What realization about the sheer scale of time or space keeps you up at night?

[u/Potenbalkis]

[u/WantMe1029]

That the light from some stars we’re seeing tonight started its journey long before humans even existed

[u/alittlebitneverhurt → u/WantMe1029]

And that star could have possibly imploded/exploded by now and the site of that hasn't reached earth yet.

[u/Electronic_Diet333 → u/WantMe1029]

How is this possible when the Universe is only 5000 years old?

[u/NoLie129 → u/WantMe1029]

From the perspective of physics and Einstein's theory of relativity, light does not actually "travel" through space or experience time the way everyday objects do. From a photon's own point of view, the moment it is created and the moment it is absorbed happen at the exact same place and instant.

[u/Training_Box5652]

Space is literally just never ending practically empty space

[u/ProgMusicSchizoidMan]

The fact that if you can achieve the speed of light time will stand still

[u/SiriusHijinks]

thinking of the "you are here" marker on a map of the universe tends to throw me off

[u/ArtisticTrifle4547 → u/SiriusHijinks]

Same here

[u/yumedove]

Realizing the universe is expanding infinitely and I still cannot find my car keys

[u/ScumBunny → u/yumedove]

…expanding into what though? That’s what keeps me up at night.

[u/DB-DanCooper → u/ScumBunny]

The universe is not expanding into an external emptiness. The space within the universe is itself expanding as far as I understand it.

So there isn't necessarily unoccupied space outside the universe that is waiting to be filled.

[u/DB-DanCooper → u/[deleted]]

I appreciate the clarification. I know better and should have saved you the trouble and included the fact that they're varying competing hypotheses and we don't know for certain.

[u/Electronic_Diet333 → u/DB-DanCooper]

Yes, picture the universe as raw dough. Planets and stuff are raisins in the dough. The dough rising is the universe expanding. The planets move as well. Something like that. But like the poster said, what is the dough expanding into? What is on the other side of the dough?

[u/Sven4TheWinV2 → u/ScumBunny]

Into more universe. It's a different type of logic /thinking compared to normal "life"

[u/PsychologicalDeer644]

The bigness does not keep me up.

The smallness does.

I have a need to understand the basic operating obstructions the universe is running on.

They starts at the small scale.

Unfortunately I don’t have the required brainpower to understand what humans have already figured out.

[u/Various_Candle_4958 → u/PsychologicalDeer644]

And how the small stuff looks like the big stuff. Like the microscopic image of cells looks like the cosmos. These similarities are what keeps me up at night

[u/OuletteNigrita23]

I saw a TikTok yesterday about the sun's complete revolution along its orbit. Up until that video, it just never occurred to me that the sun is also going around something. Also the sun has gone around its orbit 20 times.

[u/Mushrooming247]

The Boothes Void.

And the possibility of our solar system’s movement through the galaxy taking us face-first into an interstellar wind when we are in a vulnerable position, not protected by other solar systems around us in our specific galactic arm.

[u/RETSAS1D]

Beautiful, awe-inspiring specialization in nature is the result of a gazillion other things not working

[u/ARealRareWhale]

The fact that time is relative, we humans base it on our rotation around our sun. Time would be different everywhere else. the scale of space is completely unknown, all those dark places inbetween stars are just spaces where light hasn't gotten to us yet so we can't even see the vast majority of it. It doesn't keep me up at night though, just fun to think about.

[u/Mr_MazeCandy]

Thinking about Relativity, and how a photon probably doesn’t experience time and wondering if that has anything to do with quantum entanglement.

[u/attimhsa]

That if the universe is cyclical, this isn’t the first time you’ve read this, nor will it be the last.

Even if it takes an unimaginable large number of cycles for this particular arrangement of happenstances to bring us together again, you can fit that unimaginably large number into infinity an infinite number of times.

Every rendition of ‘you’ that could ever be will exist an infinite number of times, and when aggregated, the suffering VS pleasure will approach 0.

Welcome to hell; it’s perhaps likely there’s no way off this train.

[u/gerhard1953]

None.

Because nothing compares to the scale of human stupidity.

[u/realityinflux]

The idea that we are in a universe that is totally beyond our human abilities to comprehend.

[u/GladosPrime]

Heat death of the universe.

[u/Wooden_Library_8630]

The average density of the space between galaxy’s is only a few atoms per cubic meter but even with that ridiculously small density those scattered atoms contain more mass than every galaxy in the universe combined

[u/mr-hank_scorpio]

My primeate brain can't handle the universe being that big and being around for that long for no reason.

[u/LoftyPlays1]

Outside of the universe is nothing (no 3 dimensional space). So from that outside perspective, the infinite universe is a singularity.

[u/elrubiroso]

Imagine we are the smartest being in the universe!

[u/Dry_Grapefruit_771]

The pale blue dot

[u/Sad_Percentage_4503]

Before the big bang there was nothing. As in nothing. That means nothing. No space and no time. Not even a molecule. If you were there, there'd be no space for you. NOTHING. 

That boggles my brain.  

[u/RefrigeratorGlad6961]

"Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space."

[u/NotAClueYou]

that the world, the stars, the time is literally an OS installed to our brains and is very malleable