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Physics and astronomy thread

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3 minutes ago, Man of Constant Sorrow said:

1) I'm not sure - but I believe so. 

2) Depends on how much matter - even if constantly sucking. Hawking Radiation is always being emitted - thus, if too little matter, shrinkage will occur. 

To piggy back on this

1 - I agree.  I think all galaxies have a black hole at the center, as far as we understand it, but some galaxies have more than one.

2 - They do grow in size as they suck in matter, but between Hawking Radiation and other emissions (they can expel gas that will extend light years in length), they can also shrink.

 

One amazing thing about this picture is that this black hole is in a galaxy that's 54 million light years from Earth.

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13 minutes ago, Andy Dufresne said:

A couple n00b questions about black holes.

1) Are we pretty sure there are black holes at the center of EVERY galaxy? Thought I'd read that..?

2) If black holes are constantly sucking in matter, does that mean they're constantly growing in size?

1- Yes, that's what they think

2- It's not always sucking in new things, more like there is rotation around it, like planets around their star. Things do fall in and also, I think matter is ejected as well. I remember reading that it's thought there is a limit to how much mass they can have.

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3 minutes ago, RC94 said:

To piggy back on this

1 - I agree.  I think all galaxies have a black hole at the center, as far as we understand it, but some galaxies have more than one.

2 - They do grow in size as they suck in matter, but between Hawking Radiation and other emissions (they can expel gas that will extend light years in length), they can also shrink.

 

One amazing thing about this picture is that this black hole is in a galaxy that's 54 million light years from Earth.

One thing I don't understand that they I've never really seem explained is how that radiation that is ejected out escapes.  A black hole is so strong, it even pulls in light.  Yet a jet of radiation is spewing out of it. How?

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I’m on vacation and reading Stephen Hawking right now. This just about perfect timing for me

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That Black Hole picture looks like it could be the cover of a Tool album

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40 minutes ago, TheIronSheik said:

One thing I don't understand that they I've never really seem explained is how that radiation that is ejected out escapes.  A black hole is so strong, it even pulls in light.  Yet a jet of radiation is spewing out of it. How?

From what I understand, it's not really ejected from within the event horizon. 

Rather, it is produced when virtual particles are produced - an ever occurring event - so close to the event horizon, that one of the particles gets pulled in, while the other escapes. 

Once separated, the virtual particles can no longer recombine & thus, pop back out of existence. The new reality of the escaped particle = Hawking Radiation. 

Now, seeing that clearly & logically in my mind, is not easy, because on our scale, it still seems that the hole should still have gained mass. 

Measurements, seem to indicate otherwise. I wish I could understand it better, but I don't. 

Gllll

 

Oh - and, I'd love to have a real physicist explain it to me & point out where I may be wrong. 

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1 hour ago, Andy Dufresne said:

A couple n00b questions about black holes.

1) Are we pretty sure there are black holes at the center of EVERY galaxy? Thought I'd read that..?

2) If black holes are constantly sucking in matter, does that mean they're constantly growing in size?

it is believed that virtually all massive spiral/elliptical galaxies have a SMBH at the center.  But I think there are some smaller, irregular ones where they're not sure.

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1 hour ago, Andy Dufresne said:

“But Sauron was not of mortal flesh, and though he was robbed now of that shape in which had wrought so great an evil, so that he could never again appear fair to the eyes of Men, yet his spirit arose out of the deep and passed as a shadow and a black wind over the sea, and came back to Middle-earth and to Mordor that was his home. There he took up again his great Ring in Barad-dur, and dwelt there, dark and silent, until he wrought himself a new guise, an image of malice and hatred made visible; and the Eye of Sauron the Terrible few could endure.” 
― J.R.R. Tolkien, The Silmarillion

Me, I saw a Halloween glazed donut :shrug:

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1 hour ago, jamny said:

Yes, they showed the picture.

 

link

Black hole sun, won't you come..... and wash away the rain.

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7 minutes ago, Man of Constant Sorrow said:

From what I understand, it's not really ejected from within the event horizon. 

