Explaining Everything, Explaining Anything

The following are reflections on this year’s Mini-Beatty Public Lecture “Life, the Universe and Nothing: A Cosmic Mystery Story” held by Dr. Lawrence M. Krauss held on March 1st, 2010 at McGill University.

Edwin Hubble via Vision.

Science and its academic disciplines have shaped and transformed our modern world arguably more so than any other force. Despite this, there still remains a large chasm between the public’s perception of and the reality of the scientific method and the epistemology of science. Public intellectuals such as Carl Sagan and Richard Feynman have sought to bridge this gap by using their background as scientists and ability as writers and orators. Earlier this month, I had the opportunity to listen to Dr. Lawrence Krauss, physicist, director of the Origins Initiative at Arizona State University and best-selling author speak about the nature of science with respect to the development of theories about the universe.

Reaching the starting place

Dr. Krauss, whose exceptionally lucid speaking and writing style places him among the great modern public intellectuals, set the tone of the lecture with a quote by the American poet Louise Bogan: “The initial mystery that attends any journey is how did the traveler reach his starting point in the first place?” The starting point of the universe is one of the mysteries that has perplexed scientists for years.

After figuring out that the universe was not static, early modern physicists sought to find the precise age of the universe. Edwin Hubble, who described the expanding universe, predicted the age of the universe to be 1.5 billion years. However, this was problematic and paradoxical at the time, since scientists were aware that the age of the Earth was much older than 1.5 billion years.

Uncertainties are an inevitable part of science, and knowledge that known unknowns and unknown unknowns exist is what pushes research forward. Seeking to determine a more accurate age for the universe, later observational data improved on measurements of the distance between galaxies, obtaining a closer estimate of 13.75 billion years. These improvements include standard candles obtained from supernovae.

The House of Cards

In his lecture, Dr. Krauss said that he considers one of the biggest misconceptions about science to be that scientists want to be right, remarking humorously, “They don’t want to be wrong, but they want their colleagues to be wrong.” He highlighted the nature of science as one where theories are constantly proven wrong, and new ideas emerge to replace old ideas.

Several examples of this evolving process were evoked throughout the lecture. One of these was the debate regarding the nature of universe as quasi-static verses expanding. Einstein, the father of modern physics, subscribed to the notion of a quasi-static cosmos which held the universe to be a dynamically stable and infinite system. As early as 1917, however, other physicists and astronomers were critical of this view noting that Einstein’s formulas did not present any evidence for this. Based on observational data, other physicists began to present evidence instead that the universe is changing, expanding.

In the 1920s Edwin Hubble outlined comprehensive evidence for the expansion of the universe based on a decade of measuring of red-shift velocities of galaxies. He realized that every galaxy was moving away at a speed proportional to its distance from us. This meant that the universe had a discernable genesis, and strongly supported the big bang and the model of an expanding universe—disproving the static model of the cosmos.

Today, modern physics is a house of cards built on two principles, special relativity and quantum mechanisms, which accurately describe physical phenomena, but appear to be irreconcilable with one another. Reflecting on the persisting challenges facing theoretical physics Dr. Krauss described the public misconception of scientific theories, and affirmed an integral component of the scientific method: “You cannot prove a theory, you can only disprove it.”

Jigsaw Falling into Place

The most compelling aspect of the lecture by Dr. Krauss was his discussion of the nature of the material in the universe. Efforts to uncover the nature of the material in the universe, and weigh it all, began in the post-renaissance era of astronomy, in the observatories of people like Tycho Brah.

Einstein’s Field Equations (EFEs), published in 1915, were the most comprehensive set of mathematical equations to describe the nature of the universe. These set of ten equations describe the curvature of space-time by matter and energy:

On the left side is the Einstein tensor, describing space and time; and on the right side is the stress-energy tensor, describing energy and momentum.

Using these equations, and later postulations about the conformation of the universe as flat, open or closed, physicists have been able to approximate Ωm which is the matter density of the universe. Matter itself appears to be of an enigmatic nature, Dr Krauss said that in fact most of the mass of protons is not due to steady quarks, “but virtual particles that pop in and out of existence.” What is even more perplexing, Dr. Krauss noted, is that ordinary matter has been calculated to make up only about 5% of the total mass-energy of the universe. In fact in the flat universe model, the energy of empty space makes up to 70% of all energy in the universe.

Dark matter and dark energy have been theorized to resolve these discrepancies. Dark matter is thought to be a substance composed not of protons and neutrons, but of exotic weakly interacting particles that are undetectable by us. Dark energy is thought to be a repulsive force in space that allows the universe to expand at an exponential rate. Physicists and astronomers are still exploring the nature of dark matter and dark energy, whether they do in fact exist, and how they shape our universe.

In this lecture, Dr. Krauss encouraged the audience to look at the body of scientific knowledge critically, and always leave space for the possibility that we, as scientists, may be wrong. In fact, he described the whimsical possibility that in a trillion years, the cosmic microwave background (CMB) radiation will have faded, and it is possible that dark energy will have disappeared—and for those humans who may look to unravel the secrets of the universe then, based on the evidence, they may return to the inaccurate model of a static universe.

However, the possibility that we too may never reach objective truths about the universe has not dissuaded scientists from trying. As Dr. Krauss has remarked in the past, “Scientists love mysteries. They love not knowing.” Indeed, that mystery, knowing something is out there waiting to be unraveled is what drives me as a scientist-in-training. After all, the history of science is one of ebbs and flows, one of failures and success, but most of all a constant struggle to grasp a jigsaw piece of truths hidden a universe of smoke and mirrors.