# The Naked Scientists Forum

### Author Topic: Would the photon lose all its energy at infinity?  (Read 69669 times)

#### JohnDuffield

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##### Re: Would the photon lose all its energy at infinity?
« Reply #125 on: 27/02/2015 14:36:12 »
Well, either you assume a different permittivity John, or you are proposing some to me unknown, not observer dependent mechanism?
The permittivity is different at a lower location. Only when you go there, you're different too, so the permittivity appears to be unchanged.

Because you are indeed telling me that light 'slows down'.
Yes, that's what Einstein said, repeatedly. Check out the Einstein digital archives, and search on speed of light or velocity of light.

If you're using another definition that whole post I reacted on was unnecessary. I saw Peter using time dilations to define it but in your case I still don't know what you use? And you're starting to come on as arrogant, which I find slightly surprising.
I meant to just give a straight answer that was factually correct and in line with Einstein and the evidence.

I don't mind people having pets, I have them too :) Writing "The permittivity and/or permeability of space at one elevation is not the same as at another." either seem to assume that there is one observer dependent redshift and another that solely belong to the 'photon' propagating, or that you still are thinking that all gravitational redshifts are outside observer dependencies?
I'm sorry, I'm not clear what you mean here. Please restate.

The last one makes a joke of any idea defining a photon as intrinsically being the same in a gravitational redshift, the first one is new to me, two mechanisms for a redshift, and I think it has to be proved.
We observe gravitational redshift, there's no issue in proving that. And IMHO conservation of energy says there shouldn't be any issue in proving that we observe it because we change. When you send a 511keV photon into a black hole, the black hole mass doesn't increase by a zillion tonnes. People say the descending photon is subject to an infinite blueshift, but its E=hf energy did not increase. But when you fall down, some of your mass-energy is converted into kinetic energy which is radiated away, leaving you with a mass deficit and less mass-energy. So the unchanged photon energy looks like it's increased.

The point is that you don't like different 'paths' as I gather?
Again, I'm not clear what you mean. If you're referring to the photon taking many paths, I'm totally happy with that. I've used the analogy of a seismic wave to for that.

#### yor_on

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##### Re: Would the photon lose all its energy at infinity?
« Reply #126 on: 27/02/2015 14:46:45 »
Actually the whole premise of propagation is just a pain in the ** to me John. Using a field as I think of it, one can avoid those questions. They belong to the container society.

#### yor_on

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##### Re: Would the photon lose all its energy at infinity?
« Reply #127 on: 27/02/2015 14:48:19 »
Try to read it as it stands. "Writing "The permittivity and/or permeability of space at one elevation is not the same as at another." either seem to assume that there is one observer dependent redshift and another that solely belong to the 'photon' propagating, or that you are thinking that all gravitational redshifts are outside observer dependencies?"

It's clear to me, what do you find unclear there?

Ignore 'still' btw, that was my fingers, not me :)
took it away as I saw it.
=

Let's use the full text btw, because it's the conclusions that make a difference there.

"Writing "The permittivity and/or permeability of space at one elevation is not the same as at another." either seem to assume that there is one observer dependent redshift and another that solely belong to the 'photon' propagating, or that you are thinking that all gravitational redshifts are outside observer dependencies?.

The last one makes a joke of any idea defining a photon as intrinsically being the same in a gravitational redshift, the first one is new to me, two mechanisms for a gravitational redshift, and I think it has to be proved."

« Last Edit: 27/02/2015 14:59:33 by yor_on »

#### yor_on

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##### Re: Would the photon lose all its energy at infinity?
« Reply #128 on: 27/02/2015 15:15:40 »
The observer dependent redshift belongs to the equivalence principle in my thoughts. With some translations it will define our earth as equivalent to a moving (constantly uniformly accelerating) spaceship at one constant gravity (ignoring spin). That's why I think of it as observer dependent although you measure this redshift being 'at rest' with Earth. I'm open for other interpretations though, but they need to fit what I understand to be relativity, or prove my toughts incorrect. It's actually easier to measure the blueshift thinking of it :) As you don't have to 'levitate', just stay on the ground, but the principle is complementary to measuring light leaving your spaceship, going in the 'opposite direction' (red shift, as defined from some inertial observer) as well as incoming light in the direction of your motion (giving you a blueshift) That's one of the things making Einstein the most awesome thinker I've read, he's so clear in his thinking. It's easy if one just give oneself some time to think it through (that's directed to all & Pete, we seem to share a similar taste there:)
=

