General Relativity posits that a gravitational field is virtually indistinguishable from a smoothly accelerating frame of reference. That is, if you found yourself in a laboratory aboard a rocket accelerating at 9.81 m/s^2, you would be hard-pressed to determine, without looking out a window, by experiment alone, whether you were on the surface of a planet or in a rocket.
If a beam of light were aimed horizontally across the lab, the path it traced would curve in such a way that the observer would be unable to determine whether he was accelerating or in a gravitational field. Even though photons are massless, they respond to a gravitational field, albeit very slightly. This has been explained as a consequence of the mass-equivalence of their energy, by E=mc^2.
This thought experiment requires no optical apparatus to observe the gravitational lensing effect of a light beam being bent by either a gravitational or pseudo-gravitational (accelerating frame) field.
Well, obviously, to observe anything, you have to percieve it, in some way, either with your eyes or some instrument or detector.:dubious:
I was attempting to address the OP’s “optical error” caveat:
If a laser is shined through a dusty or smoky chamber, the beam is quite visible with the unaided eye, without any optical device or lens to introduce “optical errors”.
Particle accelerators use beam detectors to trace the path of speeding particles and gamma rays resulting from high-speed collisions between subatomic particles, which produce a shower of debris including quarks, gluons, mesons and various forms of matter and energy. These detectors may, but usually do not, use optical elements, such as glass lenses or mirrors to plot the path of the detected elements.
There are many ways to percieve the natural world, without actually seeing it. Many of our most cherished scientific advances have come about from processes which we know exist, but cannot percieve with our unaided senses.
“Gravitational Lensing” is not strictly an optical phenomenon, and the curvature of space-time in higher dimensions is an accepted proposition by most in the scientific community.
To address the comment in the OP:
I attempted to propose a visualization which would obviate the complicating distraction of a stricly “optical” detector.
Most notably, Steven Weinberg describes curvature of spacetime as a mathematical shortcut that should not be construed as what’s actually happening in his classic GR textbook. I’ve heard, though, that he’s since changed his view on it.
Eddington subsequently (and rightly) was awarded a knighthood and the Order of Merit (the biggie). But he was never a peer, so he never became Lord Eddington.
Einstein, jokingly or not, was clearly referring to the Almightly. Who, much as some of them may believe so, is not the Plumian Professor of Astronomy at Cambridge.
First of all, tornadoes don’t get hypersonic. Second, even if they did, they wouldn’t develop event horizons. Third, what does that have to do with anything in this thread?
First of all, I agree not on earth. Second, it is not beyond my imagination that a wind might exceed the relative speed of sound energy. Third, there is no need for letting. The god I trust does not need let.
Not commonly at least. But I certainly recall some actual scientists claiming that it appeared to be possible that wind in the right kind of tornado under the right kind of conditions could exceed the speed of sound. If I had to guess, I’d say I read it in a National Geo Mag within the past few years that had a big spread on tornados. And if a tornado had hypersonic winds, it would certainly have a horizon that would be eventful to cross
Only little is known about light and gravity and this sounds like “university book stuff” - though I never read one:dubious:. Can you use ie. Jupiter (mass one-thousandth of the Sun) to get real-time readings every night? Instead of parabolic lenses, could you use carefully placed tubes to get the light’s intensity (which should be much less, because of the grown distance). I still think that it is more of light’s properties than gravity envolved here. I quess, you will disagree.
Yes we will. Because gravitational lensing is an observed phenomenon seen at different wavelengths using different detection techniques. The cites that both I and Bytegeist linked you to show the same phenomenon, at the same point in space, happening at the same time. The optical image uses traditional lenses and mirrors, the radio image uses a technique called “synthesis imaging” – two very different detection techniques. And yet we see the same thing. We see examples of “micro-lensing” where small, compact bodies bend the light of distant stars and quasars.
Why do you have the big beef with gravity bending light? Why is it so hard for you to accept that light can be bent by gravity?
My mind is set to a simpler reality, where both light and sound are waves (nothing but waves). Space-time curvation was only an idea and became manifested because nobody came up with something else.
