Testing Einstein's E=mc2 in outer space

[Jim__]

From Phys.org:

(Phys.org)—University of Arizona physicist Andrei Lebed has stirred the physics community with an intriguing idea yet to be tested experimentally: The world's most iconic equation, Albert Einstein's E=mc², may be correct or not depending on where you are in space.

...

The key to understand Lebed's reasoning is gravitation. On paper at least, he showed that while E=mc² always holds true for inertial mass, it doesn't always for gravitational mass.

"What this probably means is that gravitational mass is not the same as inertial," he said.

According to Einstein, gravitation is a result of a curvature in space itself. Think of a mattress on which several objects have been laid out, say, a ping pong ball, a baseball and a bowling ball. The ping pong ball will make no visible dent, the baseball will make a very small one and the bowling ball will sink into the foam. Stars and planets do the same thing to space. The larger an object's mass, the larger of a dent it will make into the fabric of space.

more ...

[longship]

1. Well, Einstein's paper addressed inertial reference frames.

A body under acceleration, like that of gravity, is not in an inertial reference frame.

No surprises here.

I like Frank Wilczek's formulation of that equation better, what he calls Einstein's second law.

M=E/C^2
(Mass equals energy divided by the square of the speed of light.)
Mass comes from energy. I find that very cool.

[Jim__]

3. "Most physicists ... believe that gravitational mass exactly equals inertial mass," Lebed said.

I may not be getting your point, but Lebed certainly thinks this is something of a surprise:

"Most physicists disagree with this because they believe that gravitational mass exactly equals inertial mass," Lebed said. "But my point is that gravitational mass may not be equal to inertial mass due to some quantum effects in General Relativity, which is Einstein's theory of gravitation. To the best of my knowledge, nobody has ever proposed this before."

And from wikipedia:

No physical difference has been found between gravitational and inertial mass. In experimental measurements, the two always agree within the margin of error for the experiment. Einstein used the fact that gravitational and inertial mass were equal to begin his General Theory of Relativity in which he postulated that gravitational mass was the same as inertial mass, and that the acceleration of gravity is a result of a 'valley' or slope in the space-time continuum that masses 'fell down' much as pennies spiral around a hole in the common donation toy at a chain store. Dennis Sciama later showed that the reaction force produced by the combined gravity of all matter in the universe upon an accelerating object is mathematically equal to the object's inertia [1], but this would only be a workable physical explanation if by some mechanism the gravitational effects operated instantaneously.

I'm not sure why you say there are no surprises here.

[longship]

4. I guess I didn't get the point.

Thinking before first cup of coffee can be problematic.

The devil's in the details.

I stand corrected.

[Surya Gayatri]

2. Mr. Lebed's an ambitious guy--one more seeker after the long-sought goal...

"The most important problem in physics is the Unifying Theory of Everything – a theory that can describe all forces observed in nature," said Lebed. "The main problem toward such a theory is how to unite relativistic quantum mechanics and gravity. I try to make a connection between quantum objects and General Relativity."