Nod to Drew Faust on her retirement at end of academic year
Brian is on board of overseers
April 1955, Albert Einstein on his death bed hospital bed at Princeton Hospital
Pad of paper w/ equations
Continuing to work quest for over 30 years on “unified theory” stitching together forces of nature into 1 explanatory equation
1 key question re: search to understand deep fundamental forces of nature
How did the universe begin?
We have theories
Big Bang
We can take mathematics and wind the universe in reverse to a fraction of a second after beginning
To go further back in time (to true time 0), the math breaks down
Can we find a math formula to even explain conditions at time 0 or earlier?
These questions go back to at least Isaac Newton
During black death, he retreated to his family’s country home, did a huge amount of work on theory, observation, math, etc.
Universal law of gravity came from this period
Gravitational force defined by how big objects are and their distance from each other
His math mostly works for celestial objects “breathtaking” predictive power
He also found something “embarassing” his math could describe the force of gravity but couldn’t say how gravity actually works! What is the mechanism?
I leave the question to the reader
Albert Einstein wants to figure out how gravity actually works
10 long years on this
The rubber sheet analogy w/ the bowling ball causing deformations and other balls movement being affected by the deformation
He gave us both the analogy and the actual equations to describe
Observational data, over time, proved that Einstein’s equations were confirmed his theory of general relativity
Gravitational ripples in fabric of space created by two dense objects rotating around one another in space
Harder to test/observe than other dynamic systems
Several decades of work
Einstein never thought the gravitational waves would ever be detected
Kip Thorne and others posited an experiment
Sept 14 2015 2 different gravity wave detectors (LIGO’s) independently confirmed gravitational ripples generated by collision of 2 black holes 1.3 billion light years away (1.3 billion years ago)
LIGO Hanford
LIGO Livingston
This experiment first turned on 2 light days in advance of the wave actually hitting earth
Quantum Mechanics
Theories first emerged during Einstein’s lifetime. He didn’t really like it
Particle-wave duality
Quantum tunneling
On sub-atomic layer, electrons DO occasionally pass thru impermeable walls
Problem there’s a feature of Quantum Mechanics that conflicts w/ General Theory of Relativity
Uncertainty Principle we cannot, with precision, predict with certainty both the position and velocity of an object at the same time
Uncertainty reigns in the microscopic world
This uncertainty also applies to the fabric of space-time and, therefore, disrupts Relativity
Einstein’s geometry works at macroscopic layer but not at the frothy_uncertain_undulating conditions at the smallest scale of reality
Intro to String Theory
Note that String Theory does not yet have experimental verification of its theory the way that relativity and QM have enjoyed
Question — what is the smallest constituent element of reality?
Greeks defined It as atom
But we know that atoms can be split into
Electrons, protons, neutrons
Some of those particles can be broken up into even smaller elements like quarks
String Theory hypothesizes that smallest element of nature is a string or loop or filament that oscillates or vibrates and the different types of vibration are what creates different kinds of sub-atomic particles
Mid 1980’s when mathematics behind string theory first emerged
The math also suggested a unification of QM and relativity
But String Theory also suggests that the universe may also contain additional dimensions beyond the traditional 3
Question — standard model has a bunch of standard number re: mass and other characteristics (size ,charge, etc.) of various particples in the atomic zoo
But why these numbers?
Even small differences in these numbers could create huge changes in nature of universe
20 numbers each describe different ways that the strings can vibrate
Strings also vibrate in the curled up additional dimensions
If we knew exactly what the extra dimensions look like, we could finish the vibration calculations of the string and, thus, be able to derive the WHY of each standard model number
Hints of a multiverse where other universes are built on different standard model numbers?
The theoretical work continues. Many questions unanswered but worth pursuing