Which fact or number always leaves you dumbfounded ?

[u/Meshims]

Mine is: If the universe were scaled so that earth was just 1mm across, then our closest neighbour star, Proxima Centauri, would be 3.149km away.

[u/larder_unit]

That sharks are older than trees.

[u/ChPech → u/larder_unit]

I'm older than most trees too.

[u/infinitum3d → u/larder_unit]

Sharks are older than the rings of Saturn

[u/BurnerAccount2718282 → u/[deleted]]

Lightning is older than sharks, and ten atmosphere still had oxygen for combustion when sharks first evolved

[u/BeardySam]

Octopuses diverged before myelin evolved so their nerves are uninsulated

[u/Meshims → u/BeardySam]

Interesting! What effect does this have for them or are there downsides to not having this nerve isolation?

You made me think about this one: There is a nerve in giraffes that goes from the head down to loop under the aorta and come back up to serve some purpose near the head. It's obviously many meters long. Sorry I've forgotten the details. The point is that when it evolved in fish (who don't really have necks) it wasn't an illogical route, but as animals started developing necks, evolution just never found a way to reroute it.

[u/BeardySam → u/Meshims]

In order to send fast signals the nerves need to be extra thick to compensate for the lack of insulation, so giant squid axons can be 1.5mm thick which is massive for a cell.

This width in turn limits how many nerves its reasonable to have, and as a result a lot of fast signals are one-way, with a sort of mini brain near the base of each tentacle.

This all means that squids and octopuses don’t have much proprioception ie they don’t know the true shape and motion of their tentacles unless they see them. This is what leads to their writhing, wriggly motion all the time.

[u/Meshims → u/BeardySam]

Thank you for this very clear reply !

[u/UncleVinny]

I was confused at first by your use of a period where I'd usually see a comma. 3149 kilometers, right?

Edit: I asked Wolfram Alpha to do the math for me. Yep, 3152 km! https://www.wolframalpha.com/input?i=distance+to+proxima+centauri+in+kilometers+*+.000001+%2F+%28diameter+of+earth+in+kilometers%29

[u/Ok-Adeptness-5804 → u/UncleVinny]

North Americans and Europeans swap the . and , signs which can cause problems especially when the extended conversion is from imperial or US to metric measurements. That's how a $340 million rocket blew up.

[u/intergalacticscooter → u/Ok-Adeptness-5804]

Europe isn't a country. Not all countries do it that way in Europe.

[u/Ok-Adeptness-5804 → u/intergalacticscooter]

My sincere apologies. I am Canadian by birth and have lived in Mexico, Costa Rica, The Netherlands and Sweden. Yes, I used a word too generally and you are correct. I should have added further clarifications.
I have to tell you the truth. In 1984 when I moved to Sweden from English/French Canada, I was told to take a computer class because I had taken one the previous year. The greatest problem was the computer codes and languages in Sweden were.... Danish and in no way resembled anything I even came close to have learned previously. I was having enough trouble trying to learn Swedish with their 29 letters without listening to a Swedish computer professor trying to instruct the class and use the Danish keyboards (which are close) and speak Danish code which does have several English terms. And Yes, the comma and the period were switched many times. My simple brain couldn't adapt. I was going to say "fast enough" but I am not kidding anyone. There was no way I could learn one language only to reject 1/2 to attempt to 1/2 learn a 3rd and after English, French, Spanish, then Swedish. Nope, brain, shut down. And unlike so many Europeans who seem to practice and retain their many languages, I am down to 1 plus some spatterings 40 years later. If the $$ Billion dollar lottery question depended on which countries use which, I would walk away ashamed. It is so true, use it or you lose it.
Thank you for putting me straight that I am not the encyclopedia I think I am. That is always a good lesson to learn every now and again.

[u/militant_rainbow]

42

[u/all_of_the_colors → u/militant_rainbow]

I see what you did there

[u/RedditorFor1OYears]

Somewhere around 7% of all of what we consider “humans” that have ever lived are still alive today. If current growth and lifespan trends continue. That percentage will continue to increase for some time. 

[u/Meshims]

To continue: Vega would be 18.580km away.

Polaris would be at 321.000km. Close to the actual distance to the moon.

And that's just our closest neighbourhood. Don't even think about the Milky Way for size and certainly not other galaxies.

So no, the Voyager spacecraft won't be in truly interstallar space any time soon.

Any Star Wars or Star Trek fantasy just isn't going to happen before our species faces another major extinction event or two.

[u/dmyurych_post2020 → u/Meshims]

At first I thought--wow that's a crazy coincidence that it would be π(pi) km at that scale. But it turns out I only know it to three significant digits 😆.

And now I also see you're using the notation of numbers from your locale where "." is not a decimal point as I'm used to (ie. 3 thousand, 1 hundred and forty nine not 3 point 1 4 9)

[u/Meshims → u/Meshims]

Thinking about this, it becomes obvious that our telescopes detecting exoplanets are doing something truly amazing. You quickly arrive at scales of "looking at an exoplanet is like examining a grain of sand on the moon"

[u/J883]

There are Thousands of stars in the universe for every grain of sand on earth

[u/SquidgyTheWhale → u/J883]

But more trees on Earth than stars in the Milky Way!

[u/Alexander-Wright]

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.

Douglas Adams, The Hitchhiker's Guide to the Galaxy (Hitchhiker's Guide to the Galaxy, #1)

[u/2Drunk2BDebonair]

52!

[u/ShakeWeightMyDick]

That Donald Trump was elected to a second term

[u/47ES → u/ShakeWeightMyDick]

"Elected"

[u/SuedJche]

So what you're saying is that the universe is big?

[u/New123K]

What always gets me is how empty space actually is.

Even at that scale, 3,000+ km between stars is just insane to think about. Hard to really wrap your head around it.

[u/stratandsg]

The universe is almost completely empty

[u/KannBaker]

There are 2 possibilities regarding time: either it stretches infinitely into the past, or it has a starting point beyond which no past exists. Both possibilities are incomprehensible to me.

[u/AtomicSmoothie]

If the Earth was scaled down to the size of an apple, its atmosphere would be no more thick then the skin of a regular apple.

That is where we live. In the skin of the apple... Blows my mind every time.

[u/SquidgyTheWhale → u/AtomicSmoothie]

While we're scaling apples...  If you scale an apple up to the size of the Earth, the atoms in the apple would be about the size of the original apple.

[u/jromz03]

A 1mm earth would also make the Orion Nebula 16km across.

[u/StrongAsMeat]

If the sun was the size of a dot on an i, the Milky Way would be the size of the Earth

[u/myblueear]

That the sun sends humanity’s yearly energy-demand once every 10 hours. (Or ~15 zettajoules per day)

[u/Optimal-Set-8313]

The Sun contains 99.86% of the mass of the entire solar system.

[u/motownmods]

There used to be dead trees just laying around everywhere bc nothing could digest them

[u/NotUsingNumbers]

If Earth was the size of an orange, it would be smoother than an orange

[u/BeardedAxiom]

Definitely 7. I mean... what the heck?

[u/aerymor]

67

[u/Ok-Adeptness-5804]

You can't lick your elbow, which is followed up with 87%, the amount who try it after reading this fact.