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Gravitational waves felt from black-hole merger 3 billion light-years away

KurtFehl

Member
Thanks for the explanation. So forward time travel is possible but not backward i.e it was BS in movies :p

Both of these makes sense and I did knew about the ISS space station example. So if these guys in space are near a strong gravity mass, which will obviously pull them inside, but if they can somehow avoid it, they will experience time slower than the outside world.

If you haven't seen Interstellar you really should. Kinda does the time travel thing very well. It's a really good movie.
 

Extollere

Sucks at poetry
Just to put this into perspective, 3 billion light years away is far, far outside of our own galaxy. It's even further away than the nearest galaxy, Andromeda! Crazy to think we'd be able to detect something like this so far away flying through empty space or in another galaxy all together.
 

MrOogieBoogie

BioShock Infinite is like playing some homeless guy's vivid imagination
49 suns lmao

It's like equating console power to GameCubes taped together.
 

dabig2

Member
To be clear, we should note that this limit of 20 solar masses is before the collapse. In the process a lot of mass is lost, and this is how you get a final BH with only about 3 solar masses.

True. That got me thinking, when Andromeda and Milky Way merge in a few billion years, will the supermassive black holes in the middle of each one also merge to produce these gravitational waves? And how much mass will they likely be at the instant they do merge. Like the Milky Way's black hole is over 4 million solar masses right now and I imagine Andromeda's is much larger.
 

KurtFehl

Member
I have seen Interstellar and yeh, it is a really good movie. Although it sucks in the last third act of the movie and the ending was crap.

I tend to agree with you but it had scientific accuracies in there so that's why I recommended it. Especially the time travel stuff.

Wasn't a fan of the their act tho but overall, really good.
 

Frillen

Member
iOwuoD7.jpg

I'm about to start watching this show, please tell me you didn't spoil anything.
 
True. That got me thinking, when Andromeda and Milky Way merge in a few billion years, will the supermassive black holes in the middle of each one also merge to produce these gravitational waves? And how much mass will they likely be at the instant they do merge. Like the Milky Way's black hole is over 4 million solar masses right now and I imagine Andromeda's is much larger.

Yes. I looked it up, and apparently Andromeda's black hole is about 10 times more massive than the Milky Way's. In the merger, some of the mass will be radiated away in the gravitational waves, such that the final BH will have less than the sum of the masses of two initial BHs. Simulations calculate that a couple million solar masses will be lost in this way.
 

ag-my001

Member
They and a similar European group named Virgo are collectively the 1,300 authors of a report on the most recent event that will be published in the journal Physical Review Letters on Thursday.

Any other scientists wondering how the order past author #5 was decided? If not alphabetical, how could they decide who really contributed the 1157th most?
 
If you fell in, and could look back into the universe, you would see the universe race ahead forward in time and then you would die soon after as tidal forces rip you apart. The person falling in doesn't feel millions of years, they have 'normal' time, its just that space is warped to the point that the rest of the universe will race ahead.
Holy shit...

Basically our time doesn't apply to black holes, is that it?


its just that space is warped to the point that the rest of the universe will race ahead.
This is so weird and fascinating.
 
Holy shit...

Basically our time doesn't apply to black holes, is that it?


This is so weird and fascinating.

It's not really a special property of black holes. Even on Earth, the time for someone on top of a mountain runs faster than for someone on the ground. GPS has to be calibrated to compensate for this. It's just that in the BH case these effects can be very strong.
 
It's not really a special property of black holes. Even on Earth, the time for someone on top of a mountain runs faster than for someone on the ground. GPS has to be calibrated to compensate for this. It's just that in the BH case these effects can be very strong.
I didn't know about this. But why?



I need to learn more about this.
 
I didn't know about this. But why?



I need to learn more about this.

I mean, to really get into the why you must study General Relativity. To give you the gist of it, the key point is that the gravitational field is really the geometry of space time. If you wish to calculate the distance between two points on flat space, with coordinates (x1,y1,z1) and (x2,y2,z2), you would use the pythagorean formula:

l^2= (x1-x2)^2+(y1-y2)^2+(z1-z2)^2.