So to summarize, if I'm correct gravitational redshifts is observer dependent, or the equivalence principle has to be changed in some way. If it is correct, then there is no way, that I know of, giving this principle (gravitational redshifts) two different mechanisms, one observer dependent the other belonging to some 'intrinsic principle' embedded in the photon solely.

thats one

Two

No way this is 'outside' observer dependencies. If it was then we can throw away GR. As far as I understands it.
=

and yes, it makes a 'photon' intrinsically the same, which is how I first read you John.
« Last Edit: 27/02/2015 16:00:34 by yor_on »

#### yor_on

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##### Re: Would the photon lose all its energy at infinity?
« Reply #129 on: 27/02/2015 16:31:55 »
Ok I think we've eliminated redshifts and their complementary time dilations from belonging to some 'intrinsic principle', but we have not eliminated a twin experiment. And it is not about a 'vacuum thickening its density' (permittivety), as far as I get it John?

A twin experiment is between two 'clocks', of a same origin, one accelerating to uniformly move away from that origin, to then return, finding one twins clock having been slower. Now, in my definitions this is a result of frames of reference interacting, but it is not a result of one clock ticking slower (or faster). Why I define it that way has to do with a lot of things, our definitions of repeatable experiments for one. observers in different uniform motions measuring each others clocks another, Also it has to do with you measuring, you won't ever find your clocks 'pace' to become 'slower' or 'faster', and your life span is the same, no matter what you do or how 'fast' you are. That one need a lot of reading up on to see how I think. But thinking that way, locality never change its 'pace', and that fit all experiments you can do, no matter NIST.

And it's not 'light paths', if I now remember you correct?
=

the easiest way to see how I mean is to accept the definition of 'c', then define it as valid for all circumstances instead of arguing that 'c' has different values due to mass and accelerations. And make it equivalent your local 'clock'. If I would want it otherwise, still setting 'c' to my local clock (arrow), I would be forced to define 'c' to different values, not only in accelerations (and mass), but also in uniform motions. And 'c' and your local arrow is the same, ideally and experimentally, prove me wrong.

The only way you can go around the last would be arguing that a acceleration is the sole instigator of a time dilation, making any ideas of 'muon experiments' wrong, as we already have defined what a gravitational red (as well as blue) shift is. They are observer dependent, and so depending on your frame of reference (Earth, or 'free falling' uniformly moving Muon in this case) A gravitational acceleration is a 'free fall', no 'forces' acting upon you locally defined, and I define it locally. As well as the logic of defining it soley to accelerations won't work.

This one is really easy to understand. Just jump out a plane without a parachute, and see the Earth rush to meet you. Because that is what you will feel, ignoring wind and atmosphere tugging on you. It's frames of reference and in Einsteins world the Earth is constantly uniformly accelerating, at one gravity.

that doesn't mean that accelerations and mass doesn't count, everything count, mass energy, accelerations, uniform motion. To me it all seems to have to do with frames of reference interacting.
« Last Edit: 27/02/2015 17:47:50 by yor_on »

#### yor_on

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##### Re: Would the photon lose all its energy at infinity?
« Reply #130 on: 28/02/2015 10:37:52 »
And that brings us to how to define a frame of reference, ideally, or from scaling. From scaling you could use some positional system, locally defined, Then try to see how that (it's still 'ideally' defined though in some sense) frame interacts with others, like NIST do in their experiments with different clocks at different locations. There is no way I see to define that local arrow I have to some (exact) position in a space and time though, as in 'there it is' :) And you will meet the same problem scaling, especially if the 'common clock' is created through interactions. That means that a 'ground beat' should exist, that's what makes repeatable experiments, and make us agree on a time for something, we being 'at rest' with, and in, some common frame of reference. But it also talks about the 'direction of time', locally measured, as something defined by those local interactions, interacting with each other on a larger scale, through 'c'. You could call it a bifurcation of Mach's principle, related to the common universe's experience of a global time, best described through our definitions of a Big Bang, applicable wherever you go in a 'infinite universe'. If we have a 'bit' then that should be the final arbiter of what a local position is, but to give it a 'time' you always will use your local clock.
=

what that state to me is that we always will be looking through tinted glasses defining a position, scaling. We have our ideal clock and ruler, locally invariant, and we all agree on it being equivalent. If we didn't repeatable experiments cease to exist. The real point is that they are equivalent, that is what have made physics. Now consider that through scaling, would you expect this to become untrue, scaling something down? The terms of how it interact may change, but I would expect this to hold true all the way down under.

