Recent content by Jim Hasty

In response to Pervect and PeterDonis, I understand your comments now thank you. I agree that the use of "geodesic deviation" was not justified in my problem statement since the equation is derived by analyzing variations between "nearby geodesics", such as at the Earth's surface and 1 meter...

The problem for calculating gravity's acceleration at the Earth's surface was one that I "made up" after studying black holes. I was wondering if the tidal forces equation would predict, in a straight forward way. Since mass tells spacetime how to curve, and the Riemann tensor in the geodesic...

I very much appreciate all of the responses. I need some time to digest them to reply. Thanks.

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I have tried twice now to calculate acceleration of gravity using the general relativistic equation of geodesic deviation and both times my solution is twice the correct answer. What am I doing wrong? As an example here is one problem: Calculate the acceleration of gravity g at the earth’s...

Thank you so much, George. This is incredible and helpful.

Can anyone in the cosmology community direct me to hard research data that specifically demonstrates: there is no detectable redshift difference in stars that are the same distance from the Earth but in all different directions. This is of course related to 'does the universe have a preferred...

Here is my story. I'm 62 and a retired engineer. In the 70's when I first started college I was very interested in science and math, especially physics. But I reasoned exactly as you are now - what is the most practical path figuring in job demand, family, pay, etc. I chose engineering and...

I have read somewhere that the electrons inhabit orbital shells around the nucleus; each shell a different radius. When an electron drops to a lower shell closer to the nucleus it must give up a quanta of energy - and vice-versa when moving to higher shells. Quanta come in only discrete...

Update on my recent reply. I see what you mean now by 'preferred frame' in the context of the cosmological principle. There are several googled articles [2011-2012] which mention 'preferred frames' in the context of 'asymmetrical expansion'. So yes, I agree with you in that context.

Yes, I see that now. I did a little geometry and math and the fit with observations is much better using the 'surface of a balloon' analogy. In the google research I found some discrepancies with the cosmology principle [2011-2012] but a recent article [2014] validates symmetrical expansion...

Why is it a 'preferred frame of reference' ? A frame in line with a center of mass is no more preferred than any other frame I choose to use. I am free to choose any frame of reference and the laws of physics are equally valid in all frames. I respectfully disagree that the universe having a...

But what if the expansion of space was accelerating with distance from the singularity, i.e. the epicenter of the universe, like we see today? Then if you looked in the direction of the expansion those galaxies would be accelerating away from you; and looking in the direction of the center...

Thanks. I am currently reading (again) your write up on the 'Balloon Analogy" - which I complement you on as very well written. I need to study more, but for now I do need confirmation on my understanding if you have time to answer, just to make sure I have this right. (1) My understanding...

No, Phinds. I apologize; that is far from the truth about my intent. My hot button is people that reply to questions with an aire of "this is the way it is believe it or go away". And I apologize in advance for my next questions: (1) do you have any references to specific data (not...