DOC PREVIEW
CU-Boulder ASTR 1020 - Lecture Notes

This preview shows page 1 out of 3 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 3 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 3 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

1ASTR 1020: Stars & GalaxiesMarch 7, 2008• MasteringAstronomy Homework on Star Death is due Mar. 10th.• Reading: Chapter 19, sections 19.1-19.2.• Exam 2 next Friday, March 14th. (Chapters 15.3 – 19.2).Today: Dr. Einstein’s Universe• Einstein comes to America in 1933.• The General Theory of Relativity (and Gravity).• Black holes & worm holes.• Einstein: The man and the politician.1879-1955Einstein in America• A phenomenon.• Physicist as Rock Star!Einstein at Lincoln University in 1946At Hopi House, Grand Canyon in 1931Spacetime• Special relativity showed that space and time are not absolute• Instead they are inextricably linked in a four-dimensional combination called spacetimeRubber Sheet Analogy• Matter distorts spacetime in a manner analogous to how heavy weights distort a rubber sheetInsert TCP 5e Figure S3.2Key Ideas of General Relativity• Gravity arises from distortions of spacetime• Time runs slowly in gravitational fields• Black holes can exist in spacetime• The universe may have no boundaries and no center but may still have finite volume• Rapid changes in the motion of large masses can cause gravitational waves2• Great circle is shortest distance between two points• Parallel lines eventually converge• Angles of a triangle sum to > 180°• Circumference of circle is < 2πrWhat is curved spacetime?What is gravity?Rubber Sheet Analogy• Mass of Sun curves spacetime– Free-falling objects near Sun follow curved paths– Circles near Sun have circumference < 2πrClicker Question: According to general relativity the presence of matter curves spacetime. That means a planet in our solar systema) Feels a force of gravity coming from the sunb) Moves as if there was a force coming from the sunc) Experiences “free fall” or free movement by moving in a curved orbitd) None of the abovee) b and cClicker Question: According to general relativity the presence of matter curves spacetime. That means a planet in our solar systema) Feels a force of gravity coming from the sunb) Moves as if there was a force coming from the sunc) Experiences “free fall” or free movement by moving in a curved orbitd) None of the abovee) b and cCurvature near Black Hole• Continued shrinkage of Sun would eventually make curvature so great that it would be like a bottomless pit in spacetime: a black hole3Shortcut Through Spacetime• Some mathematical solutions of the equations of general relativity allow for shortcuts called wormholes that are tunnels through hyperspaceAre Wormholes Really Possible?• Wormholes are not explicitly prohibited by known laws of physics but there is no known way to make one• If wormholes exist, then they can be used for time travel• Time travel leads to paradoxes that some scientists believe should rule out the possibility of wormholesEinstein: The man & husbandEinstein’s Rules for Milevain 1914:• Serve meals in my room.• Renounce all personal relations. Don’t expect any intimacy from me.• You will stop talking to me if I request it.• You will not belittle me in front of the children.Albert & Mileva1905Einstein & The Bomb•E=mc2 is the basis behind the nuclear bomb.• Einstein wrote to President Roosevelt in 1939 that an atomic weapon was possible.with Leo Szilard


View Full Document
Download Lecture Notes
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Lecture Notes and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Lecture Notes 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?