Rather, it is produced when virtual particles are produced - an ever occurring event - so close to the event horizon, that one of the particles gets pulled in, while the other escapes. 

Once separated, the virtual particles can no longer recombine & thus, pop back out of existence. The new reality of the escaped particle = Hawking Radiation. 

Now, seeing that clearly & logically in my mind, is not easy, because on our scale, it still seems that the hole should still have gained mass. 

Measurements, seem to indicate otherwise. I wish I could understand it better, but I don't. 

Gllll

 

Oh - and, I'd love to have a real physicist explain it to me & point out where I may be wrong. 

Followup after a Google :

"An alternative view of the process is that vacuum fluctuations cause a particle–antiparticle pair to appear close to the event horizon of a black hole. One of the pair falls into the black hole while the other escapes. In order to preserve total energy, the particle that fell into the black hole must have had a negative energy (with respect to an observer far away from the black hole). This causes the black hole to lose mass, and, to an outside observer, it would appear that the black hole has just emitted a particle. In another model, the process is a quantum tunnelling effect, whereby particle–antiparticle pairs will form from the vacuum, and one will tunnel outside the event horizon.[9]"

 

This helps me a little. 

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1 hour ago, RC94 said:

One amazing thing about this picture is that this black hole is in a galaxy that's 54 million light years from Earth.

Cosmically speaking though, that's like our backyard, right?

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2 hours ago, TheIronSheik said:

One thing I don't understand that they I've never really seem explained is how that radiation that is ejected out escapes.  A black hole is so strong, it even pulls in light.  Yet a jet of radiation is spewing out of it. How?

and where is all that 'stuff' going? is it endless? just being compressed further and further into the black hole? 

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Posted (edited)
7 minutes ago, El Floppo said:

and where is all that 'stuff' going? is it endless? just being compressed further and further into the black hole? 

One of the common-sense paradoxes about matter is that matter is almost entirely empty space -- even things we perceive as dense, heavy, and rock-solid. The capacity for matter to be compressed is all but infinite in the environment of a black hole.

Edited by Doug B
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2 minutes ago, Doug B said:

One of the common-sense paradoxes about matter is that matter is almost entirely empty space -- even things we perceive as dense, heavy, and rock-solid. The capacity for matter to be compressed is all but infinite in the environment of a black hole.

Thanks.

So the center of a black hole has matter approaching 100% density?...which would chicken/egg also make a huge gravitational field...

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8 minutes ago, El Floppo said:

Thanks.

So the center of a black hole has matter approaching 100% density?...which would chicken/egg also make a huge gravitational field...

You got it.

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From my understanding, it depends whether the matter was good or bad in its life.  If good, it'll see angelic humanoids and be spit out from a white hole towards a beautiful planet.  Heaven, I suppose.  If the matter is bad, it'll emerge into some fiery hell-scape. However,  if that matter also has an evil robot, it can hide out in it for awhile.  How long, I'm not sure....the science isn't there yet.

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6 hours ago, jamny said:
Quote

The sheer volume of data generated was also unprecedented – in one night the EHT generated enough data to fill half a tonne of hard drives.

:jawdrop:

I missed all the fun of this mornings announcement. 

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4 minutes ago, Galileo said:

:jawdrop:

I missed all the fun of this mornings announcement. 

They were rattling off some crazy stats at the press conference.

 

I mentioned earlier, How the Universe Works is doing a special episode on it tonight.

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3 hours ago, El Floppo said:

Thanks.

So the center of a black hole has matter approaching 100% density?...which would chicken/egg also make a huge gravitational field...

Usually described as infinite density rather than "100%".  Matter is essentially crushed to zero volume.  The concept is referred to as a gravitational singularity, and this is what is predicted by General Relativity.

 

 

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It is hard for me to comprehend how Einstein almost nailed this 100 years ago.  I can't get my arms around that part of this story.

