During the late 1800’s, the field of science desperately needed a new theory to revise the old Newtonian-based physics. The laws of Newtonian principles were beginning to show problems; for example, the precession of Mercury’s orbit could not be completely accounted for. Einstein revolutionized all aspects of science and modern thought through his theories of general and special relativity and idea of equivalence. Albert Einstein was taken seriously after rigorous testing of his theories. One example is the famous advance of Mercury's perihelion. Because Newton's law did not correctly predict this, Einstein's theory gained approval for a new revolution in science. Furthermore, the eclipse experiment of 1919 helped to prove his bending of light theory. These proofs helped him to gain wider acceptance of his theories. Einstein recieved the a Nobel Prize in 1921, not for his research on relativity, but for his 1905 work on the photoelectric effect.

Time’s “Man of the Century” for 1900s Helped defrock Newton’s Laws as absolute –See also quantum physics Changed our entire concept of space and time Key figure in the nuclear age

March 14, 1879: Albert Einstein was born in Ulm, Germany

Einstein saw a wonder when he was four or five years old: a magnetic compass. The needle's northward swing, guided by an invisible force, impressed him. The compass convinced him that there had to be "something behind things, something deeply hidden."

Einstein knew, from then on, that he wanted to teach math and Science at a University someday. The problem was, he wasn’t a very good test-taker and could not get a job at a University because of it. Rumor has it that he had even failed a Math test, but some people question that because of the way grades were assigned back then.

Albert Einstein develops his Special Theory of Relativity. He did this while working as a Patent Clerk in Germany. He wasn’t really even a scientist at the time.

Relative to who is watching, space and time are transformed near the speed of light: distances appear to stretch; and clocks tick more slowly. Einstein’s theory meant that Sir Isaac Newton was wrong. Space and time are not absolute - and the universe we live in is not actually the one Newton "discovered.”

Einstein His work anchors the most shocking idea in twentieth century science: we live in a universe built out of tiny bits of energy and matter. Next, in April and May, Einstein publishes two papers. In one he invents a new method of counting and determining the size of the atoms or molecules in a given space. In the other he explains the phenomenon of Brownian motion. The net result is a proof that atoms actually exist - still an issue at that time.

And then, in June, Einstein completes special relativity - which adds a twist to the story: And of course, Einstein isn't finished. Later in 1905 comes the most famous relationship in physics… The energy content of a body is equal to the mass of the body times the speed of light squared. At first, even Einstein does not understand the full implications of his formula.

In 1907, Einstein begins to apply the laws of gravity to his Special Theory of Relativity. In 1910, Einstein answered a basic question: "Why is the sky blue?" He solved the problem by looking at the effect of the scattering of light by individual molecules in the atmosphere. In 1911, he finally gets a job as a Professor of Physics at the German University. In 1913, Einstein begins work on his new Theory of Gravity.

Einstein completes his General Theory of Relativity. Einstein challenged the way the world thought about gravity – and Sir Isaac Newton himself - by describing gravity as the warping of space- time, not a force acting at a distance.

A solar eclipse proves Einstein right, and he becomes an overnight celebrity. An experiment had confirmed that light rays from the sun were deflected by the gravity of the sun in just the amount Einstein had predicted in his theory of gravity, General Relativity.

During the 1920's Edwin Hubble and Milton Humason photographed the spectra of many galaxies with the 100 inch telescope at Mount Wilson.

Comparison of laboratory to blue-shifted object Comparison of laboratory to red-shifted object

Hubble and recession of galaxies: Further away,Greater redshift ! Hubble guessed their distances by size and brightness -underestimated by factor 10!

Like raisins in rising raisin cake, galaxies move away from each other in our expanding universe.

Wavelength is shorter when approaching Stationary waves Wavelength is longer when receding

Cepheid variable stars are pulsating stars, named after the brightest member of the class, Delta Cephei. Cepheids are brightest when they are hottest, close to the minimum size. Since all Cepheids are about the same temperature, the size of a Cepheid determines its luminosity. Thus there is a period-brightness relationship for Cepheids. Since it is easy to measure the period of a variable star and they can be very bright, Cepheids are wonderful for determining distances to galaxies!

“Instability strip” -- region in H-R diagram with large, bright stars Outer regions of star are unstable and tend to pulsate Outer regions of star are unstable and tend to pulsate Star expands and contracts, getting brighter and fainter

Henrietta Leavitt studied variable stars that were all at the same distance (in the LMC or SMC) and found that their pulsation periods were related to their brightnesses Polaris (The North Star) is not constant, it is a Cepheid variable!