In space time, a kind of distance, called the interval, may be defined similarly, but now you include also the time between the two events. In this case, if the times are t1 and t2, then the interval is

s^2= -(t1-t2)^2 +(x1-x2)^2+(y1-y2)^2+(z1-z2)^2

Note the crucial minus sign in front of the time term. This is the main difference between time and space.

Up to now, this is for flat space. Whenever you have you mass or energy, it deforms space time and changes the formula above, very roughly, by multiplying (you should really integrate) the (x1-x2)^2 and (t1-t2)^2 factors, etc by functions of space and time, which together form what is called a metric tensor.

For the gravitational field of the Earth, or of a Black Hole, the time difference squared is multiplied by (1-2 U(r)/c^2), where U(r) is the gravitational potential at the height r you are calculating and c is the speed of light.
 

BADMAN

Member
Fixed that for you.

Is there any chance like a huge comet or a planet or something collides with the earth with little to no warning? That is legit one of my biggest fears.

Gamma Ray Bursts. You're thinking Gamma Ray Bursts. We could theoretically get smacked by a gamma ray burst from the collision of two stars merging into a black hole, which would be an instant and inevitable death that no one would see coming. Probably won't happen though.
 
I mean, to really get into the why you must study General Relativity. To give you the gist of it, the key point is that the gravitational field is really the geometry of space time. If you wish to calculate the distance between two points on flat space, with coordinates (x1,y1,z1) and (x2,y2,z2), you would use the pythagorean formula:

l^2= (x1-x2)^2+(y1-y2)^2+(z1-z2)^2.

In space time, a kind of distance, called the interval, may be defined similarly, but now you include also the time between the two events. In this case, if the times are t1 and t2, then the interval is

s^2= -(t1-t2)^2 +(x1-x2)^2+(y1-y2)^2+(z1-z2)^2
I understand/knew all of this for sure.

Note the crucial minus sign in front of the time term. This is the main difference between time and space.
I don't remember really why the minus (physics is not my major but I had some classes because engineering)

Up to now, this is for flat space. Whenever you have you mass or energy, it deforms space time and changes the formula above, very roughly, by multiplying (you should really integrate) the (x1-x2)^2 and (t1-t2)^2 factors, etc by functions of space and time, which together form what is called a metric tensor.

For the gravitational field of the Earth, or of a Black Hole, the time difference squared is multiplied by (1-2 U(r)/c^2), where U(r) is the gravitational potential at the height r you are calculating and c is the speed of light.
Now this is where you lost me. Metric sensor is not an unknown name to me but the rest, I have no clue ahah

But thanks for the explanation. I shall dig deeper into this when I have the time.
 
Would this be similar to hawking radiation where 1 solar mass worth of information disappeared from the universe as a form of gravitational waves?
 
I understand/knew all of this for sure.

I don't remember really why the minus (physics is not my major but I had some classes because engineering)
Well the minus sign doesn't really matter for this, but it has to do with the difference between changes in velocity (which affect time) and rotations in space (which don't).

Now this is where you lost me. Metric sensor is not an unknown name to me but the rest, I have no clue ahah

But thanks for the explanation. I shall dig deeper into this when I have the time.

You're welcome :)

Would this be similar to hawking radiation where 1 solar mass worth of information disappeared from the universe as a form of gravitational waves?

Information is conserved. Gravitational waves are not really any different from electromagnetic waves from a radio in this sense.
 
Thanks for the explanation. So forward time travel is possible but not backward i.e it was BS in movies :p

Both of these makes sense and I did knew about the ISS space station example. So if these guys in space are near a strong gravity mass, which will obviously pull them inside, but if they can somehow avoid it, they will experience time slower than the outside world.

Afaik, they wont experience it any different than before. Time for them only slows down relative to a different state of spacetime. There is no general standard spacetime, you could argue for humans it is the state on the surface of the earth and anything else is not normal for us but that is only a thought construct. You look at them and they seem to slow down, but they look at you and they see you accellerating, you both look at your watch and it ticks away as usual, nothing different. I might remember this wrong but that is kinda how the twin paradox could be interpreted.
 
