Recent content by Cerenkov

With apologies Peter, I'm not feeling very well right now and will get back to you asap. Cerenkov.

Thank you. Thank you. Now this needs unpacking. If the type 1a finding holds, then our universe doesn't satisfy the condition of accelerated expansion during the last 2 billion years. They imply that accelerated expansion never happened. So dark energy is not the cause of that. It never...

Thank you. Thank you. Thank you again. I suspected this was the case. But thank you for confirming it. Cerenkov.

Thank you for this, Peter. In my defence I'm only using Hawking's book as a starting point for my line of questions. Cerenkov.

Then these three assumptions were proper to papers by Hawking and Penrose prior to the 1970 paper? Thank you. Ok, let's be specific here, so that I get this right. Are you talking about these four energy conditions described in the 1970 paper's abstract? (i) Einstein’s equations hold (with...

I've been thinking some more about the Hawking - Penrose Singularity theorem and was wondering if you could help me gain a better understanding of the assumptions they made when they wrote it, in 1970. In Hawking's book, A Brief History of Time (chapter 3, page 25) he writes.... In 1965 I...

I humbly accept your compliment. :wink:

Why thank you, sbothy. :smile: But how can I be better informed than you if I've asked all the questions you had? We must be on a par to have thought of the same questions. :wink: Cerenkov (who is a he, btw)

https://science.nasa.gov/dark-energy/ If memory serves Peter, to account for the speeding up of cosmic expansion scientists invoked Dark Energy. But if it is found that Perlmutter et all made the wrong assumptions about the standard candles they were using and the universe isn't accelerating...

Which may not be the case if the new analysis of type 1a supernovae holds up? Would you please explain what it mean if the Perlmutter's 1998 finding were overturned by this new finding? What would the implications be for the cosmological constant? Would it's value need to be revised? Thank...

So I've tripped up on my use of terms. What I should have said was that the proof is mathematically valid, but, in accordance with what Hawking and Penrose wrote, it does not apply to OUR universe. Because the measured value of our universe's cosmological constant appear to be positive and the...

Ok, thanks for clarifying and explaining Peter. Now, just off the top of my head I seem to recall that there's a theorized scenario that's neither accelerated expansion or collapse. Where the universe expands at a slower and slower rate but never actually comes to a halt. Is that right? If...

https://www.physicsforums.com/threads/the-singularities-of-gravitational-collapse-and-cosmology.968323/#post-6149795 It seems that I didn't recall things correctly Peter. We did discuss the energy conditions of that paper by Hawking and Penrose. But the key point is found in the abstract...

Thanks very much for your help pinball1970 and Ibix. So, let me see if I understand this. Perlmutter et al worked on the premise that type 1a supernovae could be treated as 'standard candles' and on the back of this assumption, in 1998, they found that the expansion of the universe was...

Hello Peter I'm interested in the issue of the universe's apparent accelerated expansion and would like to learn more. Could you please bring the abstract down a level or two so that I can understand what it says more readily. Thank you, Cerenkov.