# Creating a black holes?

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I watched a video that said that theoretically you could make Earth a black hole by adding Mass until it collapsed into a black hole.

So? If you can add Mass thru acceleration how fast would something have to move before it collapsed into a black hole? I'm assuming it would be a proportional type process? Would there be a constant velocity that would apply?

Assuming it is theoretically possible?

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Its not about adding mass to earth, its about crunching the current earth mass into a smaller space. Adding mass would not cause a black hole, squezing earth into about 8.7mm radius would.

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2 hours ago, koti said:

Its not about adding mass to earth, its about crunching the current earth mass into a smaller space. Adding mass would not cause a black hole, squezing earth into about 8.7mm radius would.

I'll revisit the video maybe I misunderstood. I was sure it said adding enough pressure by adding Mass would cause the collapse. It even gave a formula. I watched it again and got the same impression.

I don't know how to link it.  It's on YouTube called (The Black hole Tipping Point) posted by minutephysics.

Is it because I am confusing matter with Mass?

Edited by jajrussel
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35 minutes ago, jajrussel said:

I'll revisit the video maybe I misunderstood. I was sure it said adding enough pressure by adding Mass would cause the collapse. It even gave a formula. I watched it again and got the same impression.

I don't know how to link it.  It's on YouTube called (The Black hole Tipping Point) posted by minutephysics.

Is it because I am confusing matter with Mass?

Compressing mass into higher pressure so it takes less space doesn't require adding mass. No matter how much mass you add without crunching it into smaller space, you will not end up with a black hole. You need to squeeze mass into a ridiculously small space to end up with a black hole, the formula they mention in your youtube film is most likely the Schwarzschild radius formula.
I'm not sure how you could confuse mass with matter, you need to ask a specific question here.
To give you an idea how dense matter has to be for a black hole to form - if you'd take a matchbox full of Neutron Star matter which is much less dense than that of a black hole, the matchbox would weigh ~3 billion tonnes.

Edited by koti
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32 minutes ago, koti said:

Compressing mass into higher pressure so it takes less space doesn't require adding mass. No matter how much mass you add without crunching it into smaller space, you will not end up with a black hole. You need to squeeze mass into a ridiculously small space to end up with a black hole, the formula they mention in your youtube film is most likely the Schwarzschild radius formula.
I'm not sure how you could confuse mass with matter, you need to ask a specific question here.
To give you an idea how dense matter has to be for a black hole to form - if you'd take a matchbox full of Neutron Star matter which is much less dense than that of a black hole, the matchbox would weigh ~3 billion tonnes.

Your reply indicates that there is a distinction between Matter and Mass that I wasn't making.

I am going to try and insert a link to the video.

It appears to have worked. They said Matter I may have confused it with Mass? Apparently, I did.

But this seems to have led to another question. If there is a distinction, between Matter and Mass. Again I'm having trouble remembering does an object get bigger or smaller as it nears c?  I thought it was bigger?

you apparently have posted another reply while I'm writing so I'll pause to read it. Maybe it will clear up the next question regarding the object size and it's velocity?

Edited by jajrussel
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1 hour ago, jajrussel said:

I'll revisit the video maybe I misunderstood. I was sure it said adding enough pressure by adding Mass would cause the collapse. It even gave a formula. I watched it again and got the same impression.

I don't know how to link it.  It's on YouTube called (The Black hole Tipping Point) posted by minutephysics.

Is it because I am confusing matter with Mass?

Can't help with the Black Hole though, sorry.

Edit: Ha,ha. Just seen your new post. Well done.

Edited by Tub
Too late!
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11 minutes ago, Tub said:

Can't help with the Black Hole though, sorry.

Edit: Ha,ha. Just seen your new post. Well done.

Thank you!

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Just now, jajrussel said:

Thank you!

You're welcome.

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27 minutes ago, jajrussel said:

Your reply indicates that there is a distinction between Matter and Mass that I wasn't making.

I am going to try and insert a link to the video.

It appears to have worked. They said Matter I may have confused it with Mass? Apparently, I did.

But this seems to have led to another question. If there is a distinction, between Matter and Mass. Again I'm having trouble remembering does an object get bigger or smaller as it nears c?  I thought it was bigger?

I you apparently have posted another reply while I'm writing so I'll pause to read it. Maybe it will clear up the next question regarding the object size and it's velocity?