What I, very tentatively, see such a reasoning doing, is giving us a local time (clock) equivalent to 'c', created through interactions in a 'commonly agreeable on universe'. That's one of the things making scaling so incredibly fascinating. You can't free yourself from your local clock and ruler though, so even if I would define a 'bit' as some smallest common nominator of 'time', as I use Planck scale for, you still would find 'time' to tick for you in that experiment, if you now could measure at that scale, which you can't. You can't prove it, because you can't free yourself from the universe you exist in, and making a experiment not using time is a very weird proposition. I would call it another reality myself, coexistent with the one we observe.
=

I would say that we have a lot of indirect proofs for it existing though. From the ideas of probabilities, to Feynman's sum over histories, to entanglements, to the ideas behind a quantum computer. That has very little to do with the idea of 'c'. But a lot to do with what may happen as you scale it down. The point to take home from such a reasoning is that the clock and ruler is you, and that everything you measure use it. Scaling doesn't change that fact, which is why it will be very hard, probably impossible, to design a experiment proving it. And you live 'in time', if time is consisting of 'bits' then what's between them won't exist for you, because that's where you are not.

Looking at it this way it is a geometry, a weird one, shaped through scaling, up into a macroscopic world where we live and 'observe'. Although I have a distinct feeling that algebra will describe it better than a geometric formulation, and that was the way I understand Einstein to have thought of it too. I think he was right.

( actually this last is about whether you want to define it locally or globally. Globally ( a 'common universe') Algebra should be your best choice. Locally I expect geometry to do just as good, possibly even clearer?. That's my opinion at least, well, for now :)
« Last Edit: 28/02/2015 16:19:53 by yor_on »

#### yor_on

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##### Re: Would the photon lose all its energy at infinity?
« Reply #131 on: 28/02/2015 14:01:05 »
If you define the way free fall act as a result of accelerations, then mass does not belong to it. Mass expresses itself not as 'accelerating', locally described. A real acceleration will give you a added feeling of weight added to you, whereas a gravitational acceleration gives you the opposite,  'weightlessness'. That 'weightlessness' is the exact same phenomena that describe a uniform motion. Einstein described it through different coordinate system, from a 'global point of view' as me standing on Earth, defining the 'free falling guy' to accelerate. From the point of view of that guy falling though, instead becoming the exact same as if he was uniformly moving through a space, weightless, in a geodesic. All of this locally defined.
=

We can turn it on its head by using one frame of reference, Earths. Then all gravitational accelerations belong to local accelerations as defined from some inertial point of view. now, is this right? Naaah, Einstein used locality, but also described it from the idea of a container. That's why we need different coordinate systems.
« Last Edit: 28/02/2015 15:13:42 by yor_on »

#### yor_on

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##### Re: Would the photon lose all its energy at infinity?
« Reply #132 on: 28/02/2015 14:05:59 »
The container demands you to use different coordinate systems. No way to describe this universe, not using frames of reference. But what then, is this idea of 'locality'? Well, in Einsteins reasoning you find a complementary description, as defined from the idea of something bigger, the common universe we live in. myself I stay locally anchored all the time. Because that is what defines us. I use frames of reference as he showed us, but I describe locality as what defines us. It has taken me a awful long time to express it, and that was what impressed me with Sachs (In Bills thread I think it was), that he too saw the same, a 'preferred frame', not in the mean of one frame of reference being more important, but from the aspect of the one considering yourself being the absolute best frame of reference, describing your experiences. And that's locality.

Once you realize that one, the only thing you need to do, is to take it to its extremes and see where it leads you.
=

Locally anchored, QM and relativity has a lot in common. Scaling is indeed about where a 'locality' ends, hoping to define it through quanta, or 'bits'. That is a good idea, as long as it in cooperates the other side of it, what comes before that quanta of 'motion', or 'time', or 'distance', or 'mass'. The other side don't use our arrow. Does that make you 'time less'? :) Nope, you're defined through a arrow and its outcomes, but what is 'you', is another question, that one belong to the exact same place as where we ask ourselves what 'thoughts' are? That's physics too (well to me it is:), but not one we can measure on. No way to measure that thought. The only thing we can measure on are those physical things that accompany it, but that's not the thought.

