Black Holes - Would Earth be sucked in?

[Tortorella's Rant]

The real question is, if the moon was made of barbeque spare ribs, would you eat it?

I know I would! Heck, I'd have seconds! Then polish it off with a tall cool budweiser.

[Neufy161]

Is that because the Sun doesn't have the mass to become a black-hole or because the gravitational pull wouldn't be any stronger than it is now, or something else?

[Neufy161]

That's not correct. If you compressed the sun (via some means) to become a black hole, the earth's orbit would not change.

<- astrophysics degree

[GodzillaDeuce]

That's not correct. If you compressed the sun (via some means) to become a black hole, the earth's orbit would not change.

<- astrophysics degree

[Sharpshooter]

its because the gravitational force would remain the exact same,

If the sun became a black hole, its mass would be identical to what it is now, the earths mass, obviously, would remain unchanged, and the distance between the two objects would remain unchanged... trajectories of components in our solar system would remain unchanged.

[silverpig]

Yes. This is correct. There is no difference between orbiting a star a some standard planetary distance and orbiting a black hole of the same mass at the same distance. The difference comes in when you get really close due to relativistic space-time warping effects. I would have to run the numbers (probably couldn't do it anymore as I haven't been in physics for a while now), but the orbit of a planet just outside the sun's surface (so, really close) might actually be significantly different if the sun turned into a black hole.

Basically, the orbits are exactly the same if they are infinitely far from the central mass, they are completely different at extremely short distances, and the differences become significant near the star (so multiples of the star's radius).

For distances of the earth's orbit, we wouldn't ever notice, but a very sensitive experiment may be able to tell.

[Buddhas Hand]

That's not correct. If you compressed the sun (via some means) to become a black hole, the earth's orbit would not change.

<- astrophysics degree

[babych]

I did not know that. I haven't done physics in a while, and most of what I'm saying is what I heard on TV. I could just be remembering it wrong, so don't quote me on any of this.

I am pretty sure black holes have greater gravitational force than the sun it originated from, but as to why that is true, I couldn't say since I don't remember it. I do remember that ball on the bed analogy, and that made the most sense to me. It goes further to say if you kept compressing the ball, the "depression" would continue to increase, but the increase closer to the ball is greater than increase further from it (I'm not sure about the italicized part). It essentially becomes like an upside down pylon.

Edit: I love the Soundgarden reference, but I don't think it would be called a "sun" anymore.

Edit 2: You are all using Newton's formula for gravity. Remember, Newton is taught to give you the fundamentals, but a lot of what he believed was wrong. You can destroy matter (E=mc²). I think atomic weapons work by destroying a small amount of mass to create a significant amount of energy

[Red Light Racicot]

I figured this would be useful:

F=Gm1m2 divided by R squared

F is the force between the masses

G is the gravitational constant

m1 is the first mass

m2 is the second mass

R is the distance between the centers of the masses

Basically density makes no difference

[silverpig]

Babych: you have it backwards. The atom weighs more than the sum of the individual protons and neutrons.

[Hugemanskost]

Babych: you have it backwards. The atom weighs more than the sum of the individual protons and neutrons.

[silverpig]

You have to take the mass of electrons into account, too, when calculating atomic mass.

[Neufy161]

so if you compressed the sun into a black hole, would you only witness extreme gravitational forces inside the radius of the current sun, but forces outside the current surface would remain completely unchanged?

[babych]

Babych: you have it backwards. The atom weighs more than the sum of the individual protons and neutrons.

[Hugemanskost]

Sorry silverpig but I am totally correct. The nucleus of an atom weighs LESS than the sum of its' protons and neutrons. This "missing mass" is the energy stored to keep the nucleus together and is released when the nucleus is fissioned.

http://library.think...ing_energy.html

As to the electrons - they weigh about 1/2000 of what a proton or neutron weigh and so don't really factor into this.

It has to be this way otherwise there wouldn't be so much energy involved in fission. Energy gets stored in the nucleus to keep it together and balances the equation as mass (E-mc^2).

If it were the other way then it would cost more energy to fission than we would get from the process.

[babych]

True this. It's called mass defect if I remember correctly.

[Ghostsof1915]

It seemed so much more realistic when it first came out.