I browsed through the video, they are confusing with that statement in the video where they say that just adding matter together can create a black hole. The important part to keep in mind is that matter needs to reach the Swarzchild radius to become a black hole - matter needs to be squeezed to the point that it reaches a critical density and that point is the Swarzchild radius. Matter and mass are very different physical concepts. Matter is the atoms that form molecules which form stuff around us. Mass is one of the „qualities” of matter. Mass is like weight but its independand of gravity where „weight” depends on gravity. If you have an object of say 1kg of mass on earth it will weigh less on the moon and more on Saturn because the gravity dictates how much it weighs. On all 3 planets the mass is the same though - 1kg. If that 1kg object flies around in space where there is no gravity it it still has a MASS of 1kg but weighs nothing. I don’t know if this helps, Im trying

I suggest we stay away from what happens with an object at near light speeds for now, you need to understand the basics first or you’ll get confused beyond comprehension when trying to understand General Relativity.

Edited by koti
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7 minutes ago, koti said:

I browsed through the video, they are confusing with that statement in the video where they say that just adding matter together can create a black hole. The important part to keep in mind is that matter needs to reach the Swarzchild radius to become a black hole - matter needs to be squeezed to the point that it reaches a critical density and that point is the Swarzchild radius. Matter and mass are very different physical concepts. Matter is the atoms that form molecules which form stuff around us. Mass is one of the „qualities” of matter. Mass is like weight but its independand of gravity where „weight” depends on gravity. If you have an object of say 1kg of mass on earth it will weigh less on the moon and more on Saturn because the gravity dictates how much it weighs. On all 3 planets the mass is the same though - 1kg. If that 1kg objects flies around in space where there is no gravity prsebt it still has a MASS of 1kg. I don’t know if this helps, In trying

Thanks, I do seem to have the ability to be as confusing as I am confused. Maybe I am expecting the wrong thing to happen when increasing an objects velocity. It also probably matters in how I am applying it in my thought. In my thought the Earth gets bigger and bigger thru velocity until it eventually reaches the point of collapse. In my mind it would be a different velocity for a particle. I could be wrong for thinking this. Not just because the entire thought is wrong, but because I'm thinking the particle density is lower and it would have to go really really fast before it collapsed into a black hole.

Anyway thanks :).

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1 hour ago, koti said:

I browsed through the video, they are confusing with that statement in the video where they say that just adding matter together can create a black hole. The important part to keep in mind is that matter needs to reach the Swarzchild radius to become a black hole - matter needs to be squeezed to the point that it reaches a critical density and that point is the Swarzchild radius. Matter and mass are very different physical concepts. Matter is the atoms that form molecules which form stuff around us. Mass is one of the „qualities” of matter. Mass is like weight but its independand of gravity where „weight” depends on gravity. If you have an object of say 1kg of mass on earth it will weigh less on the moon and more on Saturn because the gravity dictates how much it weighs. On all 3 planets the mass is the same though - 1kg. If that 1kg object flies around in space where there is no gravity it it still has a MASS of 1kg but weighs nothing. I don’t know if this helps, Im trying

I suggest we stay away from what happens with an object at near light speeds for now, you need to understand the basics first or you’ll get confused beyond comprehension when trying to understand General Relativity.

Thanks from me too, Koti. At my level of scientific nescience, i did find it helpful - especially about the difference between mass and matter/weight. I gather, then, that mass is independent of acceleration and motion in general too? If i could employ a little analogy: if i had a bullet in my hand and  tossed it gently at a wall, it would just bounce back harmlessly; if i threw it as hard as i could, it may mark the wall but would still bounce back; but if i shot it from a gun, it would do significant damage to the wall. So the mass of the bullet always stays the same but its weight increases exponentially with accelerating velocities. Forgive me if i ignore your suggestion about NLS, ( just for one moment, haha, ), but i imagine that if the bullet did hit the wall at NLS then the wall would be totally destroyed.

Edited by Tub
clarification
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1 hour ago, Tub said:

Thanks from me too, Koti. At my level of scientific nescience, i did find it helpful - especially about the difference between mass and matter/weight. I gather, then, that mass is independent of acceleration and motion in general too? If i could employ a little analogy: if i had a bullet in my hand and  tossed it gently at a wall, it would just bounce back harmlessly; if i threw it as hard as i could, it may mark the wall but would still bounce back; but if i shot it from a gun, it would do significant damage to the wall. So the mass of the bullet always stays the same but its weight increases exponentially with accelerating velocities. Forgive me if i ignore your suggestion about NLS, ( just for one moment, haha, ), but i imagine that if the bullet did hit the wall at NLS then the wall would be totally destroyed.

