## Important/Stupid Question?

Espouse, rant, and rebut -- politely.

### Important/Stupid Question?

Regarding the Venus transit -- and specifically the June 13 post A Venus Transit Over the Baltic Sea
Image Credit & Copyright Jens Hackmann -- I became curious about gravity and the warping of the fabric of space. Using the common example of a bowling ball on a trampoline representing the sun and space fabric respectively, it seems when looking at this picture that Venus, if it were sitting on the same space fabric as the Earth, would be lower in the frame. Unless...

... and I am probably obviously a big time amateur for asking this...

A) Each mass/object is sitting on its own space fabric? And operating independently of other masses/objects?
B) The space fabric is rippled or wavy? And not stretched tight?

Note: B is starting to seem correct to me after writing this down.

This is heavy stuff. Pun intended. And it's giving me a headache. Somebody help!
Dodd Clifton
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### Re: Important/Stupid Question?

Dodd wrote:I became curious about gravity and the warping of the fabric of space. Using the common example of a bowling ball on a trampoline representing the sun and space fabric respectively, it seems when looking at this picture that Venus, if it were sitting on the same space fabric as the Earth, would be lower in the frame.

The trampoline example is an analogy, designed to help visualize something that can't be directly visualized. Spacetime is 4-dimensional. Most people can't picture that. What the trampoline visualization does is shows the effect of mass on 3-dimensional spacetime. In that universe, space is 2D (everything exists on the plane of the trampoline), and mass distorts that plane in a direction that is non-spatial- a direction that the inhabitants of the universe can't see. They only know that the distortion is present because geometry changes: things they believe to be traveling in straight lines no longer are.

You can't see the distortion of spacetime caused by Venus- it simply isn't massive enough to produce visible effects. But the Sun is, and we observe that the light from stars appears to bend as it passes around the Sun's limb. But our theory tells us that light only travels in straight lines, so we infer that spacetime has become distorted- making a straight line appear curved from our perspective.
Chris

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Chris L Peterson
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Chris Peterson
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### Re: Important/Stupid Question?

Dodd wrote:
A) Each mass/object is sitting on its own space fabric? And operating independently of other masses/objects?

Each mass/object slightly warps the space-time fabric.

Now, everything is traveling through time at the speed of light.
Hence, the small bending of time by the earth causes baseballs to bend in parabolic orbits (consistent with Newtonian physics).

Photons are also traveling through space at the speed of light.
Hence, the small bending of BOTH space AND time by the sun causes photons to bend twice as much as one would normally expect.

Note that: Keplerian elliptical orbits are totally the result of the small bending of time by the Sun; whereas, the small
general relativitic precession of speedy Mercury's elliptical orbit is caused by the small bending of space by the Sun.

http://en.wikipedia.org/wiki/Arthur_Edd ... Relativity wrote:
<<During World War I, Sir Arthur Stanley Eddington, (28 December 1882 – 22 November 1944) was Secretary of the Royal Astronomical Society, which meant he was the first to receive a series of letters and papers from Willem de Sitter regarding Einstein’s theory of general relativity. Eddington was fortunate in being not only one of the few astronomers with the mathematical skills to understand general relativity, but (owing to his internationalist and pacifist views) one of the few at the time who was still interested in pursuing a theory developed by a German physicist. He quickly became the chief supporter and expositor of relativity in Britain. He and Astronomer Royal Frank Watson Dyson organized two expeditions to observe a solar eclipse in 1919 to make the first empirical test of Einstein’s theory: the measurement of the deflection of light by the sun's gravitational field. In fact, it was Dyson’s argument for the indispensability of Eddington’s expertise in this test that allowed him to escape prison during the war.

After the war, Eddington travelled to the island of Príncipe near Africa to watch the solar eclipse of 29 May 1919. During the eclipse, he took pictures of the stars in the region around the Sun. According to the theory of general relativity, stars with light rays that passed near the Sun would appear to have been slightly shifted because their light had been curved by its gravitational field. This effect is noticeable only during eclipses, since otherwise the Sun's brightness obscures the affected stars. Eddington showed that Newtonian gravitation could be interpreted to predict half the shift predicted by Einstein. (Somewhat confusingly, this same half-shift was initially predicted by Einstein with an incomplete version of general relativity. By the time of the 1919 eclipse Einstein had corrected his calculations.)

Eddington's observations published the next year confirmed Einstein's theory, and were hailed at the time as a conclusive proof of general relativity over the Newtonian model. The news was reported in newspapers all over the world as a major story. Afterward, Eddington embarked on a campaign to popularize relativity and the expedition as landmarks both in scientific development and international scientific relations.

Throughout this period Eddington lectured on relativity, and was particularly well known for his ability to explain the concepts in lay terms as well as scientific. He collected many of these into the Mathematical Theory of Relativity in 1923, which Albert Einstein suggested was "the finest presentation of the subject in any language." He was an early advocate of Einstein's General Relativity, and an interesting anecdote well illustrates his humour and personal intellectual investment: Ludwig Silberstein, a physicist who thought of himself as an expert on relativity, approached Eddington at the Royal Society's (6 November) 1919 meeting where he had defended Einstein's Relativity with his Brazil-Principe Solar Eclipse calculations with some degree of scepticism and ruefully charged Arthur as one who claimed to be one of three men who actually understood the theory (Silberstein, of course, was including himself and Einstein as the other two). When Eddington refrained from replying, he insisted Arthur not be "so shy", whereupon Eddington replied, "Oh, no! I was wondering who the third one might be!">>
Art Neuendorffer

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### Re: Important/Stupid Question?

Thanks, guys. I'm getting smarter... or at least learning more. Dodd
Dodd Clifton
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