On Thursday, January 23, 2020 at 12:53:58 PM UTC-7, Brent wrote: > > > > On 1/23/2020 2:53 AM, John Clark wrote: > > On Wed, Jan 22, 2020 at 9:53 PM Alan Grayson <[email protected] > <javascript:>> wrote: > > >>If empty space has a residual intrinsic energy of any value greater >>> than zero, which General Relativity allows for and Quantum Mechanics >>> demands, >>> >> >> > *WRT QM, are you depending on the HUP to make this statement? AG* >> > > Quantum Mechanics demands that virtual particles give empty space an > intrinsic energy, although the number it came up with was 10^120 times > larger than what the observed value turned out to be. And IHA. > > >> then the expansion of the universe will accelerate. >>> >> >> *> Why? * >> > > Because that's what the 4D tensor equations of General Relativity say. > > >> >> If the universe is accelerating then it is open regardless of what >>> its spatial shape is, regardless of how many degrees the angles of a >>> triangle add up to (please remember the term "spatial shape" is not >>> equivalent with the term "spacetime shape"). >>> >> >> *> Maybe the issue is whether the universe has infinite or finite volume, >> and "closure" is irrelevant? AG * >> > > When you ask "is the universe infinite?" if you don't mean can you keep > getting further from your starting point forever then I don't know what you > mean by the question. > > > But that happens in an arbitrarily small space that is expanding. The > proper definition is you need infinite coordinate values to label all the > distinct points. >
How do you define "topologically closed"? I refreshed my memory last night and I don't find this concept helpful in distinguishing a sphere from a plane. Nor does the concept of connectedness. TIA, AG > > > *> **A hyper-sphere has no edge or boundary, and if it is expanding, you >> might never return to your starting point* >> > > Exactly. > > *> even though it is finite in spatial volume.* >> > > If the Universe is finite then you should be able to visit every cubic > meter of it, at least in principle. > > > Only on the principle that you can go faster than the expansion rate > between any two points of the universe...which appears to be false even for > a small part of the universe. > > But in a expanding and accelerating universe you can't. > > > Even if the universe has the topology of a sphere and hence is closed and > finite. I don't see why you have a problem with a finite, expanding space > in which you can't reach every point of it because you speed is limited. > Having limited speed and space being infinite are different things. > > Brent > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/bc0ef231-1a9f-4b53-a110-65cf721ce2fd%40googlegroups.com.