Your bullet analogy is accurate. In fact, mass and energy are equivalent as Einstein’s famous E=mc^2 equation tells us. Say you would like a certain force of the bullet to act on a wall, you can choose between increasing the mass of the bullet or increasing its velocity - both will have exactly the same effect on the wall, from the wall view point the damage will be the same. What happens when a bullet reaches relativistic velocities is not really interesting from the wall view point...obviously the wall will receive a lot more energy if the bullet hits it at a higher velocity so it will receive more damage.

What is really interesting is that a bullet traveling at a near light speed will change its mass (not weight) it will  also experience length contraction (it will change its size) and time will flow slower for the fast bullet than for an observer which is stationary relative to the bullet.

Edited by koti
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There is a distinction between the kind of mass you add.

Adding relativistic mass, that is mass due to relative motion, will not cause gravitational collapse.
This mass is a frame dependent effect,  i.e. not present in it own , or rest, frame.

Adding inertial mass ( or matter )  to the Earth does have an effect.
The Earth is not like a star, it has no radiation pressure to counteract gravity.
Once a certain mass is reached, electron degeneracy will stop collapse. As more mass is added, neutron degeneracy is the last holdout.
but once you reach the point of several solar masses, gravitational collapse to a BH is unavoidable.
( mass increases with the cube of the radius while gravity decreases with the square )

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17 minutes ago, MigL said:

There is a distinction between the kind of mass you add.

Adding relativistic mass, that is mass due to relative motion, will not cause gravitational collapse.
This mass is a frame dependent effect,  i.e. not present in it own , or rest, frame.

Adding inertial mass ( or matter )  to the Earth does have an effect.
The Earth is not like a star, it has no radiation pressure to counteract gravity.
Once a certain mass is reached, electron degeneracy will stop collapse. As more mass is added, neutron degeneracy is the last holdout.
but once you reach the point of several solar masses, gravitational collapse to a BH is unavoidable.
( mass increases with the cube of the radius while gravity decreases with the square )

Thanks for pointing out the distinction between relativistic and inertial mass, I forgot to mention this as I was trying to keep relativity out until jajrusell felt comfortable with the basics of mass/matter/energy/gravity.
jajrussel & tub - the above post by MigL is very well put, listen to what he's saying and if something is unclear don't hesitate to ask.
MigL loves to spend Saturdays on explaining BH physics and relativity to people on the internet

Edited by koti
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15 minutes ago, MigL said:

There is a distinction between the kind of mass you add.

Adding relativistic mass, that is mass due to relative motion, will not cause gravitational collapse.
This mass is a frame dependent effect,  i.e. not present in it own , or rest, frame.

Adding inertial mass ( or matter )  to the Earth does have an effect.
The Earth is not like a star, it has no radiation pressure to counteract gravity.
Once a certain mass is reached, electron degeneracy will stop collapse. As more mass is added, neutron degeneracy is the last holdout.
but once you reach the point of several solar masses, gravitational collapse to a BH is unavoidable.
( mass increases with the cube of the radius while gravity decreases with the square )

☺☺☺ All right an answer I can understand, thank you, thank you, thank you. So long as no one asks me to explain it, I'm good! I probably could, but I would likely just confuse the issue even more.☺☺☺

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Not the whole day !

This is my weekend off of work, just got up about an hour ago, having a leisurely 2nd coffee and checking messages.

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2 hours ago, MigL said:

Adding relativistic mass, that is mass due to relative motion, will not cause gravitational collapse.
This mass is a frame dependent effect,  i.e. not present in it own , or rest, frame.

One way of realising this must be true is to remember that the relativistic mass is a relative effect. In other words, someone else (moving relative to you)will see your mass increase. But you won't see your mass increase (because you are never moving relative to yourself). It is impossible for you (Earth) to become a black hole from their point of view and not yours. Therefore it can't be correct.

This is why a lot of people avoid the concept of relativistic mass, because it can mislead in this way. (And it isn't really necessary; it is just a way of talking about energy.)

