A place for majestic STEMLORD peacocking, as well as memes about the realities of working in a lab.
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This is a science community. We use the Dawkins definition of meme.
Milky Way is going to collide with Andromeda… over the course of millions of years, and due to the distance between stars and other objects the two galaxies are just going to merge with each other and very few things will actually make physical contact.
Well, if they collide (and merge), they'll also fling a lot of stars into the void, but we aren't too sure anymore that's actually gonna happen. NASA explains why (YT, 2:30min).
Thank you very much for posting the video length. I wasn't gonna watch a 10 minute video but 2 was short enough.
Nobody liked those stars anyway…
Eh, the odds of actually colliding with anything is low enough. Plus the night sky would probably be even more breathtaking. I'm in
I think there's maybe more risk with the solar system being thrown off balance with other gravitational forces pulling things out of orbit. Even if earth just gets pulled away from the sun a little we are screwed. Or even the moon pulled away from earth somewhat.
Even if earth just gets pulled away from the sun a little we are screwed.
I get what you're saying, but had to laugh at the use of "a little" here. The goldilocks zone in the solar system is roughly the between the orbits of Venus and Mars, and we're almost right in the middle of it, so "a little" is like 150 million km.
I would imagine that the first issue we would experience would be that the moon would be pulled out of Earth's orbit first and then we lose the ocean tides and the stable tilt of the earth. It would probably get worse from there.
Goldilocks zone is basically just where life can survive.
Even if we stay within the Goldilocks zone doesn't mean that most of the species alive today won't go extinct because it fucks up the seasons or the magnetic poles or tilt of the earth, etc.
Maybe we’ll get lucky and it’ll counter global warming
Just keep scooting away a little every year, problem solved
"Thank god global warming never happened."
"Actually, it did, but thank god for nuclear winter."
Could the other galaxy please pull us just the correct distance away from the sun to cancel the effect of global warming?
Given the vastness of space, this is a lot less likely than you might think, and the process itself would likely take millenia anyway.
It's even safer. The odds that it's coming directly at us to "collide" is low. Moving towards us doesn't mean it's moving directly at us. If you're driving down the road, all cars going in the other direction get doppler shifted. They're coming towards you, they pass beside you (hopefully), and then they're moving away from you.
So blue is moving toward you?
I was always a bit confused with the explanations in high school. But I also got a D in physics so maybe I'm just dumb.
Blue shift, it's moving towards you, the photons are being "compressed" to a higher, bluer frequency. Redshift, the light is being "stretched" to a lower, redder frequency. Both only noticeable at significant fractions of the spped of light, relativistic speed.
Something ominous about the post is that a cosmic object that is moving towards you at a steady rate is consided "blueshifted" in the past tense, it's velocity is steady. If a galaxy is "Blueshifting" in the present tense, then that galzy is somehow accelerating at you, which is impossible unless it's under direct control by an entity, presumably a kardeshev level 3 civilization.
Isn't the rate of expansion in the universe increasing, and at an uneven rate at that? Meaning it could just as easily be an as of yet unknown natural phenomenon?
The expansion is supposed to be happening everywhere at the same time, not just at the edges.
For example, tomorrow there should be more space between the Sol and Alpha Centauri systems than there was yesterday.
Our present understanding suggests that 'normal' universal expansion should not (in and of itself) result in anything moving towards us.
Aren't the milky way and andromeda on a collision course with each other?
Yep. Space is expanding everywhere at once, but the effect is minuscule at the scales we're used to. And even at galactic scales the "speed" of expansion might seem like a lot to us, but it still isn't enough to overcome the motion of objects. I looked up some rough numbers to give you an idea:
The rate of expansion of space is 73 km/s/Mpc. So for every 3.26 million light-years between you and a distant galaxy, the space between you and that galaxy is expanding by 73 kilometers per second.
Andromeda's blue shift indicates it's headed towards us at 110 km/s. And in my non-expert head I'm thinking that blueshifted light must have already been redshifted by the millions of years traveling through space to reach us. So the galaxy's speed through space towards us when the light was emitted was considerably higher.
