[CrazyScientist (OP)]

Yet, it's purpose wasn't to see if photons have potential energy, but to see if their kinetic energy will be altered due to influence of an external graviatational field.

That's the same thing as measuring the gravitational potential energy of the photons. Kinetic energy doesn't come out of nowhere. If the kinetic energy of the photon is increased, that is because some of the potential energy it had has been transformed into kinetic energy. It's the exact same thing that happens when you drop a heavy object. Some of the heavy object's gravitational potential energy is transformed into kinetic energy as it accelerates.

You're right - the increased energy of photon doesn't go from nowhere. But it doesn't also come fromt the potential energy of that photon - it comes from the kinetic energy of interacting massive body. Because of it's potential energy massive objects can be decelerated from 9999% of c to 0 and then accelerated back to the same speed without any loss of the rest-mass. If you slow down to 0 a photon propagating in free space, it will disappear...

[CrazyScientist (OP)]

To have potential energy, they would have to induce a force on a massive objects from distance

Due to conservation of momentum, we know that they do exactly that via gravity.

Is there any change in the energy state of a massive source, before the absorbtion/reflection of the photon it interacts with. Because the gravirtional red-shift is a  purely relativistic effect, that has no effect on the energy state of source in it's own frame

[CrazyScientist (OP)]

Which also is kinetic (induces force)

No.
https://en.wikipedia.org/wiki/Kinetic_energy

Yes.
https://en.wikipedia.org/wiki/Force

But to be clear: by "kinetic" i mean "capable of inducing a definitive change in energy state"

[Origin]

But to be clear: by "kinetic" i mean "capable of inducing a definitive change in energy state"

So when you say kinetic energy, you don't mean kinetic energy??!

[Kryptid]

it comes from the kinetic energy of interacting massive body.

Citation needed.

Is there any change in the energy state of a massive source, before the absorbtion/reflection of the photon it interacts with.

Yes. The gravity of the photon pulls on the massive source, thus causing it to accelerate as well (very slightly).

[CrazyScientist (OP)]

it comes from the kinetic energy of interacting massive body.

Citation needed.

Is there any change in the energy state of a massive source, before the absorbtion/reflection of the photon it interacts with.

Yes. The gravity of the photon pulls on the massive source, thus causing it to accelerate as well (very slightly).

https://www.researchgate.net/publication/265258824_THE_GRAVITATIONAL_POTENTIAL_ENERGY_OF_PHOTONS_IS_AGAINST_THE_EXPERIMENTAL_EVIDENCE

https://www.quora.com/What-is-the-potential-of-a-photon

Funny, how different answers are in contradiction to dach other...
On the second hand I can give you one simple explanation, why photons can't induce a gravitational pull on massive object - it's not possible since both photons and gravity propagate at Constantin speed of light - If you would be correct, gravity of photons would have to exceed the speed of light and recent experiments show that it's not the case...

[Bored chemist]

Funny, how different answers are in contradiction to dach other.

They don't contradict each other.

[Origin]

On the second hand I can give you one simple explanation, why photons can't induce a gravitational pull on massive object - it's not possible since both photons and gravity propagate at Constantin speed of light - If you would be correct, gravity of photons would have to exceed the speed of light and recent experiments show that it's not the case...

That is the wrong conclusion.  If we used your conclusion for sound that would mean that if a jet flew by you at 343 m/s, since that is also the speed of sound, then you would never hear the jet.  That doesn't seem right, does it?

[Bored chemist]

It depends, how you define "pseudoscience". For me, pseudoscience is everything, what tries to look like science, while being experimentally disproven or being beyond any kind of practical verification.

So, everything you wrote in this thread then?

https://www.thenakedscientists.com/forum/index.php?topic=82373.msg658175#msg658175

[Kryptid]

why photons can't induce a gravitational pull on massive object

We know for a fact that they do. Gravitational lensing occurs when a massive object's gravity pulls on light. That changes the momentum of the light. In order for conservation of momentum to be satisfied, the light must also pull on the massive object.

If you would be correct, gravity of photons would have to exceed the speed of light and recent experiments show that it's not the case...

Gravity doesn't travel. It's only changes in a gravitational field that travel at the speed of light.

[CrazyScientist (OP)]

On the second hand I can give you one simple explanation, why photons can't induce a gravitational pull on massive object - it's not possible since both photons and gravity propagate at Constantin speed of light - If you would be correct, gravity of photons would have to exceed the speed of light and recent experiments show that it's not the case...

That is the wrong conclusion.  If we used your conclusion for sound that would mean that if a jet flew by you at 343 m/s, since that is also the speed of sound, then you would never hear the jet.  That doesn't seem right, does it?

And will you hear a jet incoming directly at you with supersonic speed?

Will you be able to see light emitted by a source incoming at 100% c?

.

why photons can't induce a gravitational pull on massive object

We know for a fact that they do. Gravitational lensing occurs when a massive object's gravity pulls on light. That changes the momentum of the light. In order for conservation of momentum to be satisfied, the light must also pull on the massive object.

If you would be correct, gravity of photons would have to exceed the speed of light and recent experiments show that it's not the case...

Gravity doesn't travel. It's only changes in a gravitational field that travel at the speed of light.

