UTC

Toffo wrote:When you move, you don't know you move.
In a way true, based in general relativity. You can only measure difference in speed, for example relative to the earth's surface. There is not such a thing as absolute speed. Only speed difference between two objects.
When you are cool, you don't know you are cool.
Untrue. You can measure your absolute temperature, by means of contact thermometers.This allows you to know if you are cool.
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Re: Gravity-temperature musings by Toffo

Postby Toffo » Tue Feb 23, 2016 11:03 pm UTC

I created this play to enlighten you all:

The story about a Moving Guy and a Standing Guy

Standing Guy to Moving Guy: Hey Moving Guy, are you moving?

Moving Guy: No.

Standing Guy to Moving Guy: Hey Moving Guy, are you cold?

Moving Guy: No, because I am not moving.

Standing Guy to himself: Moving Guy does not know he is moving, and Moving Guy does not know he is cold.

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Re: Gravity-temperature musings by Toffo

Postby Sizik » Tue Feb 23, 2016 11:36 pm UTC

Give Moving Guy a glass of water. Is there a speed at which the water will freeze?
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Re: Gravity-temperature musings by Toffo

Postby Eebster the Great » Wed Feb 24, 2016 12:20 am UTC

Yes, I get the notion that we can imagine any property to be relative if we don't understand how physics works. Consider this comparable exchange:

Spoiler:
Standing Guy to Moving Guy: Hey Moving Guy, are you moving?

Moving Guy: No.

Standing Guy to Moving Guy: Hey Moving Guy, are you an arachnid?

Moving Guy: No, because I am not moving.

Standing Guy to himself: Moving Guy does not know he is moving, and Moving Guy does not know he is an arachnid.


Does that sound absurd? Of course it does, because there are objective ways to tell if you are an arachnid that do not depend on your speed. For instance, if you do not have eight legs, you are probably not an arachnid. Similarly, there are objective ways to tell if you are cold. For instance, if your blood is boiling, you are probably not cold. This is true regardless of your speed.

The whole point of special relativity, once again, is that the laws of physics _do not depend_ on your reference frame. You trying to make them depend on the reference frame only demonstrates your misunderstandings, not Einstein's.

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Re: Gravity-temperature musings by Toffo

Postby Toffo » Fri Feb 26, 2016 8:39 pm UTC

Let's consider a warm black box. Interestingly, when this black box moves fast, it contains more radiation compared to a still standing box, because the moving box is contracted (less room for photons), but the photon gas is contracted more (more photons fit into the box).

I'm referring to the blue shifted photons with their length contracted wave lengths, and also the length contracted distance between said photons.

Hm so maybe the walls contain less heat energy because the heat energy became radiation when the box was accelerated to great speed.

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Re: Gravity-temperature musings by Toffo

Postby Copper Bezel » Fri Feb 26, 2016 10:40 pm UTC

Are you reading anything anyone else is posting? Appending "let's say that [additional wrong thing]" to a wrong statement is not an improvement.
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Re: Gravity-temperature musings by Toffo

Postby gmalivuk » Fri Feb 26, 2016 11:02 pm UTC

Toffo wrote:the moving box is contracted (less room for photons), but the photon gas is contracted more (more photons fit into the box).
Why would the photon gas contract more, and not by exactly the same amount?
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Re: Gravity-temperature musings by Toffo

Postby Toffo » Fri Feb 26, 2016 11:20 pm UTC

Copper Bezel wrote:Are you reading anything anyone else is posting? Appending "let's say that [additional wrong thing]" to a wrong statement is not an improvement.


Everything read and understood. :D
Last edited by Toffo on Mon Feb 29, 2016 2:19 am UTC, edited 2 times in total.

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Re: Gravity-temperature musings by Toffo

Postby Toffo » Fri Feb 26, 2016 11:30 pm UTC

gmalivuk wrote:
Toffo wrote:the moving box is contracted (less room for photons), but the photon gas is contracted more (more photons fit into the box).
Why would the photon gas contract more, and not by exactly the same amount?



Good question. In the fast moving box there are blueshifted photons and redshifted photons, blueshifted photons are packed tightly as the wall emitting these photons is moving almost at the same speed as the photons are moving.

I like to think blueshift as length contraction.

The redshifted photons we just ignore at the moment.