Cepheid Variable Stars as distance indicators: “standard candle” Vital discovery by Henrietta Leavitt (1912)

Andromeda found to be far outside Milky Way – another “island universe” : galaxy! Edwin Hubble in 1924 identified Cepheids in Andromeda (M33)  showed they were far outside of Milky Way! His first big discovery. Next was expansion of the universe – wow! Hubble using new 100” Hooker telescope at Mt. Wilson (above LA)

Using the Doppler effect, Hubble calculated the velocity at which each galaxy is receding from us. Using the period and brightness of Cepheid variables in distant galaxies, Hubble estimated to distances to each of the galaxies.

Hubble noticed that there was a linear relationship between the recessional velocity and the distance to the galaxies.Hubble noticed that there was a linear relationship between the recessional velocity and the distance to the galaxies. This relationship is know as Hubble’s Law:This relationship is know as Hubble’s Law: v = H o d recessional velocity = Hubble’s Constant  Distance

H o is known as the Hubble constant and is about 75km/s/Mpc. This means that a galaxy that is 1 megaparsec from Earth will be moving away from us at a speed of 75km/s.

v = H o * d Ho is called the Hubble constant. It is generally believed to be around 65 km/sec/Mpc…plus or minus about 10 km/sec/Mpc. Note: The further away you are, the faster you are moving!

To get a rough idea of how far away a very distant object is from Earth, all we need to know is the object's velocity. The velocity is relatively easy for us to measure using the Doppler effect, or Doppler shift. Distance = Velocity/(Hubble constant)

v = H o d = cz where v = velocity from spectral line measurements d = distance to object H o = Hubble constant in km s -1 Mpc -1 z is the redshift Space between the galaxies expands while galaxies stay the same size

v = H 0 d and d =vt Solving for t, we find the age of the Universe is: t ~ 1/H 0 t ~ 1/H 0 If H 0 = 65 km/s/Mpc, then the age of the Universe is ~ 16 x 10 9 yr or 16 billion years

The greatest mistake of Einstein’s career might not have been such a mistake after all. A new growing movement states the Universe might not end in a Big Crunch, but rather, the force of antigravity is now being used to explain why the expansion of the universe is not slowing down. And now this repulsive force is instantly becoming the biggest mystery in science.

Einstein begins pursuing his idea of a unifying theory that ties everything in the universe together. Einstein continued in his dying days, to figure out a single central theory that explained everything in the universe. An extension of his work has become known as String Theory, which says that everything in the universe is made up of tiny strings of energy – nothing, really!

1933: Einstein and his wife, Elsa, escape Nazi Germany and set sail for the United States. 1939: World War II begins. Einstein writes a now famous letter to President Franklin D. Roosevelt urging nuclear research and warning him of Germany’s building of an atomic bomb

This is a picture of his last blackboard.

"Put your hand on a hot stove for a minute, and it seems like an hour. Sit with a pretty girl for an hour, and it seems like a minute. THAT'S relativity." "Anyone who has never made a mistake has never tried anything new." "If A equals success, then the formula is: A=X+Y+Z. X is work. Y is play. Z is keep your mouth shut."

1.The Laws of Physics are the same for all observers, no matter their motion, as long as they are not accelerated. (Galilean inertia, essentially) 2.The speed of light is constant and is the same for all observers independent of their motion relative to the light source.

Galilean Relativity at low relative speeds

Showed Newton didn’t know everything. –Together with quantum physics, threw a wrench into determinism Forever changed the way we think about space and time. –Moving watches don’t stay synchronized –Gravity not really a force but curvature No action at a distance after all? Nuclear energy/weapons

The Special Theory of Relativity (1905) Einstein elevated the Michelson-Morley null result into a fundamental principle of nature: Albert Einstein ( ) This required him to treat “space” and “time” as a single entity: The speed of light is constant, independent of the motion of the source or the observer. SpaceTime Spacetime

The General Theory of Relativity (1916) Extension of special relativity to include gravity. Matter warps spacetime; falling object follow straight lines in curved, 4- dimensional spacetime. “Space tells matter how to move; matter tells space how to curve.”

General Relativity and the Universe Einstein attempted to find solutions to his equations that described the complete spacetime “shape” of the universe. Much to his consternation, he discovered that he could not find static solutions – they all described a universe that was either expanding or contracting. Since this was clearly nonsense, Einstein modified his equations, adding a term that corresponded to the energy of the vacuum. He called this term the cosmological constant.