this post was submitted on 03 Mar 2024
118 points (96.8% liked)
Asklemmy
43945 readers
761 users here now
A loosely moderated place to ask open-ended questions
Search asklemmy ๐
If your post meets the following criteria, it's welcome here!
- Open-ended question
- Not offensive: at this point, we do not have the bandwidth to moderate overtly political discussions. Assume best intent and be excellent to each other.
- Not regarding using or support for Lemmy: context, see the list of support communities and tools for finding communities below
- Not ad nauseam inducing: please make sure it is a question that would be new to most members
- An actual topic of discussion
Looking for support?
Looking for a community?
- Lemmyverse: community search
- sub.rehab: maps old subreddits to fediverse options, marks official as such
- !lemmy411@lemmy.ca: a community for finding communities
~Icon~ ~by~ ~@Double_A@discuss.tchncs.de~
founded 5 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Ooh, this is new info. How so?
One way to look at it is loss of information. If you point a (brightness-tolerant) telescope at a lasar beam, you can't see much. Pretty much every beam is the same. If you point it at the sun there's all kinds of interesting features. Another way is to consider that light is a gas made of photons, and you're essentially talking about making every particle spontaneously align, which in a heat engine would obviously be ridiculous. All of these are entropy-negative processes, and a passive mirror or lens is passive and can only do reversible operations.
Another fun fact that comes out of this is that a magnifying glass can never make a spot hotter than the sun. Here's an XKCD what-if that goes into it - and might honestly be where I learned this first.