If Sun would suddenly disappear, it would take 499s until we would notice it on Earth - both visually and gravitationally... So, it should be ok to tell, that gravity just like the light light propagates at c. Explain me the mechanism that allows  the interaction between distant sources of light/gravity movig towards each other at c. How a planet can interact gravitationally with a star that moves towards it at 100% c?

[CrazyScientist (OP)]

But to be clear: by "kinetic" i mean "capable of inducing a definitive change in energy state"

So when you say kinetic energy, you don't mean kinetic energy??!

 Kinetic force applies work on a body, increasing it's kinetic evergy.

Ok, here's an interesting question - what will happen, if we take a body of rest mass m and and use energy equivalent to that mass (or greater) to accelerate it?

[Origin]

Kinetic force applies work on a body, increasing it's kinetic evergy.

Nice try.

Ok, here's an interesting question - what will happen, if we take a body of rest mass m and and use energy equivalent to that mass (or greater) to accelerate it?

In physics we use a force to accelerate a mass.

[Bored chemist]

Will you be able to see light emitted by a source incoming at 100% c?

No such source can exist.

[Kryptid]

So, it should be ok to tell, that gravity just like the light light propagates at c.

The change in gravity is what propagates at c.

Explain me the mechanism that allows  the interaction between distant sources of light/gravity movig towards each other at c.

Gravitational lensing doesn't happen that way. It only occurs when the light is moving at an angle to the massive object, not directly towards or away from it.

[CrazyScientist (OP)]

Kinetic force applies work on a body, increasing it's kinetic evergy.

Nice try.

Ok, here's an interesting question - what will happen, if we take a body of rest mass m and and use energy equivalent to that mass (or greater) to accelerate it?

In physics we use a force to accelerate a mass.

Thing is, that force is a vector, while energy is a scalar. However applied force multiplied by time or distance gives a scalar work, which then can be translated to ΔEk making a clear connection between energy and force. Thing is, that physicists don't know yet, how to connect it all together in a single equation of mass, motion and energy. Here's a nice discussion about this subject:

https://www.researchgate.net/post/Is_there_a_relation_of_equivalence_between_energy_and_force_like_mass_energy_equivalence_in_the_nature_of_physics

One would think, that when it comes to the basic Newtonian mechanics of macroscale bodies, there can't be possibly anything more to add or change - and yet physicists have no idea, how to relate the energy of a massive body to the force which it induces on other bodies...

Let me help: motion of a massive object is defined  by 2 main properties: energy and momentum and to get a complete picture of energy  state for a moving mass, both values have to be included. E=mc² is in fact only just 1/3 of the equation - part that describes the scalar energy of mass moving at limiting velocity c and since m≠E, it doesn't even make an actual mass/energy equivalence, in a true meaning. To get a true equivalence of mass/energy, we have to iclude it's momentum, so we can get m= - and only in such form we are able to juggle freely with all of it's 3 parts, without messing up the formulas for E and p.

And only now it will be possible to find the proper relation between scalar and vector values of energy and force. To make it happen, we need to distribute change of energy state (work) in a  distance/area/volume.- and from here it should be possible, to define the spatial properties of force fields.

So, it should be ok to tell, that gravity just like the light light propagates at c.

The change in gravity is what propagates at c.

Still, my point holds - motion causes changes in gravity due to displacement of massive object in the field. Gravitational intertactions are delayed in time due to the limited speed of informatioln transfer at c,  thus  obejcts moving at relative speed of c can't interact with each other at distance - the only way for them to interact, is to directly collide with each other. Amen.

Explain me the mechanism that allows  the interaction between distant sources of light/gravity movig towards each other at c.

Gravitational lensing doesn't happen that way. It only occurs when the light is moving at an angle to the massive object, not directly towards or away from it.

Then what about gravitational redshift of massive light sources?

[Kryptid]

thus  obejcts moving at relative speed of c can't interact with each other at distance

The photon will still interact with the gravitational field as it moves through it (resulting in red shift or blue shift). The reaction of the massive source will just be delayed until the change in the photon's gravitational field reaches it.

Then what about gravitational redshift of massive light sources?

That wouldn't be gravitational lensing. The photon is still interacting with the gravitational field as it passes through it. That's what causes the red shift.

[CrazyScientist (OP)]

thus  obejcts moving at relative speed of c can't interact with each other at distance

The photon will still interact with the gravitational field as it moves through it (resulting in red shift or blue shift). The reaction of the massive source will just be delayed until the change in the photon's gravitational field reaches it.

Then what about gravitational redshift of massive light sources?

That wouldn't be gravitational lensing. The photon is still interacting with the gravitational field as it passes through it. That's what causes the red shift.

Point is, that photons are not the source of an interaction (force/work), but the mean of which interaction between massive bodies occurs. They also work under somewhat different laws of physics, since their relative velocity doesn't change due to gravity...

[CrazyScientist (OP)]

Will you be able to see light emitted by a source incoming at 100% c?

No such source can exist.

Just like a point-mass, perfect vacuum or Absolute 0 - since when it bothers anyone in theoretical physics...?

[Bored chemist]

You can often talk about a hypothetical "perfect vacuum", but not when you are discussing things like vacuum energy.
Similarly, you can't talk about an object travelling at c when discussing relativity.

So the answer to your question is "it bothers theoretical physicists when it's a really obviously stupid thing to do".



On a tangentially related note, have you decided which charity yet?
https://www.thenakedscientists.com/forum/index.php?topic=82373.msg658175#msg658175