465
wat (thelemmy.club)
you are viewing a single comment's thread
view the rest of the comments
[-] starman2112@sh.itjust.works 29 points 23 hours ago

Preemptive explanatory note: the speed of light, approximately 300,000 km per second, is the highest speed that something can move through space.

The expansion of space doesn't happen at a set speed. It happens at a rate of approximately 70 km per second per megaparsec. So if you're measuring two points half a megaparsec away from each other, then every second, the space between them grows by about 35 km. If you're measuring two points 2 megaparsecs away from each other, then every second, the space between them grows by about 140 km.

If you're measuring two points 4300 megaparsecs away from each other, then the spacetime between them grows by about 300,000 km every second. That's not to say that anything is moving at 300,000 km per second, there's just more space between them every second

[-] vivalapivo@lemmy.today 4 points 11 hours ago

just more space between

Space out of thin air... tell me, mate, can I sell it?

[-] rumba@lemmy.zip 3 points 9 hours ago

NFT's sold, so probably yes

[-] starman2112@sh.itjust.works 20 points 22 hours ago* (last edited 22 hours ago)

Wtf is a megaparsec? It's a million parsecs. Tf is a parsec? A parallax arcsecond.

...Tf is a parallax arcsecond?

An attempt at an explanation for the layperson

Imagine you're standing outside. In front of you is a tree and behind that on the horizon is a mountain. You move 10 ft to your left, and the tree looks like it moved to the right, but the mountain looks like it hasn't moved at all. That's parallax. The closer something is, the more it appears to move when you move.

Imagine you are the pivot point on a big protractor. Your field of view can be divided into 360°. Every degree can be divided into 60 parts, called arcminutes. Every arcminute can be further divided into 60 arcseconds. Each arcsecond is 1/3600 of a degree.

How do these fit together? There's one more thing I need to explain.

The earth orbits the sun at around 149.6 million kilometers. That's called an Astronomical Unit. A parsec is the distance that an object would have to be, so that moving one Astronomical Unit would make it appear to shift sideways by 1 arcsecond.

Fraser Cain did a better job explaining, because he can use pictures

It's 3.26 lightyears.

[-] LovableSidekick@lemmy.world 3 points 22 hours ago* (last edited 22 hours ago)

Beautiful! That's the kind of perfect explanation I was trying to come up before giving up and just saying the expansion doesn't have a speed because it isn't motion, which is only partially correct lol.

[-] niktemadur@lemmy.world 3 points 22 hours ago

This guy expands!

this post was submitted on 25 May 2026
465 points (98.3% liked)

Memes

15932 readers
1421 users here now

Post memes here.

A meme is an idea, behavior, or style that spreads by means of imitation from person to person within a culture and often carries symbolic meaning representing a particular phenomenon or theme.

An Internet meme or meme, is a cultural item that is spread via the Internet, often through social media platforms. The name is by the concept of memes proposed by Richard Dawkins in 1972. Internet memes can take various forms, such as images, videos, GIFs, and various other viral sensations.


Laittakaa meemejä tänne.

founded 3 years ago
MODERATORS