John Helly's latest activity
-
JJohn Helly reacted to phinds's post in the thread Undergrad Where did the early photons go? with
Like.
@John Helly you might find this helpful: https://www.physicsforums.com/insights/balloon-analogy-good-bad-ugly/ -
JJohn Helly reacted to Cerenkov's post in the thread Undergrad Where did the early photons go? with Like.
jbriggs444 What you describe is difficult to envisage for the layman who can't to do the math to understand it that way. But through...
-
JJohn Helly reacted to PeterDonis's post in the thread Undergrad Where did the early photons go? with Like.
You can't make this statement without specifying a coordinate chart. There is no such thing as "moving" or "not moving" in any absolute...
-
JJohn Helly reacted to PeterDonis's post in the thread Undergrad Where did the early photons go? with Like.
Not really no. The viewpoint that "nothing is moving through space, but space itself is expanding", and the viewpoint that "objects are...
-
JJohn Helly reacted to PeterDonis's post in the thread Undergrad Where did the early photons go? with Like.
Yes, when @jbriggs444 said "nothing is moving", he was (implicitly) using a comoving coordinate system. That's the most common...
-
JJohn Helly reacted to DaveC426913's post in the thread Undergrad Where did the early photons go? with Like.
How about 'Light takes longer to travel between them'?
-
JJohn Helly reacted to PeterDonis's post in the thread Undergrad Where did the early photons go? with Like.
That's an invariant which is due to the invariant expansion scalar, yes.
-
JJohn Helly reacted to PeroK's post in the thread Undergrad Where did the early photons go? with Like.
The simplest mathematical example that illustrates an infinite universe is the number line. With 0 in the middle (although...
-
JJohn Helly replied to the thread Undergrad Where did the early photons go?.Ok. The 1D example is helpful. Is there a place in the literature I can start to find the math that underlies this? I would like to...
-
JJohn Helly replied to the thread Undergrad Where did the early photons go?.I interpret this as analogous to 'zooming' a view in an image. The coordinates are not changing but user's viewport is.
-
JJohn Helly replied to the thread Undergrad Where did the early photons go?.Mahalo. I will have to ponder this for a while.
-
JJohn Helly replied to the thread Undergrad Where did the early photons go?.Ah.
-
JJohn Helly replied to the thread Undergrad Where did the early photons go?.Ok. But what was expanding, then, and still is? Must be some kind of domain? Excuse me, I'm an earth scientist trying to wrap my head...
-
JJohn Helly replied to the thread Undergrad Where did the early photons go?.Mahalo. I will read the link.
-
JJohn Helly replied to the thread Undergrad Where did the early photons go?.What scale factor? What is being scaled if the domain is infinite?