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Re: Gravity-temperature musings by Toffo

Postby gmalivuk » Fri Feb 26, 2016 11:46 pm UTC

Oh well sure, if you ignore the ones that are redshifted, then you end up with a bluer shift on average. Just like how if I ignore everyone making less than $100k per year, average income skyrockets!
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Re: Gravity-temperature musings by Toffo

Postby doogly » Sat Feb 27, 2016 12:53 am UTC

Toffo wrote:
Copper Bezel wrote:Are you reading anything anyone else is posting? Appending "let's say that [additional wrong thing]" to a wrong statement is not an improvement.


Everything read and understood. :D

You should not make the big smiley face, because you have painted yourself back into a corner where you are reaching a conclusion which you have been repeatedly told is wrong. You seem eager and delighted to find ever new ways to be wrong. Why is this? This is trouble.
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Re: Gravity-temperature musings by Toffo

Postby Eebster the Great » Sat Feb 27, 2016 5:11 am UTC

Finding new ways to be wrong would be preferable to obstinately repeating the same wrong claim "supported" by thought experiments that beg the question. Errasse humanum est, sed in errare perseverare diabolicum.

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Re: Gravity-temperature musings by Toffo

Postby Toffo » Sun Feb 28, 2016 3:18 am UTC

Does the composition of a body depend on its speed?

Let's say there's a box far from all masses. There are two scientists, A and B, with clocks at the opposite ends of the box, inside the box. Every second A sends a photon towards B, and every second B absorbs a photon that was emitted by A.

Now we turn on a gravity field, which will slow down clock B more than clock A.

The box is free falling so scientist do not notice any difference.

But an observer that is hovering instead of falling sees something like this:

Every two seconds of the hovering observers time A sends a photon towards B, and every three seconds of the hovering observers time B absorbs a photon that was emitted by A, and the number of photons in the box is increasing with time according to the hovering observer.

If the roles of A and B were reversed, then the number of photons in the box would be decreasing.

Let's say there's another box identical to the first one, but turned around 180 degrees. This box is a one in which number of photons starts to decrease when the gravity is turned on.

Now we imagine a large box around those two boxes. The number of photons inside the large box approaches infinity, as the number of photons in one smaller box approaches infinity, and the number of photons in the other smaller box approaches zero.

Conclusion: An increase of speed of a body increases the amount of radiation inside the body.

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Re: Gravity-temperature musings by Toffo

Postby Copper Bezel » Sun Feb 28, 2016 5:51 am UTC

Well, to start at a very basic level ... first, your whole model depends on the idea that the effect of the gravity well is nonuniform along the shaft of the experiment, since different points are at different gravitational potentials; that's the only reason the two ends differ and is also not applicable if the experiment is being uniformly accelerated instead. Second, you've been talking about things "moving very fast" until now (which is pretty ambiguous without specifying a reference frame and whatnot - a simple difference in velocity also has symmetrical effects) while a gravity well is an actual constant acceleration, not a mere relative difference in velocity between two observers.
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Re: Gravity-temperature musings by Toffo

Postby Eebster the Great » Sun Feb 28, 2016 6:13 am UTC

Acceleration certainly does affect the energy content and temperature of anything, even a vacuum in the case of Unruh radiation. But I don't know specifically about that thought experiment.

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Re: Gravity-temperature musings by Toffo

Postby gmalivuk » Sun Feb 28, 2016 6:40 am UTC

Wouldn't Unruh radiation mean it's false to assume the only photons in the box are the ones emitted directly by A and B?

In which case the rest of Toffo's thought experiment no longer follows.
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Re: Gravity-temperature musings by Toffo

Postby Eebster the Great » Sun Feb 28, 2016 7:44 am UTC

Right that effect wouldn't produce the results Toffo is claiming, which is why I said I don't know about that specific experiment. I haven't thought about it deeply enough to even tell if I know enough to answer it. But my point is that if we are taking acceleration or gravity into account, we are definitely going to be changing the temperature regardless of that specific idea.

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Re: Gravity-temperature musings by Toffo

Postby Copper Bezel » Sun Feb 28, 2016 1:12 pm UTC

Oh, true point, you're right, the effects of acceleration wouldn't be symmetrical like I said. It does need to be acceleration rather than the ambiguous "moving really fast", obviously, but.
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Re: Gravity-temperature musings by Toffo

Postby Toffo » Mon Feb 29, 2016 2:14 am UTC

Hey I changed my mind. :) When a box that is already moving fast is accelerated, the blue shifted photons emitted by the box blue shift more, and the contracted box contracts more, and the magnitudes of these effects are almost equal.