Yep, I see physics everywhere :)

And to my eyes, what stopped Einstein in his later years, and what made him argue against Entanglements and probability 'God does not play dice', was the way he thought of it, as a container. His work on a fifth dimension, unifying the universe, came from that exact position. He had the answer, but he wanted another. And that is what we all have John :) You and me, and all together. We have our pets.
« Last Edit: 28/02/2015 15:26:42 by yor_on »

#### jeffreyH

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##### Re: Would the photon lose all its energy at infinity?
« Reply #133 on: 28/02/2015 18:27:26 »
yor_on I agree with Pete that your posts do cause problems in reading a thread. Yet when I take the time to read through them, which I usually don't, you make some very interesting points. It is a shame that these get missed. I know you think an awful lot about this stuff. I just wish you posts were easier to read.

#### David Cooper

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##### Re: Would the photon lose all its energy at infinity?
« Reply #134 on: 28/02/2015 19:26:00 »
yor_on

It's streams of posts like this that make your writing useless. Almost nobody reads your posts because its like reading a book about nothing. It's a waste of our time so why do you do this? It makes everything else in the thread much harder to follow because you push other people's posts off the page into previous pages. Nobody wants to scroll through all this garbage to look for a small gem. Now please get with it.

Note: I know how selfish you are so I know that you're more interested in your own desires and less interested in everyone else's at our expense so I know that you don't care how we feel about it. Therefore when you try to justify your poor attitude you'll fail and just be wasting our time again.

+1 (with regard to the first paragraph)

Pete, you're picking fights all over. Believing that a expertise in one subject gives one reason to act rudely, or advertise ones own site as 'better', is a mistake on TNS. At least it used to be?  Actually I don't know any site that finds the last to be acceptable? I'm getting pretty tired reading your attacks now.

I think Pete's been pushed beyond a point where all the irritation which he's held back for many years is suddenly being unleashed in a great blast as he tells everyone straight what he thinks. (I'm mindreading, but I hope in a good way.) I'm sure it'll all come good in the end, but we all need to think more carefully about how we treat each other and how we come across.
« Last Edit: 28/02/2015 19:28:29 by David Cooper »

#### yor_on

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##### Re: Would the photon lose all its energy at infinity?
« Reply #135 on: 28/02/2015 19:31:29 »
You read the rules and then you either accept them, or you leave. Is that complicated David?

#### Ethos_

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##### Re: Would the photon lose all its energy at infinity?
« Reply #136 on: 28/02/2015 20:06:50 »
It saddens me to see these discussions turn into personal issues. I respect each and every member here that has something of interest to offer and especially those that I've become friends with.

One faithful member stated not long ago: "We should all be better than this."

And I applaud those who ascribe to that notion. Let's all work on this goal.

#### PmbPhy

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##### Re: Would the photon lose all its energy at infinity?
« Reply #137 on: 28/02/2015 20:47:25 »
Quote from: jeffreyH
Yet when I take the time to read through them, which I usually don't, you make some very interesting points. It is a shame that these get missed.
And that's one of the worst problems that he's causing. There's simply too much "filler" to want to wade through.
« Last Edit: 08/03/2015 05:38:19 by evan_au »

#### David Cooper

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##### Re: Would the photon lose all its energy at infinity?
« Reply #138 on: 28/02/2015 20:53:53 »
You read the rules and then you either accept them, or you leave. Is that complicated David?

Which rules are being broken? You are allowed to post long, rambling essays if you wish, and Pete's allowed to express annoyance with them, and to do so in a way that's rather stronger than might be socially acceptable. As for Pete's forum, it's trying to do something different which doesn't involve competing against this one, but to work as an addition to it so that disrupted conversations can be restarted in a more controlled space and better progress can be made with them. (I am involved in one such discussion there which has proved to be almost impossible to have on any other forum due to people who can't reason insisting on trying to derail it with a bombardment of illegal objections.) It is not designed to drag anyone away from here.

#### David Cooper

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##### Re: Would the photon lose all its energy at infinity?
« Reply #139 on: 28/02/2015 21:55:30 »
One useful trick would be for everyone to try to start from scratch in every thread, acting as if they have no negative history with anyone else who's taking part in them. That way, whenever war breaks out, it'll be easier to look back and find out what sparked it off.