[Buddhas Hand]

NASA's Swift Satellite Discovers a New Black Hole in our Galaxy

10.05.12

An X-ray outburst caught by NASA's Swift on Sept. 16, 2012, resulted from a flood of gas plunging toward a previously unknown black hole. Gas flowing from a sun-like star collects into a disk around the black hole. Normally, this gas would steadily spiral inward. But in this system, named Swift J1745-26, the gas collects for decades before suddenly surging inward. Credit: NASA's Goddard Space Flight Center

› Download video in high resolution from Goddard's Scientific Visualization Studio

NASA's Swift satellite recently detected a rising tide of high-energy X-rays from a source toward the center of our Milky Way galaxy. The outburst, produced by a rare X-ray nova, announced the presence of a previously unknown stellar-mass black hole.

"Bright X-ray novae are so rare that they're essentially once-a-mission events and this is the first one Swift has seen," said Neil Gehrels, the mission's principal investigator, at NASA's Goddard Space Flight Center in Greenbelt, Md. "This is really something we've been waiting for."

An X-ray nova is a short-lived X-ray source that appears suddenly, reaches its emission peak in a few days and then fades out over a period of months. The outburst arises when a torrent of stored gas suddenly rushes toward one of the most compact objects known, either a neutron star or a black hole.

The rapidly brightening source triggered Swift's Burst Alert Telescope twice on the morning of Sept. 16, and once again the next day.

Named Swift J1745-26 after the coordinates of its sky position, the nova is located a few degrees from the center of our galaxy toward the constellation Sagittarius. While astronomers do not know its precise distance, they think the object resides about 20,000 to 30,000 light-years away in the galaxy's inner region.

Ground-based observatories detected infrared and radio emissions, but thick clouds of obscuring dust have prevented astronomers from catching Swift J1745-26 in visible light.

The nova peaked in hard X-rays -- energies above 10,000 electron volts, or several thousand times that of visible light -- on Sept. 18, when it reached an intensity equivalent to that of the famous Crab Nebula, a supernova remnant that serves as a calibration target for high-energy observatories and is considered one of the brightest sources beyond the solar system at these energies.

Even as it dimmed at higher energies, the nova brightened in the lower-energy, or softer, emissions detected by Swift's X-ray Telescope, a behavior typical of X-ray novae. By Wednesday, Swift J1745-26 was 30 times brighter in soft X-rays than when it was discovered and it continued to brighten.

"The pattern we're seeing is observed in X-ray novae where the central object is a black hole. Once the X-rays fade away, we hope to measure its mass and confirm its black hole status," said Boris Sbarufatti, an astrophysicist at Brera Observatory in Milan, Italy, who currently is working with other Swift team members at Penn State in University Park, Pa.

The black hole must be a member of a low-mass X-ray binary (LMXB) system, which includes a normal, sun-like star. A stream of gas flows from the normal star and enters into a storage disk around the black hole. In most LMXBs, the gas in the disk spirals inward, heats up as it heads toward the black hole, and produces a steady stream of X-rays.

But under certain conditions, stable flow within the disk depends on the rate of matter flowing into it from the companion star. At certain rates, the disk fails to maintain a steady internal flow and instead flips between two dramatically different conditions -- a cooler, less ionized state where gas simply collects in the outer portion of the disk like water behind a dam, and a hotter, more ionized state that sends a tidal wave of gas surging toward the center.

"Each outburst clears out the inner disk, and with little or no matter falling toward the black hole, the system ceases to be a bright source of X-rays," said John Cannizzo, a Goddard astrophysicist. "Decades later, after enough gas has accumulated in the outer disk, it switches again to its hot state and sends a deluge of gas toward the black hole, resulting in a new X-ray outburst."

This phenomenon, called the thermal-viscous limit cycle, helps astronomers explain transient outbursts across a wide range of systems, from protoplanetary disks around young stars, to dwarf novae -- where the central object is a white dwarf star -- and even bright emission from supermassive black holes in the hearts of distant galaxies.

Swift, launched in November 2004, is managed by Goddard Space Flight Center. It is operated in collaboration with Penn State, the Los Alamos National Laboratory in New Mexico and Orbital Sciences Corp. in Dulles, Va., with international collaborators in the United Kingdom and Italy and including contributions from Germany and Japan

[Drybone]

There is no such thing as gravity

[Buddhas Hand]