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2 hours ago, MigL said:

Not the whole day !

This is my weekend off of work, just got up about an hour ago, having a leisurely 2nd coffee and checking messages.

It was just my attempt at a joke but please don’t mind it as someone recently commented that my sarcasm could be sold to governments as a weapon of mass destruction.

7 minutes ago, Strange said:

One way of realising this must be true is to remember that the relativistic mass is a relative effect. In other words, someone else (moving relative to you)will see your mass increase. But you won't see your mass increase (because you are never moving relative to yourself). It is impossible for you (Earth) to become a black hole from their point of view and not yours. Therefore it can't be correct.

This is why a lot of people avoid the concept of relativistic mass, because it can mislead in this way. (And it isn't really necessary; it is just a way of talking about energy.)

#jajrussel -  Inertial mass, matter and energy are all the same thing. Sounds weird but its very true.

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2 hours ago, MigL said:

There is a distinction between the kind of mass you add.

Adding relativistic mass, that is mass due to relative motion, will not cause gravitational collapse.
This mass is a frame dependent effect,  i.e. not present in it own , or rest, frame.

Adding inertial mass ( or matter )  to the Earth does have an effect.
The Earth is not like a star, it has no radiation pressure to counteract gravity.
Once a certain mass is reached, electron degeneracy will stop collapse. As more mass is added, neutron degeneracy is the last holdout.
but once you reach the point of several solar masses, gravitational collapse to a BH is unavoidable.
( mass increases with the cube of the radius while gravity decreases with the square )

Even if you were to prevent collapse somehow and maintain a constant density, adding mass will still eventually lead to a black hole.  Keep in mind that the event horizon radius is directly proportional to the mass of the BH.  But the mass of an object with a constant density increases by the cube of radius.  So for example, the Schwarzschild radius for one the mass of the Earth is 8.87e-3 meters.  If we were to add mass to the Earth which doubled it radius, but kept the density the same, then we will have increased the mass and the Schwarzschild radius  by a factor of 8 (to 0.07 meters)

Increasing the radius by a factor of 100 (making the radius of the Earth 637,800,000 meters, increases the Schwarzschild radius to 8870 meters

A factor of 1000 gives a radius of 6378,000,000 m and a Schwarzschild radius of 8,870,000 m

A 10,000 fold increase in radius to 63,780,000,000 puts the Schwarzschild radius at 8,870,000,000 m

and a 50,000 fold increase gives a 3.189e11 m radius for the solid body of the Earth, and a 1.1e12 m Schwarzschild  radius, which means that the surface of the Earth is now inside the event horizon.    Of course, by this time, we are well into the super massive BH range in terms of mass.  And, as you pointed out, the density would not remain constant, meaning that the mass would grow even faster compared to the radius.

But this does point out a interesting fact, that the Schwarzschild density of a black hole decreases with increased mass.

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12 hours ago, jajrussel said:

I watched a video that said that theoretically you could make Earth a black hole by adding Mass until it collapsed into a black hole.

So? If you can add Mass thru acceleration how fast would something have to move before it collapsed into a black hole? I'm assuming it would be a proportional type process? Would there be a constant velocity that would apply?

Assuming it is theoretically possible?

Great question and the crux of it is solved by the following.....

4 hours ago, MigL said:

There is a distinction between the kind of mass you add.

Adding relativistic mass, that is mass due to relative motion, will not cause gravitational collapse.
This mass is a frame dependent effect,  i.e. not present in it own , or rest, frame.

And let me add it is quite refreshing seeing a member asking a genuine question, without any pre-conceived "absolute" agenda derived answer.

To add to the already many correct answers you have been given, if we were to squeeze the present mass of the earth into around a couple of centimeters it would become a BH, likewise if we could magically squeeze the mass of the Sun into a diameter of approximately 5kms, it to would become a BH.

Interesting to note though, that if the Sun were magically turned into a BH, by squeezing its mass into a 5km diameter, all the planets would continue to orbit along their present paths. In other words, as is sometimes mistakenly thought, a BH is not an all-purpose vacuum cleaner. In such an unlikely scenario, only comets and asteroids that ventured within limits based on its mass and speed would get sucked in. The absolute "point of no return" is around 1.5 Schwarzchild radius, based on "c"

Much more knowledge on BHs in relatively laymans speak, can be gained from http://casa.colorado.edu/~ajsh/

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