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hoola

unruh radiation and thruster mechanisms

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Posted (edited)

What functional relation is there, if any,  to Unruh radiation emitted under high velocities by an accelerated spaceship,  and of stationary thrusters, either the Woodward  device, which accelerates a phononic shock wave, or the Shawyer device which accelerates microwave standing waves in a sealed cavity? Here I am presuming that the NASA work showing the Shawyer device to work as legitimate, hence my interest in this area.

Edited by hoola

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I would say zero. Why do you think there is a connection?

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Posted (edited)

As both seem to be the collision of matter into a region that normally is undisturbed, unless by a abnormal situation in where the VP pair's structure, which is determined from the first instant, is a mirror of what should be it's perfect antiparticle. By the time the energy waveform hits the second instant, matter normally not present is near enough to have quantum effects show up. This is the distortion factor in common.

Edited by hoola

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Posted (edited)

Unruh radiation is not emitted by an accelerating ship.  There is also no collision of matter going on in that scenario.

There's merely a coordinate singularity inherent in a continuous accelerated reference frame, which, only in that ARF, emits faint radiation at the singularity similar to the Hawking radiation (which is also not emitted by any ship) emitted in say an inertial reference frame at the coordinate singularity of the event horizon of a black hole  

In both cases, the radiation is not emitted in coordinate systems where there exists no coordinate singularity there.

Edited by Halc

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Posted (edited)

Unruh radiation is a frame dependent effect, while a thrust, which generates a force, and resultant acceleration, is an absolute effect ( NOT frame dependent, but present in ALL frames ).

Note the difference ?

( although Unruh radiation is caused by an accelerating frame )

Edited by MigL

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If a ship is near relatiivistic speed, it can measure Unruh radiation at the ship's location, and not to a stationary observer  watching it going by,  correct? The same with Hawking radiation.....it could be measured at or near the event horizon, but not at a distance?  If so, it that because the info in either case is red shifted away ?

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I'm not very familiar with Unruh radiation and Rindler horizons, so perhaps some of the more learned members can provide more details.

Here's what Wiki has to say about the Unruh Effect...

"In modern terms, the concept of "vacuum" is not the same as "empty space": Space is filled with the quantized fields that make up the universe. Vacuum is simply the lowest possible energy state of these fields.

The energy states of any quantized field are defined by the Hamiltonian, based on local conditions, including the time coordinate. According to special relativity, two observers moving relative to each other must use different time coordinates. If those observers are accelerating, there may be no shared coordinate system. Hence, the observers will see different quantum states and thus different vacua.

In some cases, the vacuum of one observer is not even in the space of quantum states of the other. In technical terms, this comes about because the two vacua lead to unitarily inequivalent representations of the quantum field canonical commutation relations. This is because two mutually accelerating observers may not be able to find a globally defined coordinate transformation relating their coordinate choices.

An accelerating observer will perceive an apparent event horizon forming (see Rindler spacetime). The existence of Unruh radiation could be linked to this apparent event horizon, putting it in the same conceptual framework as Hawking radiation. On the other hand, the theory of the Unruh effect explains that the definition of what constitutes a "particle" depends on the state of motion of the observer."

from     https://en.wikipedia.org/wiki/Unruh_effect

Up until now, my own personal take on the Unruh effect, whether right or wrong, always considered acceleration as a gravitational field ( by the equivalence principle ), such that the EM fields which fill space, are blue-shifted towards the accelerating frame just as they would be into a gravitational well. This blue shift is 'seen' as an increase in temperature, by the accelerated frame.

I am open to better/accurate explanations, as I am just starting to look into it myself.

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9 hours ago, hoola said:

If a ship is near relatiivistic speed, it can measure Unruh radiation at the ship's location, and not to a stationary observer  watching it going by,  correct? The same with Hawking radiation.....it could be measured at or near the event horizon, but not at a distance?  If so, it that because the info in either case is red shifted away ?

Speed has nothing to do with it, since in your example, the situation is no different than the ship being stationary and the observer watching it go by being what moves at relativistic speed.

Unruh radiation is observed in an accelerating reference frame, and has nothing to do with speed.

Hawking radiation can be measured at any distance from an event horizon, but only by a hovering observer, not by one falling in.

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