So there's no room for ridiculous number of length contracted photons in the length contracted box.

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Re: Gravity-temperature musings by Toffo

Postby Toffo » Thu Mar 17, 2016 4:55 am UTC

Now I would like to consider energy, again.

So when an object is lifted, by a lifter that uses energy E, the energy of the object increases by E. This is quite believable.

When an object is lifted, increasing its energy by E, the energy of the planet, from which the object is lifted, increases by E. This is quite clearly required to avoid ugly asymmetry.

So the obvious lifter is providing 50% of the total energy needed to lift, and some non-obvious lifter provides the other 50%.

OK now, if I may suggest, the experts may start protesting, and the non-experts may start giving suggestions what might be the "non-obvious lifter". :)

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Re: Gravity-temperature musings by Toffo

Postby Eebster the Great » Thu Mar 17, 2016 7:46 am UTC

Toffo wrote:When an object is lifted, increasing its energy by E, the energy of the planet, from which the object is lifted, increases by E. This is quite clearly required to avoid ugly asymmetry.

I can't even

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Re: Gravity-temperature musings by Toffo

Postby Toffo » Thu Mar 17, 2016 9:16 am UTC

Eebster the Great wrote:
Toffo wrote:When an object is lifted, increasing its energy by E, the energy of the planet, from which the object is lifted, increases by E. This is quite clearly required to avoid ugly asymmetry.

I can't even



That is not even the odd part, when two objects want to be close to each other and we move the objects away from each other, then both gain energy symmetrically.

But there seems to be a mysterious energy/force/whatever that wants the two objects to be away from each other.

Hm one Joule of light weighs twice as much as one Joule of matter, right? So light does not feel the mystery force, while matter does feel it.

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Re: Gravity-temperature musings by Toffo

Postby Neil_Boekend » Thu Mar 17, 2016 11:17 am UTC

Toffo wrote:OK now, if I may suggest, the experts may start protesting, and the non-experts may start giving suggestions what might be the "non-obvious lifter". :)

It depends on what the reaction mass is.
  • If you lift an object by hand, your feet push the earth down. The center of gravity of the system you + box + earth does not move.
  • If you lift an object by means of rockets and the reaction mass does not go to the earth's atmosphere then the earth does not move (initially). The center of gravity of you + box + rocket exhaust + earth does not move.
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Re: Gravity-temperature musings by Toffo

Postby gmalivuk » Thu Mar 17, 2016 11:46 am UTC

Toffo wrote:When an object is lifted, increasing its energy by E, the energy of the planet, from which the object is lifted, increases by E. This is quite clearly required to avoid ugly asymmetry.
What ugly asymmetry?
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Re: Gravity-temperature musings by Toffo

Postby Toffo » Fri Mar 18, 2016 10:50 am UTC

gmalivuk wrote:
Toffo wrote:When an object is lifted, increasing its energy by E, the energy of the planet, from which the object is lifted, increases by E. This is quite clearly required to avoid ugly asymmetry.
What ugly asymmetry?



I want both gravitating objects to equally gain energy when a lifting process is happening. By equally I mean same number of gained joules, not same percentage.

Let's see now ... When matter accumulates, space sucks energy out of the matter. And when matter disperses, space gives back the energy that it sucked out of the matter when the matter coalesced. Anybody have any problem with this?

Toffo
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Re: Gravity-temperature musings by Toffo

Postby Toffo » Fri Mar 18, 2016 11:03 am UTC

Neil_Boekend wrote:
Toffo wrote:OK now, if I may suggest, the experts may start protesting, and the non-experts may start giving suggestions what might be the "non-obvious lifter". :)

It depends on what the reaction mass is.
  • If you lift an object by hand, your feet push the earth down. The center of gravity of the system you + box + earth does not move.
  • If you lift an object by means of rockets and the reaction mass does not go to the earth's atmosphere then the earth does not move (initially). The center of gravity of you + box + rocket exhaust + earth does not move.


Let's just lift slowly enough, and let's ignore kinetic energy.


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