Tomorrow marks the last lecture of my course, PHY1308 (“Introductory Physics – Electricity and Magnetism”). The topic of the last lecture – topics, really – were chosen by the students of my class. This class is intended for pre-med students, and while not all of them are planning to go to medical school each student is extremely bright and all of them have excelled in various ways in my class. We have struggled, together at times, to come to a better understanding of the natural world through physics.
The title of my last lecture for 2010 is “Beyond Einstein: How Light Led the Way to a Dark Cosmos.” The topics included will be physics in 1890, the early life of Albert Einstein, 1905 and the papers that started twin revolutions (I will demonstrate the photoelectric effect using household items), and the implications of those twin revolutions for our current understanding of the universe.
What lies behind this lecture are an innumerable set of experiments conducted over the past two hundred years. The 1800s were a revolutionary period for our understanding of electricity and magnetism, themselves two faces of a single electromagnetic force described by Maxwell’s Equations. Each symbol in Maxwell’s Equations was determined not just through logic but through the sweaty and often dangerous labor of experimentalists. Combining prowess in the laboratory with a profound grasp of mathematics, men like Faraday, Coulomb, Biot and Savart pieced together the laws of nature that governed electric and magnetic phenomena. It was Maxwell who extended that work and formed what now call “Maxwell’s Equations.” There, in turn, predicted the existence of electromagnetic waves that traveled without the aid of a medium and did so at the speed of light. Again, the labor and toil of men such as Hertz revealed the existence of such waves, and confirmed that light is such a wave.
I say all of this, because experimental results – asking Nature questions and having the will and the skill to tease answers from her – are ALWAYS behind our most profound understanding of Nature. This understanding does not end with mechanics, thermodynamics, and electromagnetism; experimental work was CRITICAL to making sense of the quantum theory of radiation and matter, as well as the theory of relativity. Without experiment, such ideas would not have been formed; without experiment, such ideas could not have been tested, or even fully honed into their present state. The light of experiment has even led us to understand how little matter and light play a role in the shape and destiny of our cosmos; these most profound issues seem to be ruled by as-yet-unidentified dark matter and dark energy. It will be the twin lights of experimental physics and a deep understanding of mathematics that will again illuminate even these dark corners of our cosmos.
So tonight, as Jodi and I sat in a coffee shop in Allen, she working on her final exam and I working on my last lecture, my ears pricked up when the big bang became a topic of discussion amongst a group of grade-school girls sitting at a table behind us. One of them proudly proclaimed intellectual defiance when her teacher came to teach about the age of the universe and the big bang. “I asked her why I should believe all of that,” the girl said to her friends, “and the teacher basically told me that it was because a bunch of scientists say so. Well, I say that the big bang theory is just that – a theory – and we shouldn’t take it so seriously.”
And I cringed. Because that’s what scientists do when confronted with a person so defiant. She is young, and that was factored into my response. But I also recall that I was once very devout, and yet somehow the fact that the universe was born billions of years ago and evolves according to a set of well-defined laws did not challenge my faith. It added a new dimension to my view of the universe, and I came to understand that it was not idle philosophy or mere speculation that proclaimed such things; it was the weight of observation, the voice of Nature herself speaking in the ear of the experimentalist and the ear of the theorist that gave rise to these understandings.
This girl behind us continued on, talking about how she told her teacher that she would simply be absent from class when the teacher taught about the big bang. She then went on to say how she evangelized her friends in gym class and told them all to go to church.
Why am I saying all of this? My lecture tomorrow will recount what we understand now, from experimental measurement, about the age and fate of the universe. There is no time in 50 minutes to understand all the “whys” – really, just the “whats.” But behind every word – every “what” – is a string of experiments that have pointed the way, and a mathematical framework that makes predictions and allows for tests. In other words: science. Perhaps this girl was unfairly summarizing her teacher’s response when explaining why her teacher said she should believe in the big bang. Perhaps this girl could never be swayed by facts because her mind is not open to the possibility of Nature behaving in a way other than she would like. Who can say?
I can only really say this: be humble before Nature. She has a lot to teach us, if only we are willing to listen. Shutting Nature out of our lives endangers our economy, our health and well-being, our intellectual prowess, and our ability to innovate and compete. Shutting out Nature, the most significant relic of the creation of the universe, is like cutting out your eyes in order to become an art critic. You can talk about art, and I wager there will be people who listen to you, but can you truly understand it if you cannot see?
Be humble before Nature, but have the courage to question your assumptions and the responsibility to learn how to answer your questions. This is really what college is all about – not just about filling your heads with facts – and in the end the ability to think will serve you better than any skill in life.
