Photons and conservation momentum (split from Pioneer anomaly)

[Bjarne]

Momentum of electromagnetic radiation is the correct question.

How can radiation from the space probe towards empty space possible have a decelerating impact on the pioneer space probes.

Are there any scientific evidence for such statement ?

It sounds acceptable that the opposite, - which mean photon bombarding / hidding the space probe - could have an effect, and either accelerate of decelerate the space probe.

But photons leaving the space probe? - no, - unless there are hard evidence, - such is really difficult to believe.

Edited December 1, 2014 by Bjarne

[Strange]

Momentum of electromagnetic radiation is the correct question.

How can radiation from the space probe towards empty space possible have a decelerating impact on the pioneer space probes.

 

Conservation of momentum: sending radiation in one direction causes a force in the opposite direction.

http://en.wikipedia.org/wiki/Radiation_pressure#Radiation_pressure_by_emission

 

Note that a solar sail gets "push" from two sources: first by being hit by photons and then by reflecting the photons. The latter is exactly what you are asking about.

 

Why do you emphasize "towards empty space"? Why would that matter?

Edited December 1, 2014 by Strange

[Bjarne]

 

Conservation of momentum: sending radiation in one direction causes a force in the opposite direction.

http://en.wikipedia.org/wiki/Radiation_pressure#Radiation_pressure_by_emission

 

Note that a solar sail gets "push" from two sources: first by being hit by photons and then by reflecting the photons. The latter is exactly what you are asking about.

 

Why do you emphasize "towards empty space"? Why would that matter?

 

So to explain the Pioneer Anomaly, only photons hitting hte antenna, should be enought to come to that result as Anderson and his team did ?

[Strange]

 

So to explain the Pioneer Anomaly, only photons hitting hte antenna, should be enought to come to that result as Anderson and his team did ?

 

Huh? No, the largest effect (beyond some distance) is the radiated energy. They do also take solar radiation into account (which is, again, mainly the heating effect increasing radiation, as far as I remember - I haven't read the paper in a long time and I don't have time to go through it again now - but I was immensely impressed by the level of detail they put into modelling the various surface features, sources of energy, etc.)

Momentum of electromagnetic radiation is the correct question.

How can radiation from the space probe towards empty space possible have a decelerating impact on the pioneer space probes.

 

By the way, if the momentum change caused by radiated photons wasn't equal and opposite to the momentum change caused by received photons, then you could build a free energy machine: a box with a light source at one end and an absorbing screen at the other. If your doubts were correct then there would be no force from the photons emitted but only from those received, resulting in a net force with no external release of energy....

[Bjarne]

Photons emitted or received have the same effect. This is necessary for momentum conservation: light carries some momentum opposite to the emitter's recoil, and transfers it to the target. Other interpretations wouldn't conserve the sum of momentums of the emitter plus the light, the light plus the target, or the emitter plus the target.

Agree

 

Even better than a theory or a principle, the momentum of light is observed at spacecraft, with an interesting accuracy. Both received and emitted light, both visible and far infrared. At geosynchronous satellites, radiation pressure uses to be the main external torque, parasitic or useful since many satellites use it to stabilize themselves.

 

Can you expain more in details

Has it ever really been demonstrated that photons emitted (from a spacecraft) towards a certian direction (towards empty space) really, - really can move a space craft the oppesite direction?

Do you have a source I can read ?

 

(Or are you only talking bout evidence that shows that impact of photon bombardment / absorbed photons can convert to kenetic enrgy, and thereby move a space craft. ?)

 

Radiation coming from outside the Solar system isn't probable.

First, it would need a significant strength to explain the Pioneer anomaly, but we observe radiation at so many wavelengths without noticing that. The anomaly gets significant as compared to our Sun's radiation pressure near Saturn's orbit, where sunlight is still stronger than any lamp.

 

Then, both Pioneers observed the same deceleration (one craft more accurately than the other) despite going to different directions after the Saturn flyby. That makes an explanation by unidirectional radiation more difficult. But if isotropic, radiation towards the Sun would re-emerge at the opposite site, cancelling the effect out - unless it stops at the Sun.

 

In his latest opinion:

"Support for the thermal origin of the Pioneer anomaly", arXiv 1204.2507

Anderson claims (and I don't agree) that 45% of the anomaly is recoil from heat emitted by the equipment, 35% heat emitted asymmetrically by the generators without influence by the antenna, and 20% due to propagation or being within the uncertainties.

