Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: xersanozgen on 08/08/2017 08:59:28
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Gravitational lens without accelerating
As known, in the theory GR the acceleration and gravity are mentioned at identical meaning.
And a light has a curved path in an accelerating elevator cabinet according to GR mentality; and this event is called "gravitational lens".
However if the cabinet has fixed speed (acceleration = 0) the light will has an inclined path instead of curved path in accordance with same GR mentality.
Please look at the figure.
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- To an observer in a lift in an inertial frame of reference (ie they experience microgravity), the light ray would appear to be moving in a straight line, at c.
- To an observer free-falling in a lift in gravitational field (ie they experience microgravity), the light ray would appear to be moving in a straight line, at c.
- To an observer in a lift moving with a constant velocity downward in a gravitational field (ie a non-inertial frame of reference), I expect the light ray would appear to be bent, and the velocity would change along its path. This is because the gravitational field would get stronger between the time the light was emitted, and the time it was detected.
To have an effective gravitational lens, the light path must be bent (diffracted), which means it travels at different speeds at different points on its path. And light taking many different paths must be brought to a point (or at least a line). The lift analogy can illustrate the behavior for light taking one path, but it can't show it for multiple paths.
Can the gravitational lens be possible without accelerating?
For practical purposes, yes.
Imagine us as observers and a distant quasar; half way in-between is a low-luminosity galaxy.
The 3 parties are far enough away that any acceleration of matter is negligible.
However, the quasar light passes near the intermediate galaxy, and its path is bent to form a magnified and distorted image of the quasar.
Here, gravitational lensing is occurring with minimal acceleration.
See: https://en.wikipedia.org/wiki/Gravitational_lens
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in the theory GR the acceleration and gravity are mentioned at identical meaning
That is incorrect. There is an equivalence between gravity and acceleration but that does not give them identical meaning. Similarly there is an equivalence between mass and energy, but again that does not give them identical meaning
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in the theory GR the acceleration and gravity are mentioned at identical meaning
That is incorrect. There is an equivalence between gravity and acceleration but that does not give them identical meaning. Similarly there is an equivalence between mass and energy, but again that does not give them identical meaning
I read again the Einstein's sentences: He says that: "the gravity is the result of accelerating. Gravity mass is equal to inertial mass." Naturally it is possible that we can overcome Einstein mentality by current cognitivity.
I believe and know that we must/can reconsider the nature events by harder discipline than Einstein's. If we study the subject personally by the method of active learning, we can perceive that the event is consist of a geometrical displacement for the final point of light; because, when the value of acceleration is zero, this displacement is realized again. In my opinion, the accelerating cannot be primary/effective factor for refracting of light path; mainly we observers (that are located relative position) have not God sight/perception or we human may want to interpret the events for our different/special aims instead of pure science.
However, gravitational lens is a reality, if we remember Schwartzchild's diameter; the gravity can stop even the light; and gravity forces can refract the light's path. The light moves by electro-magnetic cycle and the effect of magnetic areas or gravity is more reasonable instead of accelerating.
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- To an observer in a lift in an inertial frame of reference (ie they experience microgravity), the light ray would appear to be moving in a straight line, at c.
- To an observer free-falling in a lift in gravitational field (ie they experience microgravity), the light ray would appear to be moving in a straight line, at c.
- To an observer in a lift moving with a constant velocity downward in a gravitational field (ie a non-inertial frame of reference), I expect the light ray would appear to be bent, and the velocity would change along its path. This is because the gravitational field would get stronger between the time the light was emitted, and the time it was detected.
If we examine the figure, the photon (which has horizontal path) arrives to an asymmetric point because of cabinet's motion. The event is consist of a geometrical displacement and observer's relative position. The accelerating factor is not effective, because when the value a = 0, final point of the light will be come into sight of refracting again.
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@xersanozgen You appear to be confusing the gravitational field with gravitational radiation. You need to look up these definitions and understand them before you come to conclusions.
http://math.ucr.edu/home/baez/physics/Relativity/GR/grav_radiation.html
https://en.m.wikipedia.org/wiki/Gravitational_field
I have included links to each definition.
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I read again the Einstein's sentences: He says that: "the gravity is the result of accelerating."
The words Einstein used do not translate directly as you have quoted them. What he is saying is that gravity and acceleration are physically indistinguishable, that they are equivalent in mathematical and physical description.