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1 hour ago, Galileo said:

Stumbled across this just now for comparison... https://imgs.xkcd.com/comics/m87_black_hole_size_comparison.png

Disclaimer...I have not verified for accuracy.  I will need to crunch a few numbers when I get a chance.

Based on the reported mass of 6.5 billion solar masses, I calculate the Schwarzschild radius to be around 19 billion km (127 AU).  Pluto's orbit is in the neighborhood of 6 billion km (40 AU), so the radius of M87's event horizon is roughly 3x the radius of pluto's orbit.   Voyager 1 is about 21-22 billion km (~145 AU) away Thus the image appears to be a reasonable approximation. 

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3 hours ago, jamny said:

They were rattling off some crazy stats at the press conference.

 

I mentioned earlier, How the Universe Works is doing a special episode on it tonight.

About to start for those interested... 8 PM EST

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Very frustrated and disappointed thus far in How the Universe Works.  It was listed in my guide as a 2 hour show with a description related to the first image of a black hole.  I sat through the first hour, and it was interesting stuff, but mostly stuff I already knew and was familiar with.  There were a couple gems like the idea of a Planck Star that I had not heard before, which makes sense at some level...an interesting idea.  The second hour is now 15 minutes in.  It really isn't a continuation.  It is basically it's own show.  It has all been rehash of stuff that was covered in the first hour and still nothing yet on the new image or new information gleaned from the image.   :kicksrock:

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2 hours ago, Galileo said:

Based on the reported mass of 6.5 billion solar masses, I calculate the Schwarzschild radius to be around 19 billion km (127 AU).  Pluto's orbit is in the neighborhood of 6 billion km (40 AU), so the radius of M87's event horizon is roughly 3x the radius of pluto's orbit.   Voyager 1 is about 21-22 billion km (~145 AU) away Thus the image appears to be a reasonable approximation. 

Excellent Galileo. Thnx. I figured that you would have some interesting things to say about this. I was not wrong. 

Now, regarding the bolded - impressive! 

When you have some free time, I was hoping you could calculate the radius of my Schwantz - it's something I've been curious about for quite a while. 

👌

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15 minutes ago, Man of Constant Sorrow said:

Excellent Galileo. Thnx. I figured that you would have some interesting things to say about this. I was not wrong. 

Now, regarding the bolded - impressive! 

When you have some free time, I was hoping you could calculate the radius of my Schwantz - it's something I've been curious about for quite a while. 

👌

How long has it been since you've seen it?

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Posted (edited)
51 minutes ago, Galileo said:

Very frustrated and disappointed thus far in How the Universe Works.  It was listed in my guide as a 2 hour show with a description related to the first image of a black hole.  I sat through the first hour, and it was interesting stuff, but mostly stuff I already knew and was familiar with.  There were a couple gems like the idea of a Planck Star that I had not heard before, which makes sense at some level...an interesting idea.  The second hour is now 15 minutes in.  It really isn't a continuation.  It is basically it's own show.  It has all been rehash of stuff that was covered in the first hour and still nothing yet on the new image or new information gleaned from the image.   :kicksrock:

Meh...seems like the 10 PM show (NOT How the Universe Works) is going to be focused on getting the image.  False advertising on the 8-10 time slot.  

Edited by Galileo

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4 minutes ago, Galileo said:

Meh...seems like the 10 PM show (NOT How the Universe Works) is going to be focused on getting the image.  False advertising on the 8-10 time slot.  

They do that a lot. Combine a couple of shows and call it a new episode. Even gets the DVR to record it. They dont realize how it turns people off.

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7 minutes ago, Galileo said:

How long has it been since you've seen it?

OH - I see it daily - unfortunately, no one else sees it anymore...

...however, if I had an accurate radius - calculated & confirmed by a pro like you - well - ......

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This is like getting a picture of Bigfoot for real. Or a unicorn.

