Recent content by yogi

Einstein claimed in Part IV of his 1905 paper ..."if at points A and B ...stationary clocks viewed in the stationary system, are synchronous ; and if the clock A is moved with velocity v along a line AB to B, then on its arrival at B, the two clocks no longer synchronize, but the clock moved...

That is true - thank you for pointing that out. A centrifuge may not meet the conventional definition of an inertial system - just as a satellite in circular orbit experiences constant centripetal acceleration, it is non the less a perfectly good inertial frame - as pointed out by Penrose. In...

This is a general comment, not directed to any particular post. The premise that all inertial frames are equivalent is at the heart of SR, but it has never been experimentally verified, and indeed may not be verifiable. Experiments are made with reference to the Earth - a clock accelerated...

The notion of curvature of nothing is based upon Einstein's formulation of space as static. Using Friedmann's equation rho = [q][3H^2/4piG)] and taking q per de Sitter [c^2/R], the dynamic solution for a zero energy universe [(rho)(c^2)/3 = -P] leads to the same result as lambda = G as...

The subject poses a curious side question - whether accelerating expansion requires dark energy - if (d/dt)[mv] = 0 during accelerated expansion, an increase in the inertial value of existing mass, ... well ...it might be something to muse over after a few drinks, or maybe more than a few.

Since the original question is more of a survey - I will weigh in with my own interpretation of space as a functional entity. My background is engineering - I have BS, MS and JD degrees. Einstein notably changed his position on space as an ether during the years spent developing GR, he...

Perhaps you can embellish upon that a bit... it would seem to me that the w = -1/3 is tantamount to a mandated state for a net zero energy universe. i.e., expanding negative pressure creates positive energy (a la McCrea) at the same rate that negative potential grows due to the expanding volume...

If you model the universe as a black hole - the escape velocity is c - the Schwarzschild radius R* is the Hubble radius R - and all energy in the Hubble universe in any form is expressed in terms of its mc^2 equivalent as M (except the interaction gravitational energy of the Hubble sphere). To...

That is true, but for the purposes of modeling the now state of the universe, its mostly matter and very little in the way of relativistic velocities wrt to space ...expansion is relativistic - but this doesn't add to the relativistic energy because the nebula are commoving with recessional...

In 1934 McCrea and Mill, using only energy relationships and Newtonian mechanics, derived the same gravitational equations as those that had been synthesized from GR by considerable effort and skill. For purposes of understanding, there is nothing wrong with using Friedmann's formulations -...

Let me embellish upon your response with simple analogy. If space is modeled as a two sphere with one dimension suppressed, then would the interior rate of time passage be different than the exterior rate? If so could that be an unbalancing cause? I am not sure the analogy is appropriate, and...

Hi Peter Lets take a very large or infinite universe - gravitational attraction would appear to be equalized in all directions.

I have Misner, Thorne and Wheeler. Can you direct to a particular page or section where this issue is treated.

The slowing eras of cosmological expansion are generally justified as being due to gravity. How is gravitational slowing justified in a flat or nearly Flat universe. If the universe were closed or if our Hubble sphere were the complete universe, gravitational slowing is a logical consequence...

I know you are a professional cosmologist, but I will still take issue with your statements. The OP's question was "where does the value of 10^-35 sec^-2 come from, and that answer comes from History, it had to have a value that counteracted the obvious potential for gravitational collapse...