 

One basic difference (besides detail arguments) is that I checked if the speed curve could be fit by radiation recoil, while Anderson made a fit on the acceleration curve. The acceleration curve is more tolerant, because it accepts misfits always in the same direction within the uncertainty, while these small misfits accumulate on the speed curve to make it impossible to fit. The curvatures differ, see message #4.

 

So I dont' tell "Turyshev's model is wrong" (I have discrepancies with some paint degradations; things like that) but rather "the model doesn't pass a more stringent test".

 

So how much do you think radiation can account for ?

 

I wonder about .... how can we be sure that emitting photons possible should have the same effect as a recoil from a gun.

I mean there is no logical recoil connected to photons emitted from a nuclear explosion etc...

What happens with that 'recoil-energy' if the radiation is isotropoic ?

 

Maybe I have no reason to be sceptical, if so please convience me..

 

Huh? No, the largest effect (beyond some distance) is the radiated energy. They do also take solar radiation into account (which is, again, mainly the heating effect increasing radiation, as far as I remember - I haven't read the paper in a long time and I don't have time to go through it again now - but I was immensely impressed by the level of detail they put into modelling the various surface features, sources of energy, etc.)

 

By the way, if the momentum change caused by radiated photons wasn't equal and opposite to the momentum change caused by received photons, then you could build a free energy machine: a box with a light source at one end and an absorbing screen at the other. If your doubts were correct then there would be no force from the photons emitted but only from those received, resulting in a net force with no external release of energy....

 

I am not sure you can use classis Newtonian physics. Emitting photon energy is released from a nuclear a quantum process (so fare I understand) a process we maybe not fully have understood. I mean we even don’t know what a photon really is, it have no known physical structure and is massless, and even time and distance should exist from its own view point.. I think we have to be carefully to connect it with classic properties, unless there is sufficient evidence

[Strange]

Can you expain more in details

Has it ever really been demonstrated that photons emitted (from a spacecraft) towards a certian direction (towards empty space) really, - really can move a space craft the oppesite direction?

Do you have a source I can read ?

 

http://en.wikipedia.org/wiki/Radiation_pressure#Radiation_pressure_by_emission

 

A solar sail produces twice as much force when it reflects photons:

 

perfect absorbance: F = 4.54 μN per square metre (4.54 μPa)

perfect reflectance: F = 9.08 μN per square metre (9.08 μPa) (normal to surface)

http://en.wikipedia.org/wiki/Solar_sail#Physical_principles

 

And, as noted, if emitting photons violated conservation of momentum then it would be possible (trivially easy) to build a reactionless drive and build a free-energy source. It isn't.

 

Also, can you explain why you say "towards empty space" as if that were significant?

 

 

I am not sure you can use classis Newtonian physics.

 

Of course you can: conservation of momentum.

[Bjarne]

 

Earth receives energy approximately [math]1360 \frac{J}{s*m^2}[/math] (without counting loses caused by atmosphere).

Distance 1 AU = 149,600,000,000 m

 

Reversing inverse-square law gives energy emitted by Sun per second:

[math] 1360 * 4 * \pi * 149600000000 ^2 = 3.825*10^{26} W[/math] (wiki mentions 3.846*10^26, so we're pretty close).

 

Now if we will calculate energy at distance 40.4 AU = 6,043,840,000,000 m

[math]\frac{3.825*10^{26}}{4*\pi*6,043,840,000,000^2}=0.833251642 \frac{W}{m^2}[/math]

 

5.2 W/m^2 is 2 * PI bigger than 0.8333 W/m^2..

 

5.2 W/m^2 is at distance 16.16 AU from the Sun.

 

Please also notice it's easy to make mistake by calculating distance satellite traveled from Earth 40.4 AU, instead of from the Sun (not saying it's in this case because I didn't verified data).

So how much will the Earth be affected on yearly basis ?

9.08 µPa (µN/m²)

 

http://en.wikipedia.org/wiki/Radiation_pressure#Radiation_pressure_by_emission

 

A solar sail produces twice as much force when it reflects photons:

http://en.wikipedia.org/wiki/Solar_sail#Physical_principles

 

And, as noted, if emitting photons violated conservation of momentum then it would be possible (trivially easy) to build a reactionless drive and build a free-energy source. It isn't.

