I heard you liked Iridium

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Mikey_R

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Jul 29, 2019
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my teacher of physics would bitch slap you to death, after seeing you referring to pressure when talking about density.

When you are forcing materials into a tighter space than it would naturally be in, ie. increasing a materials density without changing anything, you are going to generate alot of heat and pressure due forces caused by the atoms being closer together.
 

Loufmier

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Jul 29, 2019
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When you are forcing materials into a tighter space than it would naturally be in, ie. increasing a materials density without changing anything, you are going to generate alot of heat and pressure due forces caused by the atoms being closer together.
its not what i was talking about. thing that bugged me was units of measurement.
 

Mikey_R

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kg/m^2 is the right units for density. The units for pressure is N/m^2, or a force divided by the area.
 

Loufmier

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kg/m^2 is the right units for density. The units for pressure is N/m^2, or a force divided by the area.
density is a mass/volume. it`s a firs time i see people measuring volume in m^2. 1 N is equal to 202g 102g, so pressure can be expressed as kg/m^2
 
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Mikey_R

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To be fair, I missed that as well (as well as making the same mistake, doing physics early morning isn't good), however, pressure cannot be expressed in units of kg/m^2, the units just don't add up.

Newtons is a force and in SI units a newton is equal to kgm/s^2

So, putting the units in, pressure = kgm/[s^2][m^2], or, kg/[s^2]m, which isn't the same as kg/[m^3] (or, for that matter, kg/[m^2]).

Also, I have no idea where you got N = 202g from, just saying.
 

Whovian

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Jul 29, 2019
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I was about to come in and say that mass and force are totally different units, but it looks like you've got it covered, Mikey_R. :)

Ah, alright, thanks for clearing that up. I really ought to do more research on this type of thing. Or perhaps pay more attention in physics. I now understand. A bit more, at least, off to look up the bits that I don't.

*mumbles something about iridium*

:p

The black hole thing's a lot different than the media suggests it to be. Assuming a perfectly spherical planet, the gravitational force on an object not in the planet is G*m*M/r^2, where G is a constant, M is the mass of the planet, m is the mass of the object, and r is the distance between the object and the centre of the planet. (This is technically a certain limit of General Relativity, which seems to be more "correct," but I won't go into that.)

So, if the Earth shrunk to the size of a black hole without changing mass and remaining spherical, the gravitational force on the Moon would remain constant; there wouldn't be any gravitational effects. Someone who was standing on the surface wouldn't have any ground underneath them, but otherwise, the gravitational force remains constant.

Now here's the clincher. For small objects (say, a black hole,) you can get closer to the centre before having to enter the object. And, as r gets small, G*m*M/r^2 grows ... pretty freakin' huge.

So it's not a problem of density, but rather of distance. ;)
 

Bluehorazon

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density is a mass/volume. it`s a firs time i see people measuring volume in m^2. 1 N is equal to 202g 102g, so pressure can be expressed as kg/m^2

It was just a derp. It is meant to be cubic not square. And still it is neither pressure nor density. But if you look at the context and not so much the number 2 it is very clear that is supposed to be a 3. And well high density simply creates pressure inside the object. Its like a japanese subway, the more you put in a defined space the harder it gets to compress it further.

The black hole thing's a lot different than the media suggests it to be. Assuming a perfectly spherical planet, the gravitational force on an object not in the planet is G*m*M/r^2, where G is a constant, M is the mass of the planet, m is the mass of the object, and r is the distance between the object and the centre of the planet. (This is technically a certain limit of General Relativity, which seems to be more "correct," but I won't go into that.)

So, if the Earth shrunk to the size of a black hole without changing mass and remaining spherical, the gravitational force on the Moon would remain constant; there wouldn't be any gravitational effects. Someone who was standing on the surface wouldn't have any ground underneath them, but otherwise, the gravitational force remains constant.

Now here's the clincher. For small objects (say, a black hole,) you can get closer to the centre before having to enter the object. And, as r gets small, G*m*M/r^2 grows ... pretty freakin' huge.