Afaik, they wont experience it any different than before. Time for them only slows down relative to a different state of spacetime. There is no general standard spacetime, you could argue for humans it is the state on the surface of the earth and anything else is not normal for us but that is only a thought construct. You look at them and they seem to slow down, but they look at you and they see you accellerating, you both look at your watch and it ticks away as usual, nothing different. I might remember this wrong but that is kinda how the twin paradox could be interpreted.
Yes, I understand it. This is also why I loved Interstellar since the beginning dealt with exactly this subject. Hopefully we get another movie with similar scientific accuracy sometime in the future.
 

Randomizer

Member
I'm about to start watching this show, please tell me you didn't spoil anything.
No, unless I missed something? The show is mainly about the characters anyway not particularly about explaining anything. Similar to Lost in that regard and no surprise it's from the same guy. The Leftovers is much better than Lost though.
 
Are there theories about what it is exactly that's making up the wave aside from just "space-time?" Or I guess is there any good reading on this that I could somewhat understand as someone with a basic grasp of mechanics and electromagnetism?
 
Are there theories about what it is exactly that's making up the wave aside from just "space-time?" Or I guess is there any good reading on this that I could somewhat understand as someone with a basic grasp of mechanics and electromagnetism?
It is just space-time in the same way that an electromagnetic wave is just as oscillation of the electromagnetic field. There's nothing underneath, so to speak.

If you want a more technical explanation, the oscillating field is called the metric tensor. It is a 10 component field that tells you how to measure distances in curved spacetime.
 
In the latest LIGO event, a black hole 19 times the mass of the sun and another black hole 31 times the sun’s mass, married to make a single hole of 49 solar masses.

hey I pulled out my calculator and added this up and it should be 50 solar masses. nice try scientists
 
I love astronomy and anything to do with space so all this talk fascinates me. What I would give to see all these cosmic things up close with my own eyes. Stars, nebulae, the planets, the galaxies, etc.

That math equation that someone posted hurts my head though.
 

Rentahamster

Rodent Whores
Correct.

However, is it not theoretically possible to survive much longer passing the horizon should the black hole be considerably larger? My understanding is that smaller black holes are actually incredibly more dangerous when approaching their singularities because there's less time approaching theirs as compared to those in supermassive black holes.

Could a person not survive being torn to shreds, then, if the black hole was massive enough to make the transition from the horizon to the singularity predictably smooth?

Edit: I also wrote "event horizon" earlier. LOL

Yeah, with a massive enough black hole. That's the concept behind the gentle singularity in the movie Interstellar.
 

Mohonky

Member
49 times the mass of the sun? Seems kind of small given our Sun is a dot compared to some of the shit out there.
 

Mohonky

Member
Afaik, they wont experience it any different than before. Time for them only slows down relative to a different state of spacetime. There is no general standard spacetime, you could argue for humans it is the state on the surface of the earth and anything else is not normal for us but that is only a thought construct. You look at them and they seem to slow down, but they look at you and they see you accellerating, you both look at your watch and it ticks away as usual, nothing different. I might remember this wrong but that is kinda how the twin paradox could be interpreted.

Basically someone watching you enter a black hole would appear to almost be not moving at all.

Theorhetically as you enter the horizon you could look back and see them moving faster, but light is being bent so greatly you could actually be able to see shit like the back of your head and your lower half would seem to extend forever....at least until you kond of get crushed into oblivion.
 

Xe4

Banned
So coooool. This is the third time we've detected gravitational waves. The science going into detecting them is super cool as well. It's just a simple Michelson Interferometer, yet it has to detect variations in space that are smaller than an atom.

ok good much thanks i will sleep well tonight

nevermind

To be entirely fair, the chance of an extinction level asteroid hitting the Earth (unless we can move it) is very high. The chance of it happening in the next 10,000-100,000 years, however, is very low.

This event released more energy than all the stars in the observable universe, so it's definitely over 9000 at least.
And these are stellar mass black holes. The energy released by two supermassive black holes merging would dwarf this by many, many orders of magnitude. It's crazy how the real world is far more insane than most fiction.
 
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