 

Also, can you explain why you say "towards empty space" as if that were significant?

 

 

Of course you can: conservation of momentum.

 

I understand that we have mathematical ‘evidence’..

 

But does any objective evidence for instant experimental or experience really support both phenomena?

That radiation really can convert to kinetic energy,…

 

a.) by hitting / being absorbed by an objet

b.) emitting radiation - from and object

 

1. Satellite navigation was mentioned in a post above, - how excactly does that happen ? by radiation ? absorbation ? or ?
2. Solar sails was mentioned, - are such allready tested, or is this so far only theory?
3. Other objective facts ?

I really like to read more about this and would appreciate some links to objective facts, and not only mathematical ‘facts’

Edited December 2, 2014 by Bjarne

[Sensei]

See Crookes radiometer

http://en.wikipedia.org/wiki/Crookes_radiometer

[Strange]

But does any objective evidence for instant experimental or experience really support both phenomena?

 

You are the one challenging the most fundamental aspects of physics, it is up to YOU to provide evidence to support your claims of magic occurring.

 

But... SOLAR SAILS. Sheesh.

See Crookes radiometer

http://en.wikipedia.org/wiki/Crookes_radiometer

 

No, don't. That is nothing to do with it. But you could look at the Nichols radiometer.

http://en.wikipedia.org/wiki/Nichols_radiometer

Edited December 2, 2014 by Strange

[Bjarne]

 

You are the one challenging the most fundamental aspects of physics, it is up to YOU to provide evidence to support your claims of magic occurring.

 

On the one hand, yes I know that words (or mathematic) is not enough.

The scientific method must be passed, before something can be said to be “certain knowledge”

 

On the other hand, much of what we today call science, has never passed any scientific method, but anyway presented like, - certain knowledge.

Also the discussion we have here, is hard for me to see really have passed the any scientific method.

As I so fare see it, - it is only a mathematically based speculation (?)

Unless hard evidence really can be presented (which unfortunately, doesn’t seems to be the case) - I (at least) will remain sceptic until then. ..

 

New observation is constantly bombarding us.

Still more and more knowledge that too many times, -.simply cannot adapt to our (narrow) picture of the Universe.

Every time (for instant) we discover a new orbit anomaly (and there are plenty) we try to find a speculative new theory for each single of these.

The pioneer anomaly is only one of many “case closed” histories, - that who knows, - in reality maybe means “eyes closed”.

 

When it comes to huge galaxy and cluster orbit anomalies, we need more and more speculation builds on the top of each other, to be able to keep the old already wobbling paradigm alive.

And again it is certain knowledge that it really is dark matter out there, and no other possibilities.

 

It seems almost that it is not allowed to look for a possible common denominator that could have been overlooked, if this means that (too) must have to be thrown overboard.

Maybe because too many will get red ears if such possible can succeed.

 

One should not throw stones if one lives in a glass house.

 

But... SOLAR SAILS. Sheesh

?

Edited December 2, 2014 by Bjarne

[Sensei]

No, don't. That is nothing to do with it. But you could look at the Nichols radiometer.

http://en.wikipedia.org/wiki/Nichols_radiometer

You're the first one I see, and I hope so the last one, to suggest to *NOT* read scientific article on science forum! Pathetic.

While reading that article he could find a link to Nichols radiometer.. And learn about couple things at the same time. Things the he might not be aware of.

 

Or are you claiming that momentum of incoming photons are not conserved in Crookes radiometer?

 

In any experiment every conservation laws are obeyed from definition. Even the one you're not interested in.

 

The question I was answering "That radiation really can convert to kinetic energy,?"

Nichols radiometer reading is done by measuring heating effect. So your answer is even incorrect.

On the other hand, much of what we today call science, has never passed any scientific method, but anyway presented like, - certain knowledge.

What are you talking about?!

Edited December 2, 2014 by Sensei

[Strange]

On the other hand, much of what we today call science, has never passed any scientific method

 

For example?

 

 

Unless hard evidence really can be presented (which unfortunately, doesn’t seems to be the case) - I (at least) will remain sceptic until then. ..