So it's not a problem of density, but rather of distance. ;)

Well if you want to explain blackholes and the "Schwartzschild-radius" very easily you could make up a simple explanation. If an object shrinks so much that its theoretical event-horizon would lie outside of its real material form we would see it as a blackhole. If we would simply increase the mass of the earth without making it larger we would reach a point at which the light cant escape the surface of the earth and others would see it as a blackhole. In theory every object could be viewed as a blackhole with its eventhorizon inside the object, not outside.

The only real difference between a normal object and a blackhole is the potential to grow. If the earth would turn into a blockhole by getting incredible compressed it would allow the so created blackhole to absorb matter. The earth cant do this, because everything that is on the surface of our planet can leave it. As soon as something enters the eventhorizon it cant leave anymore. But since this area would be really small for the earth it wouldnt even be a stable blackhole since it would lose mass faster than it could gain it. Even our sun does not necessarily has enough mass to create a stable blackhole.

Also whenever people calculate the gravitational force between two objects in school they actually assume that they are both blackholes or even more objects with no size at all. So if the earth would shrink into a blackhole the gravitational force on the moon would indeed change. Because right now parts of the earth are farther away and some are nearer (which would make no difference if the earth would be a perfect globe, which it isnt). But the impression that replacing the earth with a blackhole of the same size would suck in our whole star-system is definitly wrong.
 

Roady

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Jul 29, 2019
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If you read the article you're citing, you'll note that the element's discoverer, Humphry Davy, originally named the element Aluminum.

Except if you read the article you'll find he named it Alumium, not AlumiNum

The only real difference between a normal object and a blackhole is the potential to grow.
This is wrong (or at least to the best of my knowledge, black holes are funky sometimes), actually neither has more or less potential for growth. Potential for growth has more to do with how much crap happens to be nearby.
(Ignoring of course, that most large enough objects will collapse into a black hole once gravitational forces become larger than outward pressures)
(also a black hole can lose mass by sending out Hawking radiation, though for larger holes this is offset by radiation falling into it)

Realistically if the earth were replace by a black hole of the same mass and momentum, it would just chug along and nothing significant would change to the solar system around it. The moon would continue to spin, and everything would stay moving as they were. (ok, so the moon would stop feeling tidal forces and not accelerate away anymore, but not much more)
Black holes aren't magical sucking things. they're just heavy, and have gravity. And because of the inverse square law in gravity you get a small region within nothing may escape. And the difference with normal matter is... you hit the normal matter and get repulsed by it before getting so close.
 

SonOfABirch

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Jul 29, 2019
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What everyone needs to remember is that black hole theory is hugely theoretical. New hypothesis are coming to light recently that are contradictory to the generally accepted theory, yet are still very plauible. The problem is that we cannot test these theories, so they will remain as hypothesis for the considerable future.
 

Roady

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What everyone needs to remember is that black hole theory is hugely theoretical. New hypothesis are coming to light recently that are contradictory to the generally accepted theory, yet are still very plauible. The problem is that we cannot test these theories, so they will remain as hypothesis for the considerable future.

True to some extent, though there are quite a bit of characteristics that we have been able to verify trough observation or simulation and comparison, though others are more like extrapolations based on what we know of how physics works.
Most of the contradictory statements however seem to be about how the buggers actually came to be, especially some of the bigger ones. Which in cases can be bigger than should have been possible given some formation theories.
 
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Whovian

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What everyone needs to remember is that black hole theory is hugely theoretical. New hypothesis are coming to light recently that are contradictory to the generally accepted theory, yet are still very plauible. The problem is that we cannot test these theories, so they will remain as hypothesis for the considerable future.

I believe Black Holes have been confirmed to [likely, but isn't everything?] exist. \Checks

Yep.
 

Riuga

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Jul 29, 2019
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Now Greg needs to add titanium tetroxide (i think it was called that?) collectors.

Because Titanium.

And a rock processor. 1 titanium ingot from 64 cobble (alright this is a bit OP). 1 iridium ingot from 400 stacks of cobble.