#### jeffreyH

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##### Re: Would the photon lose all its energy at infinity?
« Reply #140 on: 28/02/2015 22:50:30 »
So is it a yes the photon does lose all its energy at infinity or a no?

#### PmbPhy

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##### Re: Would the photon lose all its energy at infinity?
« Reply #141 on: 28/02/2015 23:01:26 »
So is it a yes the photon does lose all its energy at infinity or a no?
No. Of course not. Where on earth did you get that idea anyway? The energy of a photon remains constant as it moves through a gravitational field.

#### PhysBang

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##### Re: Would the photon lose all its energy at infinity?
« Reply #142 on: 28/02/2015 23:13:04 »
Look what I have to keep dealing with.
I pointed out that I thought you were ignoring the very definition you were posting. It wasn't meant as an attack, just a point.

« Last Edit: 03/03/2015 10:55:16 by evan_au »

#### David Cooper

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##### Re: Would the photon lose all its energy at infinity?
« Reply #143 on: 28/02/2015 23:36:27 »
So is it a yes the photon does lose all its energy at infinity or a no?

Think about what happens with sound. There's someone plucking a string on a double bass at the bottom of a towerblock. You are able to watch and listen from the top of the towerblock, and you can hear that the note is flat. You go down in the lift and listen again, and it doesn't sound flat any more, so you go back up to the top and find that it's flat again. When you look down at the string from up there through a powerful telescope you can see it vibrating, and it appears to be vibrating exactly in sync with the sound you are hearing. You conclude from this that the sound has not reduced in frequency as it has climbed out of the gravity well, but that it is being generated at a lower frequency in the first place and it maintains that frequency all the way up as the sound climbs towards you. If it travels to infinity, the frequency will remain constant, but if you travel out to listen to it you will hear it as continuing to get more flat the further you get out of the gravity well. This reduction in the frequency you hear will become closer and closer to zero though (meaning the note doesn't appear to get much flatter at all) and the change will soon become impossible to measure - the strongest effect is deep down in the well, but once out in deep space you are in practical terms no longer in that well, even though you technically still are.

However, the frequency could still be reduced to zero over infinite distance because of dark energy and the expansion of space. It is this expansion that could decrease the energy of a photon infinitely, but not its journey out of a gravity well. [This then leads to other questions. Where then does that energy go to? Is the loss driven by the expansion of space, or do photons help to drive the expansion of space by throwing off some of their energy?]
« Last Edit: 28/02/2015 23:47:58 by David Cooper »

#### Russell Crawford

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##### Re: Would the photon lose all its energy at infinity?
« Reply #144 on: 01/03/2015 12:33:04 »
It would depend on the property of the photon that is in review. If one is speaking of the particle property or the wave property the answer would be different. This, of course, is all speculation. It there is in fact a particle property, then the photon could lose all its energy before "infinity", whereas if one is looking at it from a wave perspective, infinity can never be reached. There is no way to evaluate an infinite wavelength because its properties cannot be known.
That said if the wavelength could be infinite, the energy could, due to gravitational redshift, become increasingly smaller in an infinite sense.
I tend to believe that the particle property may be the best interpretation of the energy of a photon and that at some point it will have a "quanta" of energy that will be confirmed. But that is just an unfounded "belief".
With regard to "where the energy goes" it would seem to me (again a guess) that it would be lost over the distance from the source of the energy and the point at which it is measured. Perhaps trapped by gravity as planets are trapped and sorted?  Perhaps it could be called energy over distance or redshift potential energy. Again, that is speculation. I hope this answer will help people think about this important subject.
« Last Edit: 01/03/2015 15:46:55 by Russell Crawford »

#### yor_on

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##### Re: Would the photon lose all its energy at infinity?
« Reply #145 on: 01/03/2015 13:23:48 »
I'm sure it'll all come good in the end, but we all need to think more carefully about how we treat each other and how we come across.
You read the rules and then you either accept them, or you leave. Is that complicated?

Which rules are being broken? You are allowed to post long, rambling essays if you wish, and Pete's allowed to express annoyance with them, and to do so in a way that's rather stronger than might be socially acceptable. As for Pete's forum, it's trying to do something different which doesn't involve competing against this one, but to work as an addition to it so that disrupted conversations can be restarted in a more controlled space and better progress can be made with them. (I am involved in one such discussion there which has proved to be almost impossible to have on any other forum due to people who can't reason insisting on trying to derail it with a bombardment of illegal objections.) It is not designed to drag anyone away from here.