Damned amazing

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Posted (edited)

 

I borrowed the following from an email distribution list of a club I belong to:
 

Quote

 

A couple of years ago, there was an article in Discovery magazine, about a physicist having run a simulation on super computer to take the laws of nature to their limit and extrapolate how they would handle themselves just beyond the event's horizon of a black hole. Given that the gravity gradient is such that the fabric of space is stretched beyond what can be crossed by light, and that anything going at that speed would experience a completely halted flow of time (from our perspective), his conclusion was that, for whatever would be "inside" (or more appropriately "beyond") a black hole would look pretty much as the whole universe appears to us. Black holes, he proposed, would be creating entire universes, as large and complex as our own, along dimensions that are orthogonal to ours, with its own time flow, and forever locked away from observation and influence with our universe.

Looking the opposite way would suggest that our universe could simply be the 'inside' of a black hole in some other universe.

 

 

 

Edited by chet
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Israel landing on the moon later today ...live feed. Will be the fourth country to do so. Also challenging Chinese Rover to first lunar badminton tournament.

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I may get a timeout for this but I am attracted to Katie Bouman, the young lady that developed the algorithm to produce the image.

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Posted (edited)
22 hours ago, Man of Constant Sorrow said:

2) Depends on how much matter - even if constantly sucking. Hawking Radiation is always being emitted - thus, if too little matter, shrinkage will occur. 

I was in the pool!! I was in the pool!

Edited by matttyl

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After reading a bunch of articles about this yesterday, am I to understand that this isn't an ACTUAL photograph of a black hole?  This is an imaged black hole?  And if so, can someone explain that to me like I'm a 4 year old Albert Einstein?  

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11 hours ago, Galileo said:

Very frustrated and disappointed thus far in How the Universe Works.  It was listed in my guide as a 2 hour show with a description related to the first image of a black hole.  I sat through the first hour, and it was interesting stuff, but mostly stuff I already knew and was familiar with.  There were a couple gems like the idea of a Planck Star that I had not heard before, which makes sense at some level...an interesting idea.  The second hour is now 15 minutes in.  It really isn't a continuation.  It is basically it's own show.  It has all been rehash of stuff that was covered in the first hour and still nothing yet on the new image or new information gleaned from the image.   :kicksrock:

Well, we aren't all Galileos. 

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Posted (edited)
17 minutes ago, TheIronSheik said:

After reading a bunch of articles about this yesterday, am I to understand that this isn't an ACTUAL photograph of a black hole?  This is an imaged black hole?  And if so, can someone explain that to me like I'm a 4 year old Albert Einstein?  

As I think I understand it, yes.  This thing is so epicly far away, even with every telescope on Earth it's still just too small from our view to actually "see". 

But they can view it's radiation pattern, or something like that.  They took all that data, from the radiation (or similar) over time and used it to create the image.  It's also my understanding that they are "assigning" colors to it from that data. 

It was made doable by the algorithm created by Katie Bo;uman.  Not sure if totally accurate, but..."Seeing an orange on the moon would require a telescope lense the size of the Earth. Her algorithm lets you do it with many telescopes."

Edited by matttyl
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As an IT guy I think my favorite bit was that with 5 petabytes of data, it was faster to put the hard drives on a plane than to transfer it over the internet.

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16 minutes ago, That one guy said:

Are black holes spherical in nature?

Yes. Good read here from 2015 -- a lot of the then-contemporary thinking about black holes have gotten visual confirmation with the images released yesterday.

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27 minutes ago, heckmanm said:

As an IT guy I think my favorite bit was that with 5 petabytes of data, it was faster to put the hard drives on a plane than to transfer it over the internet.

~1k gigabytes is a terabyte.  ~1k terabyte is a petabyte?  Assuming 10 TB drives (and RAID), we're talking about.....~1,000 physical hard drives?

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Posted (edited)
16 minutes ago, matttyl said:

~1k gigabytes is a terabyte.  ~1k terabyte is a petabyte?  Assuming 10 TB drives (and RAID), we're talking about.....~1,000 physical hard drives?

Not sure about the drive size, but yeah, 5000 terabytes.

pic

Edited by heckmanm
fixed picture link

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