 

 

1. Conservation of momentum. (It is up to you to show that this does not apply - unless you are not interested in the scientific method?)

2. Nichols radiometer.

3. Solar sails.

4. Pioneer anomaly

 

And again it is certain knowledge that it really is dark matter out there, and no other possibilities.

 

I have no idea why you say that. Initially "dark matter" was pretty much a placeholder name for "unknown effect that behaves like unseen matter". Since then many explanations have been investigated some involving forms of matter and some not. Currently, the weight of evidence is that dark matter is a form of matter but it other possibilities are still being investigated.

[Bjarne]

 

What are you talking about?!

[Sensei]

And that's how science works.

 

Show examples that don't work this way.

[Strange]

You're the first one I see, and I hope so the last one, to suggest to *NOT* read scientific article on science forum! Pathetic.!

 

That is not what I was suggesting. Bjarne is confused enough about basic physics so I didn't think it would help to get him to read something which is NOT about light pressure.

 

While reading that article he could find a link to Nichols radiometer.

 

He might. Or he might have missed it and just latched on to "not due to radiation pressure" and decided it supported his mistaken ideas.

 

. And learn about couple things as the same time. Things the he might not be aware of.

 

True. He has a lot to learn.

 

Or are you claiming that momentum of incoming photons are not conserved in Crookes radiometer?

 

They are obviously conserved but have nothing to do with the motion of the radiometer.

 

Nichols radiometer reading is done by measuring heating effect.

 

But the movement is caused by radiation pressure. And, as it uses mirrors it answers Bjarne's question about experiments that measure the force of emitted photons.

[Bjarne]

 

For example?

Everything that haven't passed the method you can read from the images attached in the previous post

 

 

1. Conservation of momentum. (It is up to you to show that this does not apply - unless you are not interested in the scientific method?)

2. Nichols radiometer.

3. Solar sails.

4. Pioneer anomaly

1.) Only (matematical based) speculation

2.) No it demonstrate hot air in motion, and has nothing with this dicussion to do

3.) I have never hear that such are tested, hence this too is only speculation

4.) Only (matematical based) speculation

 

 

I have no idea why you say that. Initially "dark matter" was pretty much a placeholder name for "unknown effect that behaves like unseen matter". Since then many explanations have been investigated some involving forms of matter and some not. Currently, the weight of evidence is that dark matter is a form of matter but it other possibilities are still being investigated.

It is today presented almost as certain knowledge that we are dealing with unknown kind of matter. Every other option is out of question

[Strange]

Aha! I knew the other place this effect would be obvious is spectroscopy. Took a while to track down a simple enough explanation:

 

Finally, we should be aware of the effect of recoil. When an atom emits a photon, the atom must recoil to conserve momentum.

http://quantummechanics.ucsd.edu/ph130a/130_notes/node429.html

 

This is an observed effect. Happy now?

 

You could also look up the Mossbauer effect but it is more complex.

Everything that haven't passed the method you can read from the images attached in the previous post

 

And can you give any such examples?

 

1.) Only (matematical based) speculation

 

I'm afraid there is only one rational response to that: nonsense. It is very obviously not speculation.

 

2.) No it demonstrate hot air in motion, and has nothing with this dicussion to do

 

No. I said NICHOLS radiometer.

 

3.) I have never hear that such are tested, hence this too is only speculation

 

No. The word for that is "ignorance" not speculation. In fact it is wilful ignorance as you have been presented with links that provide information about the PRACTICAL USE of solar sails.

 

4.) Only (matematical based) speculation

 

Er, no. Application of the scientific method. Exactly as your little diagram.

 

It is today presented almost as certain knowledge that we are dealing with unknown kind of matter. Every other option is out of question

 

That is true today because of the overwhelming evidence that that is the case (e.g. gravitational lensing). But other possibilities have been, and still are being, investigated. It is a good test case for theories like MOND (which so far fail to fit observations, strengthening the argument for some sort of matter). But matter has always been the most plausible explanation because it behaves just like matter.

http://en.wikipedia.org/wiki/Dark_matter#Alternative_theories

Edited December 2, 2014 by Strange

[Bjarne]

And that's how science works.

 

Show examples that don't work this way.