Well David. I'm sorry that it has come to this, and I actually Pm:ed Pete on the rules.
There are some rules concerning our behavior on this forum that we should try to follow. Keeping it friendly is one, another is about advertising ones own site. You can look it up or ask Pete. When it comes to writing long chunks :) Yep, got carried away there, it is as Jeffrey said, I think about it, then I see something I want to make better etc etc, ad infinitum. A dangerous thing, and one that shoot me in my ** here.

That doesn't mean that it excuses breaking other rules. It's in the end a Moderator decision whether to warn or not, so let us see what happens. If there is a lack of interest from the moderators point of view, I would suggest the rules to be rewritten though, so that they better fit the way this forum is going to act in the future.
==

(Well. What'da'ya'now :) pm's Internet slang for 'personal message' so it's ok any which way. Weird stuff)
« Last Edit: 03/03/2015 10:46:06 by evan_au »

#### yor_on

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##### Re: Would the photon lose all its energy at infinity?
« Reply #146 on: 01/03/2015 15:45:10 »
So is it a yes the photon does lose all its energy at infinity or a no?

Depends, and it goes back to how you define it. How does a accelerating expansion act on light? As a wave it's possible to understand, as a 'point-like photon' it's not. The only way I see it working is accepting a existing duality, in all circumstances. And that takes us once again, to a place of 'no propagation', exchanging it to excitations in a field. That is also a question of whether this duality becomes a macroscopic phenomena, quanta microscopically, or not?
=

that one is treating it 'practically' though. Theoretically I would guess no, it shouldn't lose its energy, unless we introduce this expansion acting on it. But all of this reasoning builds on you and me presuming a propagation. Exchanging that to excitations in a field it's no longer about 'unique photons propagating in a space' per se. To me it then seems to become more of a question of conservation laws. A propagation, or no propagation, that is the question :)
« Last Edit: 01/03/2015 15:59:11 by yor_on »

#### jccc

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##### Re: Would the photon lose all its energy at infinity?
« Reply #147 on: 01/03/2015 16:17:20 »
hope you guys don't mind, just my thought. i been learning from this thread.

is it possible that when atoms exited, they give off gravitational waves? like a bell knocked gives off vibrating energy?

#### yor_on

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##### Re: Would the photon lose all its energy at infinity?
« Reply #148 on: 01/03/2015 16:41:38 »
If I remember rightly Einstein had some thoughts on 'micro gravity' in the paper linked at http://physics.aps.org/story/v15/st11
Think it's called a 'Einstein-Rosen bridge' or nowadays 'wormhole'.

#### jeffreyH

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##### Re: Would the photon lose all its energy at infinity?
« Reply #149 on: 01/03/2015 16:49:54 »
So is it a yes the photon does lose all its energy at infinity or a no?

Think about what happens with sound. There's someone plucking a string on a double bass at the bottom of a towerblock. You are able to watch and listen from the top of the towerblock, and you can hear that the note is flat. You go down in the lift and listen again, and it doesn't sound flat any more, so you go back up to the top and find that it's flat again. When you look down at the string from up there through a powerful telescope you can see it vibrating, and it appears to be vibrating exactly in sync with the sound you are hearing. You conclude from this that the sound has not reduced in frequency as it has climbed out of the gravity well, but that it is being generated at a lower frequency in the first place and it maintains that frequency all the way up as the sound climbs towards you. If it travels to infinity, the frequency will remain constant, but if you travel out to listen to it you will hear it as continuing to get more flat the further you get out of the gravity well. This reduction in the frequency you hear will become closer and closer to zero though (meaning the note doesn't appear to get much flatter at all) and the change will soon become impossible to measure - the strongest effect is deep down in the well, but once out in deep space you are in practical terms no longer in that well, even though you technically still are.

However, the frequency could still be reduced to zero over infinite distance because of dark energy and the expansion of space. It is this expansion that could decrease the energy of a photon infinitely, but not its journey out of a gravity well. [This then leads to other questions. Where then does that energy go to? Is the loss driven by the expansion of space, or do photons help to drive the expansion of space by throwing off some of their energy?]

That's the sort of thing I was looking for. That sums up the situation exactly. It is unclear to many exactly what the true situation is. Thanks for this excellent post.

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##### Re: Would the photon lose all its energy at infinity?
« Reply #149 on: 01/03/2015 16:49:54 »