this post was submitted on 06 Jul 2026
1390 points (99.0% liked)
Technology
86145 readers
3896 users here now
This is a most excellent place for technology news and articles.
Our Rules
- Follow the lemmy.world rules.
- Only tech related news or articles.
- Be excellent to each other!
- Mod approved content bots can post up to 10 articles per day.
- Threads asking for personal tech support may be deleted.
- Politics threads may be removed.
- No memes allowed as posts, OK to post as comments.
- Only approved bots from the list below, this includes using AI responses and summaries. To ask if your bot can be added please contact a mod.
- Check for duplicates before posting, duplicates may be removed
- Accounts 7 days and younger will have their posts automatically removed.
Approved Bots
founded 3 years ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
Hold out your hand flat, palm facing straight up. Now tilt it at any angle without going perpendicular to the ground, but let's just use 45 degrees for example.
With your hand tilted backwards just a bit, but still facing upward overall, look across the room and you can predict where you would need to squat down to see the palm of your hand even if you were on the ground.
This shows light can travel in a straight line from that spot on the ground to the palm of your hand even though your palm is still facing upward overall, albeit at an angle of 45 degrees (and there is a spot on the ground that works at any angle, but the spot is farther away if the hand is tilted less).