Galaxies or black holes

[Brainee]

Michio Kaku says that certain bodies that look like galaxies are black holes. How can this be?

[iNow]

A full quote and some context would help. Sounds to me like you misheard / misread him, but he says all kinds of whacky shit while trying to popularize science so anything’s possible. 

Most galaxies seem to have supermassive blackholes at their center. 

[Brainee]

It is shown at youtube at https://youtube.com/watch?v=F5F48ZviBzs

[iNow]

What timepoint?

[Brainee]

7 minutes ago, iNow said:

What timepoint?

He shows pictures of the galaxies or black holes early on in clip then says they are black holes later on.

[mistermack]

He says that it takes billions of years for a galaxy to form. I don't know where he gets that from. I'm not an avid student of cosmology, but what drips of information I have absorbed described galaxies forming very soon after the big bang. And mostly, or all, with supermassive black holes at the centre. 

He seems to be talking about what people thought 25 years ago. Obviously the James Webb is showing some unexpected stuff, that's what it's for. Before Webb, it was more speculation what the early universe looked like. 

52 minutes ago, Brainee said:

He shows pictures of the galaxies or black holes early on in clip then says they are black holes later on.

It seems to be emerging that all, or nearly all galaxies have a supermassive black hole at the centre, and the way that they detect that is by gravitational lensing. This isn't new stuff, it's what people have been saying for ages. Maybe the James Webb is showing that that's true for the very earliest galaxies. I haven't heard that there was any theoretical reason why that shouldn't be the case.

[Airbrush]

On 4/13/2023 at 10:19 PM, mistermack said:

He says that it takes billions of years for a galaxy to form. I don't know where he gets that from. I'm not an avid student of cosmology, but what drips of information I have absorbed described galaxies forming very soon after the big bang. And mostly, or all, with supermassive black holes at the centre. 

He seems to be talking about what people thought 25 years ago. Obviously the James Webb is showing some unexpected stuff, that's what it's for. Before Webb, it was more speculation what the early universe looked like. 

It seems to be emerging that all, or nearly all galaxies have a supermassive black hole at the centre, and the way that they detect that is by gravitational lensing. This isn't new stuff, it's what people have been saying for ages. Maybe the James Webb is showing that that's true for the very earliest galaxies. I haven't heard that there was any theoretical reason why that shouldn't be the case.

I just finished watching the OP Youtube.  Michio said that Web could see giant galaxies, as big or bigger than the Milky Way, far on the edge of our visual horizon, over 30 Billion LY away now.  We had expected to see only small galaxies.  We thought they would merge over time to produce the largest galaxies, taking billions of years.  But they were already giant near the beginning.  This suggests maybe the direct collapse model of formation of supermassive black holes.  They were supermassive near the beginning, suggesting they formed in a different way.  Shortly after the big bang some giant clouds of gas were so spherical in shape that when they collapsed, they skipped star formation, and were born supermassive.

"Distant and early supermassive black holes, such as J0313–1806,^[40] and ULAS J1342+0928,^[41] are hard to explain so soon after the Big Bang. Some postulate they might come from direct collapse of dark matter with self-interaction."

Supermassive black hole - Wikipedia

 

Edited April 19, 2023 by Airbrush