Gravity - Revision history

Igor at 14:42, 11 October 2012

2012-10-11T14:42:30Z

2012-10-11T14:39:26Z

‎Problem 1: Doppler effect with constant acceleration

2012-10-11T14:39:03Z

2012-09-11T02:35:39Z

2012-09-11T02:17:28Z

‎Problem 1

2012-09-11T02:16:52Z

‎Problem 1

2012-09-11T02:16:26Z

‎Problem 1

2012-09-11T02:16:05Z

2012-08-20T15:24:04Z

2012-07-23T21:57:09Z

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 === Problem 20: local clocks ===
-Trace the photon from [[#Okun3|problem ]] with clocks, located along the photon's trajectory (at each floor).
+Trace the photon from [[#Okun3|problem on gravitational redshift]] using clocks placed along the photon's trajectory, at each floor.
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 === Problem 1: Doppler effect with constant acceleration ===
 Consider two observers at constant distance $L$ between them, moving far from any mass, i.e. in the absence of gravitational field with constant acceleration $a$. At $t_0$ the rear observer emits a photon with wavelength $\lambda$. Calculate the redshift that the leading observer will detect.
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 === Problem 2: on the Equivalence Principle ===
 Let's suppose that an elevator's rope breaks and elevator enters the state of free fall state. Is it possible to determine experimentally, been inside, that the elevator is falling near Earth's surface?

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 === Problem 1 ===
- Stars form from gas and dust due to gravitational instability, which forces gas clouds to compress. This process is known as Jeans instability after the  famous English cosmologist James Jeans (1877 -- 1946). What is the physical cause of the Jeans instability?
+Stars form from gas and dust due to gravitational instability, which forces gas clouds to compress. This process is known as Jeans instability after the  famous English cosmologist James Jeans (1877 -- 1946). What is the physical cause of the Jeans instability?
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 === Problem 1 ===
 Observations show that stars form not individually, but in large groups. Young stars are detected in clusters, which contain, usually, several hundreds of stars, which were formed at the same time. Theoretical calculations show, that formation of individual stars is almost impossible. How could this claim be justified?

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 === Problem 1 ===
-In his Lectures on Gravitation Feynman asks: ''$\ldots$maybe nature is trying to tell us something new here, maybe we should not try to quantize gravity. Is it possible perhaps that we should not insist on a uniformity of nature that would make everything quantized?''. And answers this question. Try to reproduce his arguments.
+In his Lectures on Gravitation Feynman asks: "$\ldots$maybe nature is trying to tell us something new here, maybe we should not try to quantize gravity. Is it possible perhaps that we should not insist on a uniformity of nature that would make everything quantized?". And answers this question. Try to reproduce his arguments.
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 === Problem 1 ===
 Evidently the role of gravitation grows with the mass of a body. Show that gravitation dominates if the number of atoms in the body exceeds the critical value \(N_{cr}\simeq(\alpha/\alpha_G)^{3/2}\simeq10^{54},\) where $\alpha=e^2/(\hbar c)$ is the fine structure constant and $\alpha_G\equiv Gm_p^2/(\hbar c)$ is the ''fine structure constant'' for gravitation, $m_p$ is proton's mass.

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 === Problem 1 ===
-Richard Feynman wrote: ''The striking similarity of electrical and gravitational forces $\ldots$ has made some people conclude that it would be nice if antimatter repelled matter;''. What arguments did Feynman use to demonstrate the inconsistence of this assumption (at least in our world)?
+Richard Feynman wrote: "The striking similarity of electrical and gravitational forces $\ldots$ has made some people conclude that it would be nice if antimatter repelled matter;". What arguments did Feynman use to demonstrate the inconsistence of this assumption (at least in our world)?
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 === Problem 1 ===
 What is the difference (quantitative and qualitative) between the gravitational waves and the electromagnetic ones?