Andromeda is 2.5 Million light-years away, btw. So the cumulative distance of space between here and there is expanding at something like 73 km/s/Mpc * 2.5 Mly * 1Mpc/3.26Mly = 57 km/s.
But when talking about relativistic distances and speeds, basic terms regarding time and location don't always make sense.
Milky way and Andromeda are close enough that expansion is too small to overpower gravity
Our local group is racing toward The Great Attractor but will never reach it as expansion is pulling it away faster than we're falling toward it
For example, tomorrow there should be more space between the Sol and Alpha Centauri systems than there was yesterday.
Galaxies are gravitationally bound, they do not expand in the same way as the universe.
Fair enough, I should have been thinking bigger.
Yes which would be very odd for a far away object
No, it's just depressed and that makes us feel sad and worried for it.
I'm blue shifting-daba-dee-di
Oh no! We might not survive the collision to hundred fifty thousand years from now!
If it's billions of light years away it might be just a little longer than that.
*must be
might take a little bit o' while. you got plenty of time to start that pot roast in the slow cooker.
check on it around 100,000 and give it a stir.
If it's blue shifting from that distance, then it's likely some advanced technology is moving it in our direction.
There's not many other explanations for that.
Could it potentially be an object orbiting around the cosmic center that just so happens to have an orbital path that crosses us?
I have to admit that astronomy is what caused me to change majors, but that's because I stopped going to class when the lesson was, "This is a terrestrial planet, it's rocky," and my first exam was like, "If it's 5:45pm in Tanzina on October 15th, how many degrees is the moon above the horizon?"
Had to do AM because it's below the horizon in the PM.
I really want you to know that I appreciate this.
Might be a dumb question, but if it's blue-shifting surely we wouldn't know it's far away in the first place? I thought the amount of redshift is broadly how we determine cosmic distances?
Armchair expert here
From my understanding blue and red shifting is mostly related to movement. Like when a firetruck run past you with sirens on, you can hear change in pitch when compared it moving towards you vs away from you.
It's a similar effect with galaxies, red shifting means that after the light was emitted the space between us has increased and the light kind of stretched out to longer wave.
Now anyone with more knowledge on the subject, please correct me.
You're missing the point that the universe is expanding uniformly. That means two points acceleration away from each other is dependent on their distance apart. The further they are from each other the faster they accelerate from each other.
So GP is right. We measure red shift and infer distance.
Yes, but everything red shifts "naturally" as well as the light travels because of the expansion of the universe. So something traveling towards us will still red shift, just slightly less so. To determine distance you have to use something called the cosmic distance ladder. It consists of known properties of stellar objects that we can measure to determine the distance of objects.
Now imagine if it did blue shift.
https://www.youtube.com/watch?v=opvuEVpl_PM&list=RDopvuEVpl_PM&start_radio=1
Yeah, I'm pretty sure red shift is our best method for getting distances on billions of light year distant objects, no idea of it's the only one at that range
ELI5?
If something is red shifting, it's accelerating away from you. If something is blue shifting, it's accelerating towards you. An entire galaxy accelerating towards you is somewhat concerning.
Redshift comes from relative velocity (and other effects), not acceleration. Andromeda's light is blueshifted as it's moving towards us, but it's not accelerating.
I was going to argue with this too, but the meme says blueshifting, not blueshifted. They're right, but mostly because the meme is probably written poorly. Maybe they meant it's accelerating toward us though. Idk.
On top of that, we've found that basically everything is redshifting as the universe expands. So to see a blueshifting galaxy would mean something potentially unnatural.
You know how the sound of things moving from you changes? Towards you the pitch is higher, away from you it is lower. The same happens with light. We know how some things should look like, so if they are more toward red or blue, we know their speed relative to us. Blue = towards us = "we will collide" (you also do not collide with every car with a siren where you hear that effect).
Humans in 200 years be like: ha ha warp drive go brr.