Our colloquium guest this week was Professor Michael Kruger from the Department of Physics. At a very early age, Dr. Kruger was inspired by a passion for finding answers to questions that intrigue all of us when we are young. According to Thoreau, we all start off very curious but somehow end up losing our interest as we grow up. Dr. Kruger knew that he wanted to be a physicist when he learned about Einstein’s Theory of Relativity in third grade. This intrigued him because Einstein was able to come deduce widely accepted and proved theories by simply contemplating everyday phenomena.
At the age of 16, Einstein asked, “What would I see if I looked in a mirror while traveling at the speed of light?” This is an interesting question because if Einstein was traveling at the speed of light that would mean that the photons of light producing the image and Einstein would be traveling at the same speed. At the age of 26, Einstein finally answered this question by concluding that it makes no difference—whether standing still or accelerating at the speed of light, his reflection would be the same.
This lead Einstein to develop two postulates that are experimentally possible but may sound counterintuitive upon first glance. The first postulate states that the laws of physics must stay constant in all inertial reference frames. So no matter where you go or how fast you go the laws of physics apply. The second postulate states that the speed of light in a vacuum has the same speed as light outside of a vacuum—the speed of light is constant. This may seem counterintuitive because the velocities of particles moving slower than the speed of light are relative, but light moves so fast that its speed is constant and absolute.
Further implications of the aforementioned postulates include time dilation and length contraction. Time dilation refers to the absence of a universal clock. In other words, time passes differently for objects at rest and for accelerating objects. This has been proven experimentally—subatomic particles take longer to decay when they are moving at the speed of light. Length contraction refers to the physical deformation of an object. For example, when accelerated at the speed of light, a baseball will change shape from a sphere to a disk.
Lastly, Dr. Kruger spoke about the infamous E=mc² derivation. While many of us have heard of this equation, its primary implication evades us. That is to say, behind this elegant equation lies the suggestion that any mass is a compact form of energy. If all the mass in an object as small as a paper clip (1 gram in mass) was converted to energy, it would equal 568,000 gallons of gasoline. This is why nuclear fusion is such an appealing aspect of research because the more it is understood, the more efficient and versatile our energy resources become.
Dr Kruger finished with a brief summary of his research—high pressure physics. In his laboratory, he uses a diamond to expose substances to pressures exceeding one million atmospheres. The center of the earth is 3.6 million atmospheres and this is what creates the magnetic field of the earth. The iron in the earth’s core turns into liquid metal which creates such a field. In contrast, Jupiter has no metals in its core yet it has a magnetic field. This is because Jupiter heats and compresses hydrogen into liquid metallic form to create a magnetic field. These compression experiments can also be used to freeze water at room temperature and synthesize diamonds from graphite.
To end the discussion, Dr. Kruger shared with us quotes from Einstein reminding us that, “Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”
~Nazanin Y