What is the Universe expanding into..

Do you think there was anything before the big bang?

  • I don't think there was anything before the Big Bang

    Votes: 56 12.5%
  • I think something existed before the Big Bang

    Votes: 200 44.7%
  • I don't think the big bang happened

    Votes: 54 12.1%
  • I think the universe is part of a mutiverse

    Votes: 201 45.0%

  • Total voters
    447
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Disco-Pete, the Scientific method is to state your references! Otherwise we are guessing!

I have listened to the occasional John Fogerty album.

To my surprise, he wrote "Proud Mary". I would have swore Ike Turner did it.

But nobody did it like Tina:


BTW, and not many people know this. But when you hold up your right hand... Well that is Gospel.
Had I known obfuscation is your preference, I would have. :spin:

however, my apologies. :oops:

"to your surprise"? Oh my goodness you've led a (cloistered) sheltered life?
 
In this thread, we obey the laws of thermodynamics! :judge:
 

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Back to Quasars. Seems most of the really big ones we are seeing are from the first 1-3 billion yrs of the universe's existence, although the closest one is 600m LY away - so a bit of an outlier.

One of the largest, 3C 273, is so powerful that if the solar system was placed 234 LY from its centre, it would be as bright as the mid day sun. These objects are trillions of times more powerful than the sun - of the order of 10^40 watts vs c. 3.8 x 10^26 watts from the sun.

A lot of these quasars are clustered into huge structures, so the prevailing thinking is they were formed when the universe was very young and there was plenty of matter to create the monstrous BH that are at the heart of quasars. It is likely that, as mentioned in the post by Galu, that by now they would have swept up most of the matter around them and are dormant - so we are seeing them as they were 10-13 billion years ago.
 
Back to Quasars.

Quasars are active galactic nuclei which are among the brightest objects, and therefore the most distant, we can see.

They are so bright, that they are visible at a distance of many billions of light years.

Because they are so far away, quasars serve as excellent fixed points in the sky, allowing a pair of radio telescopes (one in Europe and one in the USA) to triangulate the distance between Europe and the USA.

By this means we can determine that Europe is moving away from the USA at the rate of 2.3 cm per year, which is the speed at which fingernails grow.

Satellite laser ranging and GPS measurements give compatible results.
 
3C 273 ... the prevailing thinking is they (quasars) were formed when the universe was very young

Quasar 3C 273 lies at a redshift of 0.1583, but this is peanuts compared to the 11.1 redshift of galaxy GN-z11.

GN-z11 is so far away that it existed a mere 400 million years after the Big Bang, or about 13.3 billion years ago.

GN-z11 is not a quasar, but is bright enough to be visible to Hubble because it is forming stars at 20 times the current rate of the Milky Way.

This farthest galaxy is probably representative of the first generations of stars to form around black holes.

https://www.space.com/32150-farthes...,the Big Bang, 13.8 billion years ago (right).
 

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Sagittarius A* eventual jets points to us :-/

There is a possibility of a TDE (Tidal Disruption Event) at the heart of the Milky Way galaxy - see Bonsai's link below.

https://astronomy.com/magazine/news/2021/12/how-do-black-holes-swallow-stars

A TDE occurs when a star is catapulted by gravitational perturbations directly towards a supermassive black hole.

The doomed star gets violently ripped apart in a matter of just a few hours, producing a highly energetic and luminous flare.

A TDE is so bright it can resemble a supernova, but such events are rare. Astronomers estimate that a TDE occurs in a galaxy the size of the Milky Way no more than once every 100,000 years, whereas a supernova occurs within such a galaxy roughly once a century.

Bonsai's link refers to Swift J1644+57 which was an unusual TDE in that it was over 10,000 times more energetic than normal thanks to its relativistic jet.

Judging by the rarity of TDEs in general and ones like Swift J1644+57 in particular, I think the chances of us here on Earth being in danger are remote indeed.
 

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