Holes A is a that has collapsed to extreme

Its is so high that not even can escape.

Why not?

In classical , the (vesc) is the speed an object needs to leave the gravitational pull of something.

Set KE = PE & solve for vesc. ...

At some distance, (RS) from a BH, the escape velocity is larger than the : vesc =c . Horizon

...Is a sphere around a black hole whose radius is RSch It is a “point of no return.” Once inside, nothing can escape since vesc > c. Presumably, all mass is at the center, a point called a “Singularity”

So you could cross the without even knowing it.

“Space is falling into the BH at the speed of light”

If a mass M is confined to a radius less then RSch it will become a black hole. Black Holes: Don’t Jump Into One!

If you fall into a Black Hole, you will have a big problem:

Your feet will be pulled with more gravity than your head.

You will be stretched out into “spaghetti”

………ouch!

Karl Schwarzschild* (1873-1916) used the new General to determine RS (while fighting WWI)

General Relativity (GR) is Einstein’s replacement for Newton’s theory of gravity.

GR is an extension of (SR), which starts with a basic assumption:

“The laws of physics are the same for all observers.”

* Who came up with U,V&W velocities. Also, the father of Martin Schwarzchild, (see Crosswell p. 40 & p.99 ) Special Relativity (Ch. 4, C&O, not required) Einstein’s assumption that observers moving at any speed (v) measure the same speed of light implies two effects* :

Implications of SR: -moving clocks run slow -simultaneity is relative -space & time are a one entity: “” -mass is a form of energy: E=mc2

(*both part of the “Lorentz Transformations”) Relativity Tested

If space is curved, then light from a star, passing near the , should be deflected.

But how could you see the star? ! A. Eddington observed a solar eclipse in 1919. ! were found in slightly different positions. ! This confirmed that the Sun’s mass can warp space! Newton Was Wrong

Special Relativity has been confirmed many times (by Kennedy & Thorndike, 1932, by Stillwell & Ives 1938, and your GPS!)

But GR was confirmed first, in 1919. GR describes gravity as the curvature of spacetime, not a force. X

or

Curvature of space = amount of mass/energy Black Holes & Relativity ! Black holes also distort space and time tremendously. ! In 2016, “gravity waves” from 2 colliding black holes were measured by the LIGO instruments in Hanford, WA & Livingston, LA