PHIL 160: Lecture 2. Science news… Some background on the Tevatron and the (never-built) Superconducting Super Collider
Welcome to Fermilab!
Our mission is to discover what the universe is made of and how it works.
We're asking three simple, challenging questions here at the frontier of particle physics:What is the nature of the universe?What are matter, energy, space and time?How did we get here and where are we going?
Fermilab Director Michael S. Witherell
Was the world’s highest-energy particle collider
4 miles in circumference and housed in a tunnel 30 feet below the ring
Accelerators send particles racing around the Tevatron at 99.9999% of the speed of light
Send two kinds of subatomic particles, protons and antiprotons, around the ring in opposite directions.
At two points, beams of these particles flow right into each other.
Causing millions and millions of collisions, at the rate of almost two million each second.
Many kinds of devices record details of the debris to identify, based on theory, what kinds of particle are being produced in the collisions.
Using the Tevatron, Fermilab scientists have confirmed:
The bottom quark (1977)
The top quark (1995)
The tau neutrino (2000)
“We collide particles in the hope of seeing something never seen before.”
But predicted by theory!
The CDF Collider Detector.
Each detector has about one million individual pathways for recording electronic data generated by the particle collisions. The signals are carried over nearly a thousand miles of wires and cables--each one connected by hand and tested individually.
Books? No, they are complex
Words? No, they are also complex
Letters? No, can be broken down into just 0 and 1…
If it makes no sense to take apart the 0 and the 1, we’ve found the “atomic” components of the library
The universe as the library
What are its most basic elements?
The forces of nature are the grammar, spelling, and algorithm
The subatomic particles, quarks and leptons, are currently believed to be the “atomic” (un-cut-able) elements of the universeThe “library of matter”
What basic assumptions can we identify that underlie and motivate research in particle physics?
That the entities and laws studied by particle physicists are what make up and govern all other entities and processes and regularities.
A commitment to simplicity (just a few particles and a few laws): nature is (ultimately simple – i.e., elegant)
That “invisible” (not able to be directly observed) objects are respectable – and, indeed, necessary for (some) theories of physics.
What warrants these assumptions?
entities posited by science:
“My evidence for atoms and quarks is as good as the evidence [the TV provides that the Pope exists].
“What is that evidence? Tracks of particles in a bubble chamber. In the Fermilab accelerator, the “debris” from a collision between a proton and an antiproton is captured by a 3 story, 60 million dollar detector. …
“Here, the “evidence” – the “seeing” – is tens of thousands of sensors that develop an electrical impulse when a particle passes…”
“All of these impulses are fed by through hundreds of thousands of wires to electronic data processors.
“Ultimately, a record is made on spools of magnetic tape, encoded by zeroes and ones.
“Science, especially particle physics, gains confidence in its conclusions by duplication” and by frequent tests of the experimental apparatus.
The late great Stephen Jay Gould
Harvard paleontologist and evolutionary theorist
One of the strongest defenders of Darwin and evolutionary theory
One of the strongest critics of some aspects of evolutionary theory.