As @jeffreyH says you are confusing terms.
"Gravity mass is equal to inertial mass."
This is true in the specific case Einstein was discussing, that of a uniform gravitational field - the equivalent of the accelerating lift. It is not true in all circumstances, although the 2 are proportional, in a non uniform field they can differ.
You have to read Einstein's original texts with an understanding of the premises he is building his statements on in order to avoid misquoting.
The event is consist of a geometrical displacement for the final point of light; because, when the value of acceleration is zero, this displacement is realized again.
The displacement is not realised again. A displacement occurs, but it is not the same one. A straight line displacement is not the same as a curved path and leads to different observed results.
If we examine the figure, the photon (which has horizontal path) arrives to an asymmetric point because of cabinet's motion. The event is consist of a geometrical displacement and observer's relative position. The accelerating factor is not effective, because when the value a = 0, final point of the light will be come into sight of refracting again.
My point exactly, the values are not the same.
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If Einstein could be alive I think he would say that “I am astonished (however I thank) for these excessive rationalizations about my relativity theories; I had considered this subject by simpler/ordinary mentality; I used generally 4D geometrical analyzing as a new method. The elevator cabinet/chest climbs a little at the time while the photon arrives to other wall; and final point of the photon marks an asymmetric point. My mentality was simple and effective.”
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The entire purpose of relativity is connected to the fact we measure distant things, using second hand energy data, such as light emissions. We don't measure a black hole directly, but rather we infer its properties based on second hand evidence connected to light or the lack of light. Relativity tells us that this second hand data, based on the speed of light, has pitfalls since what we see is dependent on reference. Einstein attempted to teach us how to deal with the pitfalls of second hand data.
For example, the mass of a star is invariant. This is not reference dependent. However ,since we can't directly weight a star, we infer the mass from light, with this light having reference problems, that we need to keep straight. The problem has to do with the age old tradition of assuming the earth is the center of the universe. This is still the most convenient relative reference, since our tools are on or near the earth. The speed of light is an absolute reference, which is the same for all references. If you use this as the ground state, the second hand data problem becomes secondary. It is no longer the rate limiting step.
The concept of space-time is not a thing, but an abstraction that tells us how the second hand light data behaves under different conditions relative to references. For example, increasing gravitational pressure causes transitional frequencies to speed up, even though the light frequency of the second hand energy data appears to slow down, due to relativity and contraction of space-time. Relativity only deals with the second hand light data and does not combine this with pressure, so one can predict phase transitions and states of entropy which add repeatable material details that are absolute; hydrogen to helium. This is done in the lab with direct simulation experiments that have nothing to with space-time. Space-time only enters the scene if we decide to use second hand energy data to define the original phenomena such as in particle accelerators.
Concepts like, there is no preferred reference is only valid if we use second hand data. Conservation of energy does not allow all situations to be the relative. This defines an absolute order. For example, if we had a train and station in relative motion, what we see can appear to indicate either can be in motion. But if we calculate the kinetic energy based on the mass of the train and the mass of the station this is not relative, but has an order, This goes beyond using second hand energy, all the way to measuring invariants directly.
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The elevator cabinet/chest climbs a little at the time while the photon arrives to other wall; and final point of the photon marks an asymmetric point. My mentality was simple and effective.”
Einstein would say that if we throw a ball horizontally in a gravity field, or an accelerating lift, we can observe its fall to be a curved path - an acceleration - not the straight line of a constant velocity fall.
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You need to read up on relativity xersanozgen. You're mixing concepts from special relativity with general relativity. GR is about the equivalence between a specifically defined type of acceleration, constantly and evenly distributed at a same gravity locally measured, indistinguishable from a 'planetary' gravity.
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Here are the results of a sky survey where they look for minor distortions in the shape of galaxies through gravitational lensing - galaxies that aren't quite ovals as viewed from Earth.
Astronomers measure how much the oval is skewed, and in which direction; from this they can estimate how much mass lies between us and the other galaxy, and in what direction.
Repeat for many thousands of galaxies, and you can estimate the distribution of mass in the universe - both visible and "dark" matter.
See: https://www.scientificamerican.com/article/cosmic-map-reveals-a-not-so-lumpy-universe/
https://en.wikipedia.org/wiki/The_Dark_Energy_Survey (a 520 Megapixel camera on the telescope!)