"In Black Holes BLACK HOLES "In the beginning, there was light.' That is true in the case of black holes too. Black holes are the result of burned out stars that have collapsed on themselves. When a star begins to run out of fuel, the internal pressure of the fusion reactions, which was before, counteracted by gravity, begins to win over gravity. The star soon can no longer support its own weight and its outer layers escape its gravitational pull. This powerful explosion is called a super nova.
The star then passes through a period of evolution, which is characterized by its mass. If the mass of the burned out core, which was left behind by the supernova, is less then 1. 5 times the mass of our sun (sun = 1 solar mass), the remaining object is expected to become a white dwarf. If the mass is between 1. 5 and 3 solar masses, then the remaining object is expected to turn into a neutron star. Both of these stars are extremely massive.
If the period at the end of this sentence were composed of a neutron star's core then it would weigh as much as 4 fully loaded super-tankers. However, if the remaining core is greater than about 3 solar masses, it will collapse in upon itself and become a super massive singularity. The power of the collapse is so intense that the core can be reduced from about 10, 000 km to about 10 km in a fraction of a second. These singularities are so massive that light itself cannot escape its gravitational pull. This is called a black hole. According to theories and advanced mathematics, the black hole's core continues falling inward on itself getting progressively smaller and smaller.
Eventually the black hole's core shrinks down to the size of an elementary particle and supposedly even smaller. But how massive and how small are black holes? This depends on two key things. One the mass and two a proportional radius. This in turn states that density has a great part in the formation of gravity. One very simple equation used to show escape velocity for a spherical body of mass is shown below. The proportion is 0.
00000036577 – The sun's mass is equal to about (1. 99 E^30) kg. – The radius of the sun is about (696, 000) km – Therefore the escape velocity of the sun is about 6. 19 km / s Similarly, as noted above, if we increase the mass of the sun by a factor of 3 and decrease the radius of the mass (collapsed core remnant from a supernova) to about 8. 893 km then the escape velocity reaches approximately 3. 0 E^8 which is the speed of light.
– Sun's mass times 3 is approximately (5. 974 E^30) kg. – Approximate radius of supernova's core remnant (8. 893) km – Escape velocity equals (2. 99792458 E^08) m / s Now our sun will never experience this because for this to occur the sun would need to triple its mass. And since the sun is constantly losing mass, due to the tremendous amounts of energy being released, this won't occur.
Also, the radius required, for even the entire suns current mass, to become a black hole would be approximately (2. 964 km). From the information above you can conclude that mass isn't the only variable that plays a role in the formation of a black hole. Density has much to do with the event. If our sun were to lose its internal gas pressure and gravity were to compress its mass to a sphere with radius 8. 8-km, thus greatly increasing the density, then it would become a black hole.
Using the equation above, we can derive an equation that will determine the radius of a spherical object with mass required for that object to become a black hole. – P = proportion of original escape velocity proportion above – M = mass of object – C = speed of light Just as a realization as to how dense objects must be to become a black hole, here is a chart with various objects and their required size (spherical) to become a black hole. Object Radius (m) Radius Similar Size Of Mercury 4. 91 E-04 Thickness of cardboard Venus 7. 15 E-03 Thickness of yarn Earth 8. 90 E-03 Thickness of a pencil Mars 9.
56 E-04 Thickness of a staple Jupiter 2. 83 Height of a ceiling Saturn 8. 47 E-01 About 1 yard Uranus 1. 29 E-01 Height of a CD case Neptune 1. 52 E-01 Width of a check Pluto 1. 92 E-05 Thickness of paper Sun 2.
96 E+03 32 football fields Now once the black hole has been born, what happens to the immense gravitational fields around it? Once an object enters the eternal void, what happens? To understand this we must know how gravity works. Think of gravity as a flat flexible grid. As you place things on it (matter) they imprint on the grid causing a small dip depending on the weight (mass) of the object. If you were to roll a spherical object past it, the rolling object would curve due to the small imprint of the stationary object. This represents what matter does to space-time. When a spaceship passes a planet, it doesn't curve towards the planet, the planet just redefines the definition of a straight line.
While outside of the gravitational field the planet spaceship goes "straight'. But when the spaceship enters the gravitational field, its "straight' travel is then redefined to "curve' around the planet. Black holes work on this principal also. The tremendous mass of the black hole almost causes a literal "hole ' in the space-time. If you were to travel in a spiral orbit around the black hole progressively headed towards the black hole you would eventually enter the event horizon.
The event horizon is the "point of no return'. Once something has entered the event horizon there is no apparent return. It gets "sucked' into the gravitational hole and "never' returns. What happens as it approaches and once it enters? If a spaceship were to head towards the event horizon two major events would occur. 1) There would be a dramatic red phase shift by light and, consequently all electromagnetic pulses, trying to escape from the black hole's gravitational pull.
2) Time would become extremely distorted too. First, assuming we have an observatory in a stable orbit around the black hole with extra sensitive sensors on board, the station would notice that all light would shift towards the red side of the color spectrum. This is due to the photons using up some of their energy trying to escape the black hole's grasp. Since the photons lose energy so does the light wave.
And the less energy the light wave has, the lower the frequency. This red shift would continue to get more and more shifted until the light waves would be so low that they would become radio waves and eventually undetectable. This is not a Doppler shift due to movement. This is a phase shift due to the curvature of space-time.
Keep in mind that the light waves, or electromagnetic waves, don't slow down, they merely lose energy. They still travel at the speed of light. Secondly, time is effected. If there were a gigantic perfectly sequenced clock mounted on the rear of the ship facing the observatory, the people on the observatory would notice that the clock would be slowing down. This is suggested by Einstein's theory of relativity. The clock continues to slow and slow, until it eventually stops (relative to the observers).
It would be as if the ship never entered the black hole. However, from the ship's point of view everything would appear fine until it neared the event horizon. Upon nearing the event horizon the ship would be severely distorted and heated. Any human or machine would instantly be ripped apart by the gravitational gradient.
The gravitational gradient is caused by the tremendous difference in the acceleration of gravity from point A to point B. Using the Law of Universal Gravitation we can find the difference of force between a persons head and feet (assuming they enter feet first). — Let the distance from the black hole = 30 km (distance to the event horizon) — Assume the mass of the black hole is 10 solar masses — Assume that the mass of the person is 90. 8 kg (200 lb.
) — Assume the height of the person = 2 m (6′ 6. 7″ ; feet are at event horizon) — Universal Gravitation constant = 6. 673 E^-11 (NT-m.