Comment on Know your place
ininewcrow@lemmy.ca 21 hours ago
Here’s the galaxy and our approximate location in this system. To give you an idea of scale … the galaxy is estimated to be about 100,000 light years across. Meaning that if you could travel at the speed of light (which is impossible), it would still take you 100,000 years to cross the galaxy from edge to edge.
Here’s another perspective … this is local galactic group. Our nearest galactic neighbor is the Andromeda Galaxy … it’s located about 2 million light years from us. Again, if you could travel at the speed of light (which is impossible), it would still take you 2 million years to get there.
Another way of thinking of it is that the light we see from Andromeda today started it’s journey when our first prehistoric human ancestors first evolved in Africa 2 million years ago.
If you could travel at the speed of light, the only tim it would take you is the time spent speedign up and slowing down. Traveling at the speed of light stops the time for you.
It gets messed up really fast tho … so if you travelled at the speed of light 2 million light years to Andromeda and it only felt like a few minutes to you … then you travelled back 2 million light years back to our galaxy and it only felt like a few minutes to you … wouldn’t 4 million years have passed at your start point while you were gone?
Yup, but it's not felt like, it's how much time really passed for you.
Another one I've always liked; suppose two people (or space ships, whatever) are together in the empty space between galaxies. One of you gets a boost from an external actor, and travels 10 lightyears away at the speed of light. After that, the other one gets the same boost and joins the first. So for both, ten years have passed. But, without an external reference, there is no way to know which one moved first.
Epic Spaceman on Youtube had a great scale realization method. If out galaxy was the size of the United States, our solar system would be somewhere around the city of Denver. The neighborhood stars we can individually see with our eyes would be the area of the Denver city lights. The Sun would be the size of a red blood cell, and the solar system's expanse would be the size of a fingerprint.
I always loved those examples that show the scale of planets, stars and systems. I remember years ago before I got on the internet (yes I’m that old), reading a comic or book, I can’t remember where … all I remember is the cartoon and illustration.
If you made a scale model of the galaxy and fit it in between the earth and the moon … our sun would be the size of a marble and it’s nearest neighbour would be about a mile away. And some of the largest stars would be about the size of an average office building.
The problem is that the human mind can't easily grasp the whole thing at one time, or some parts of the scale aren't relatable enough. Like in your example, we know the Earth-Moon distance is huge abstractly but can't hold it in our mind like we can the marble and building, or even a mile distance, as those we can see. Or in The Epic Spaceman one, all we can understand is that the US is a very large expanse of land and yet our system is small even at that scale. But we can't put the two together easily.
When one gets that brief moment of awareness, it's both awesome and frightening. The last time it happened to me out of the blue was as a kid, looking up at a dark sky with a meteor shower. For a second I had the sense not of looking up at the sky with meteors falling, but of the reality of being on the surface of a rock that was flying around running into a debris cloud. And if I'm in a dark sky area and look long enough at the dense star field I can almost feel the sense of insignificance.
The problem is that the human mind can’t easily grasp the whole thing at one time
No, that’s just you.
Same here … I had those moments of awareness several times when I was a kid learning about all this stuff in school. Together with my background as an Indigenous Canadian (I’m full blooded Ojibway and it’s my first language before English) I was always taught by my elders to stay aware of my place in the universe and existence.
We lived in remote northern Ontario away from cities and towns and the sky was always a deep dark expanse, especially on a moonless night. One of the greatest spectacles I ever witnessed was heading out on the winter ice road near Moosonee on James Bay. My friends and I drove out for fun several miles north for fun. It was February and it was a frigid minus 40, no wind, no clouds, the air perfectly still. We stopped at a bit of a rise in the frozen mushkeg where there were no trees. The sky was so dry, so clear and so unobstructed by anything in the air that we could see every star down to the horizon. At that moment, for an instant realized I wasn’t looking up … I was looking at the universe from the edge of a sphere … it was almost dizzying because if I thought about it too long, I felt as if I were on the edge of a cliff ready to fall off.
How do you know where I am?
Out of 2 trillion galaxies that we know of? … it was a lucky guess.
Yes, it’s the unfashionable western spiral arm. We get it.
"If you've done six impossible things today, why not round it off with breakfast at Milliways!"
Meaning that if you could travel at the speed of light (which is impossible), it would still take you 100,000 years to cross the galaxy from edge to edge.
It’s just highly improbable to cross the galaxy in less than 100 000 years. You just need a device which generates infinite improbability and that’ll pass you trough every single point in the universe simultaneously and you can just stop where needed. Side effects may apply.
now imagine how insanely long it would take for any extraterrestrial species to fly through all that and meet us. that might explain why we haven’t met any of that yet.
zea_64@lemmy.blahaj.zone 21 hours ago
100000 years from an outside perspective, but because of time dilation you could make it take arbitrarily little time from your reference frame.
School_Lunch@lemmy.world 20 hours ago
I liked the character’s from Project Hail Mary perspective. The fact that we experience less time the closer we are to the speed of light is almost like an invitation to explore the stars.
Another things that gets me is the time experienced by black holes. We would think of the black hole at the center of the galaxy as some enduring, permanent thing, but with so much gravity, from the black hole’s perspective it may only exist for a fraction of a second.
ininewcrow@lemmy.ca 21 hours ago
I don’t fully understand how the science and theory works around all that … all I understand is that it is so unbelievably far away that in order to cross any of those distances or even think about crossing those distances, it begins to break our normal understanding of speed, distances and time.
Rhaedas@fedia.io 19 hours ago
Go Incredibly Fast
Another great example of both scale and speed. Even the near stars are far.