User talk:Yukterez

Expansion of Space, not Spacetime

Space and time do form spacetime in general relativity, but it is a common misconception to talk about an expanding spacetime instead of an expanding space in cosmology, see

In an expanding space the distance between points grows with time, while an expanding spacetime would imply that even the duration between events would grow, which is discussed in non-mainstream theories like

Expanding Space Time Theory (EST)

but not in standard cosmology. Therefore all articles which confused space with spacetime were fixed.

-- ❇ 21:20, 5 February 2016 (CEST)

A barnstar for you!

The Defender of the Wiki Barnstar

For your correction of the "spacetime" issue and for the creation of animations that convey the comoving universe - To which I still have trouble conceptualizing, despite your animation.

I nonetheless, commend you.

We need more clear thinkers like you. Boundarylayer (talk) 13:32, 4 February 2017 (UTC)[reply]

I have sent you a note about a page you started

Hello, Yukterez. Thank you for your work on Kerr–Newman–de–Sitter metric. User:SunDawn, while examining this page as a part of our page curation process, had the following comments:

Thank you for writing the article on Wikipedia! I genuinely appreciate your efforts in creating the article on Wikipedia and expanding the sum of human knowledge in Wikipedia. Wishing you and your family a great day!

To reply, leave a comment here and begin it with {{Re|SunDawn}}. Please remember to sign your reply with ~~~~. (Message delivered via the Page Curation tool, on behalf of the reviewer.)

✠ SunDawn ✠ (contact) 04:22, 12 October 2023 (UTC)[reply]

Photon orbits around a Kerr black hole - Figure legend

Hello, Yukterez. Could you explain the legend "A rotating black hole has 9 radii between which light can orbit on a constant r coordinate" For my part, I think there are an infinite number of constant radial coordinates for a spinning black hole. When |a| = m, these coordinates range from 0 to 4. Thank you for your answer. Cornelius Fyla (talk) 14:33, 2 August 2025 (UTC)[reply]

@Cornelius Fyla: - I don't know what the 9 radii are about, that edit was by an anonymous IP. As you can see in this animation there are indeed infinite orbits at constant Boyer Lindquist r (although in the cartesian projection with R those are ellipsoid) since all photon orbits have constant r, while there are 2 (pro- and retrograde) in the equatorial plane (those have constant r and R). Those are the 2 orbits between which all the other orbits are, with emphasis on "between", but I have no idea where the number 9 comes from, and if the IP was serious or just trolling. I suspect the latter, since I never heard of that before, that statement doesn't even make sense mathematically since "between" only works with 2 radii, r_min and r_max. Maybe he confused somethig about the 3rd kind orbits inside the inner horizon (which is suspected to be unphysical, and inside of which the r_0 mentioned in the article is when a<m), then we have more, but still not 9. --

❇ 20:30, 2 August 2025 (UTC)[reply]