 

We know there is dark matter out there (even though there is no evidense all all)

We know that the universe is expanding (even though it is never proven that cosmological redshift only can be interpreted like this)

Ohh boy I could continue for weeks

[Strange]

We know there is dark matter out there (even though there is no evidense all all)

 

No evidence?

http://en.wikipedia.org/wiki/Dark_matter#Observational_evidence

 

And we don't "know" anything of the sort. There is just very strong evidence. Unless you are claiming that it is all fabricated?

 

We know that the universe is expanding (even though it is never proven that cosmological redshift only can be interpreted like this)

 

We don't "know" that. Nothing is ever "proven". That is not how science works. But other explanations fail to fit ALL the evidence.

 

This was a perfect example of the scientific method: theory (GR); hypothesis (universe expands); predictions (e.g. CMB), observation (redshift, CMB, many other things); experiment (more measurements); new evidence (e.g. accelerating expansion); modify theory ... and so on.

 

 

Ohh boy I could continue for weeks

 

What, demonstrating how little you know?

Edited December 2, 2014 by Strange

[imatfaal]

See Crookes radiometer

http://en.wikipedia.org/wiki/Crookes_radiometer

 

Crookes radiometer only work in partial vacua because the effect is due to imbalance of momentum gained by air molecules impacting on black and white sides of the vane (due to the temperature difference between them). The movement is not due to radiative pressure.

[Strange]

And another example:

 

The Yarkovsky effect is a force acting on a rotating body in space caused by the anisotropic emission of thermal photons, which carry momentum.

http://en.wikipedia.org/wiki/Yarkovsky_effect

 

Also: http://en.wikipedia.org/wiki/Yarkovsky%E2%80%93O%27Keefe%E2%80%93Radzievskii%E2%80%93Paddack_effect

[imatfaal]

Here is the earliest paper I can find measuring the radiative pressure of light

 

http://mesoscopic.mines.edu/mediawiki/images/3/39/Radiationpressure.pdf

 

I have not checked if it is right or not - but I think it is; note the date and how this paper was written before much of our knowledge of light was properly understoood

[Strange]

Here is the earliest paper I can find measuring the radiative pressure of light

 

http://mesoscopic.mines.edu/mediawiki/images/3/39/Radiationpressure.pdf

 

I have not checked if it is right or not - but I think it is; note the date and how this paper was written before much of our knowledge of light was properly understoood

 

And it also explicitly says that one reason for using reflective surfaces is that the radiation pressure will be twice as great as for non-reflective surfaces. Which provides (yet more) physical evidence Bjarne is asking for.

 

I hope that finishes off his claims of the violation of conservation of momentum.

[Bjarne]

Here is the earliest paper I can find measuring the radiative pressure of light

 

http://mesoscopic.mines.edu/mediawiki/images/3/39/Radiationpressure.pdf

 

I have not checked if it is right or not - but I think it is; note the date and how this paper was written before much of our knowledge of light was properly understoood

 

Still I am asking for hard evidence.

Imagine we will shot a flashlight out in space, with the lights on.

Do someone really believe that the flashlight would start accelerating opposite the light cone, as a small fantasy spacecraft in star wars ?

It simple exceeds my imagination - until hard evidence shows such thesis is correct.

 

As I see it, - we are possible using a classic mechanical model for understanding a phenomenon that belong only to quantum physics (?)

Photons experiments have shown that these are quite impossible really to understand logical or classic/mechanical.

Photons even ‘know’ - ‘beforehand’ - whether one slide is open and another closed, in a multi slide experiments.

 

I think such an important issue as the claimed radiation impact must past the scientific method, before it can be taken serious.

For me this is not only done by mathematically thesis, but only by physically test, for exsample in space.

 

It is possible to repeat Pioneer experiments, but next time with the radiation emitter a different place.

Only serveral systematically experiments can end up with the blue stamp, supporting that the scientific methods really has been passed..

Edited December 2, 2014 by Bjarne

[Strange]

Still I am asking for hard evidence.

Imagine we will shot a flashlight out in space, with the lights on.

Do someone really believe that the flashlight would start accelerating opposite the light cone

 

Yes. Obviously. You have been presented with multiple lines of evidence.

 

It simple exceeds my imagination

 

That is sad, but hardly relevant.

 

Now: please present some hard evidence that conservation of momentum is not valid. (I am going to ask the moderators to split your posts off to the Speculations forum,)