Expanding universe

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breaca
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Re: Expanding universe

#21 Post by breaca » Sat Jun 30, 2018 4:22 am

Maniac wrote:
Fri Jun 29, 2018 8:35 pm
CptMike wrote:
Fri Jun 29, 2018 7:54 pm

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!

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Re: Expanding universe

#22 Post by LeonWalras » Wed Aug 01, 2018 10:24 am

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.

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Re: Expanding universe

#23 Post by Octavious » Wed Aug 01, 2018 10:49 am

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

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Re: Expanding universe

#24 Post by CptMike » Wed Aug 01, 2018 7:25 pm

Octavious wrote:
Wed Aug 01, 2018 10:49 am
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.

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Re: Expanding universe

#25 Post by LeonWalras » Wed Aug 01, 2018 8:39 pm

Andromeda is known to be full of racists.

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Re: Expanding universe

#26 Post by Crazy Anglican » Fri Aug 03, 2018 10:23 pm

LeonWalras wrote:
Wed Aug 01, 2018 8:39 pm
Andromeda is known to be full of racists.
Androgynous isn't though. Pretty liberal bunch there.

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Re: Expanding universe

#27 Post by Mercy » Sat Aug 04, 2018 2:26 am

LeonWalras wrote:
Wed Aug 01, 2018 8:39 pm
Andromeda is known to be full of racists.
Is that why it is the only galaxy moving towards us?
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Re: Expanding universe

#28 Post by CptMike » Sat Aug 04, 2018 8:03 am

Mercy wrote:
Sat Aug 04, 2018 2:26 am
LeonWalras wrote:
Wed Aug 01, 2018 8:39 pm
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 !

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Re: Expanding universe

#29 Post by thedipplayer » Sat Aug 04, 2018 8:06 am

CptMike wrote:
Sat Aug 04, 2018 8:03 am
Mercy wrote:
Sat Aug 04, 2018 2:26 am
LeonWalras wrote:
Wed Aug 01, 2018 8:39 pm
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.

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Re: Expanding universe

#30 Post by jason4747 » Sat Aug 04, 2018 2:07 pm

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

-- Steven Wright

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Re: Expanding universe

#31 Post by MajorMitchell » Sun Aug 05, 2018 5:46 am

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

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Re: Expanding universe

#32 Post by CptMike » Sun Aug 05, 2018 10:25 am

MajorMitchell wrote:
Sun Aug 05, 2018 5:46 am
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. ]
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Re: Expanding universe

#33 Post by Octavious » Sun Aug 05, 2018 11:55 am

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?

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Re: Expanding universe

#34 Post by CptMike » Sun Aug 05, 2018 12:21 pm

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.

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Re: Expanding universe

#35 Post by CptMike » Sun Aug 05, 2018 12:28 pm

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...

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Re: Expanding universe

#36 Post by Octavious » Sun Aug 05, 2018 5:21 pm

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.

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Re: Expanding universe

#37 Post by CptMike » Sun Aug 05, 2018 7:54 pm

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.

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Re: Expanding universe

#38 Post by LeonWalras » Mon Aug 06, 2018 4:51 am

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.

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Re: Expanding universe

#39 Post by Octavious » Mon Aug 06, 2018 8:30 am

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.

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Re: Expanding universe

#40 Post by MajorMitchell » Thu Aug 09, 2018 6:21 am

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 ?

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