Expanding universe

[breaca]

Anyway, interferometry is very precise and efficient. We don't need to reach the 70 km/s. We can go much slowier and just measure the little shift.

Thx for introducing me to interferometry

I thought that might be inferiometry!

[LeonWalras]

We know red shift isn't just red light because we see absorption lines from common elements in the universe, which have a very specific spectra, shift towards the red. Spectroscopy is pretty much the foundation of modern astronomy.

[Octavious]

Would not the shit towards the red caused by good old-fashioned velocity look indistinguishable to the shift to red caused by cosmic expansion?

[CptMike]

Would not the shit towards the red caused by good old-fashioned velocity look indistinguishable to the shift to red caused by cosmic expansion?

Yes. It is not distinguishable from red shift due to movement. But The Red Shift occurs in absolutely any direction that you look at, is even faster than the emiting source is far away, and there is no blue shift observed...

So there are 2 explanations:
* the universe expands itself
* the universe fears Trump and all stars try to escape themselves from Earth... Why even faster than they are far away and not the contrary ? That's due to the Trump Tower gravitational force that counters their flee.

[LeonWalras]

Andromeda is known to be full of racists.

[Crazy Anglican]

Andromeda is known to be full of racists.

Androgynous isn't though. Pretty liberal bunch there.

[Mercy]

Andromeda is known to be full of racists.

Is that why it is the only galaxy moving towards us?

[CptMike]

Andromeda is known to be full of racists.

Is that why it is the only galaxy moving towards us?

Let's make Milky Way great again !

[thedipplayer]

Andromeda is known to be full of racists.

Is that why it is the only galaxy moving towards us?

Let's make Milky Way great again !

What an excellent ad.

[jason4747]

"They say the universe is expanding. That should help ease the traffic."

-- Steven Wright

[MajorMitchell]

I think there is a prediction that the Andromeda Galaxy will start to collide with the Milky Way Galaxy in a few billion years time

[CptMike]

I think there is a prediction that the Andromeda Galaxy will start to collide with the Milky Way Galaxy in a few billion years time

In 4 billons of years and the process should take around 3 other billions of years to be completed. [ Note it is not expected to be a "destructive" collide but just a merging. ]

[Octavious]

Does anyone else think those numbers feel wrong? The age of the universe is supposedly under 14 billion years, and the Milky Way - Andromeda event will be done in 7? You'd imagine that the collision/merger would be a tiny fraction of the age of the universe, not a huge chunk of it. What mechanism put us on a collision course so quickly?

[CptMike]

Andromeda is approaching us at a speed of 110 km/s ie 0.00037 Light.Year / year. It is at about 2,500,000 Light.Years from the center of the Milky Way.

2,500,000 / 0.00036 = 7.5 billions of years so that both centers coincide.
They will collide sooner.

See Andromeda-Milky Way collision. There is also a video with a simulation of the collision.

[CptMike]

The second part of your question is "how can this happen that fast" ? After the big bang, matter started to gather with gravitional force, creating stars and galaxies and also giving impulsions/speed to this matter. Why could not this influence movements so that such "big masses" as galaxies tend to attract each other and/or be directioned one towards the other...

[Octavious]

I don't think you appreciate the point I was making. The narrative of the universe is one of great age and vast distances. The sun rises and sets on the Earth in much the same way is it has done many billions of times before, the Earth has orbited the Sun billions of times... everything has an overwhelming sense of permanence. It has a start and an end, but they are so far away it feels more like infinity than infinity does.

And then you up things to a galactic scale, and the galaxy has barely 50 rotations under it's belt and another galaxy is about to collide in another 20. The feeling is less one of infinity and more akin to watching a glass halfway between being pushed off the table and hitting the floor.

[CptMike]

Hi Octavious,

Yes. Sorry but I don't get your point...

However complex, with basic mathematics, the Babylonians and Egyptians were predicting when moon eclipses or floods of the Nil would occur.

I have done nothing more. If we know at what speed two objects go towards each other, it is not hard to calculate when they meet.

[LeonWalras]

It's a big deal, but it's not the first such collision. The Magellanic Clouds are small galaxies currently in the process of colliding with the Milky Way, and there's compelling evidence that some of the largest globular clusters orbiting our galaxy were once the cores of their own galaxies. The universe is a dynamic place. This kind of thing happens all the time.

[Octavious]

That's the point, Leon. It doesn't happen all the time because there hasn't been the time for it to happen. Two decent sized neighbouring galaxies will start to collide in around four billion years, which is around a third of all the time that's ever existed.

Mike talks about predicting lunar eclipses. Yeah, you can easily predict the next lunar eclipse, and with careful calculation can make a decent stab at predicting the next God knows how many thousands of eclipses into the future and in the past, because in those scales nothing really changes. Scale up to galactic collisions and you can predict this one will be done in around 7 billion years, and you can have a stab at predicting another, but you can't map things back thousands of times because after just two of those 7 billion year periods you don't have a universe anymore.

That's what I'm saying. At that scale the universe is a very different beast, yet our instinct is to treat it like we treat events in our solar system.

[MajorMitchell]

Does God know about this stuff Octavious our Oracle ? There's no guidance on co~mingling Galaxies in either the Bible ( Catholic, Protestant or Mormon ) or Koran. Maybe those heretical Scientologists have some Divine advice on the topic ?