Most students are so preoccupied enough with classes, schoolwork and extracurriculars that they cannot escape their immediate surroundings. However, for Brian Greene, his work places him in the cosmic realm on a daily basis, transcending the world, the galaxy and even the universe. Greene, a professor of physics and mathematics at Columbia and a leading expert on string theory, delivered a lecture Tuesday titled "The Fabric of the Cosmos" at the DeBartolo Performing Arts Center.
Greene has published three books written for a non-scientific audience, which he drew material from for Tuesday's lecture.
Greene cited Einstein's theory of general relativity as the foundation of today's work in the cosmic arena. Using the analogy of a rubber sheet, Greene explained general relativity in terms of the physical observations gleaned from gravity. He said warps created by an object with mass, such as a bowling ball, parallel those in space and time itself, creating the gravitational force we know.
"Imagine space and all around us, envisioning an astronomical body like the sun warping the fabric of space just by virtue of its presence in it, changing the trajectory of objects around it," he said. "The moon is kept in orbit because in a sense, it's rolling along a valley in the curved environment [in the rubber sheet] that the earth creates. This means that at the deepest levels of our understanding of the cosmos, space and time are vital participants, not just the stage on which events take place."
According to this theory, Greene said black holes are warps so steep, not even light can escape. He said in effect they are masses so compact they create nearly vertical vortexes.
"One very specific puzzle that black holes have raised is the question of what happens if I take an object and throw it into a black hole," Greene said. "One of the very basic principles of physics is that the data in any object, everything from its appearance to the distribution of the molecules and atoms that make it up, cannot fundamentally be lost. If a black hole were to actually eat information and it was permanently gone from the universe, it would violate this law and ultimately wreak havoc on our fundamental equations of quantum mechanics."
The widely accepted solution to this problem has fantastic implications for the conventional understanding of our very existence, Greene said.
"We now believe that when an object crosses the edge of a black hole and falls in, the information it contains gets ‘smeared out' over the surface of the black hole and that the bits of information on the surface are in principle retrievable," he said. "The two-dimensional version of the object that is smeared out on the surface has a three-dimensional counterpart inside the space of the black hole."
Because the spatial environment within a black hole is governed by the same laws of three-dimensional space, Greene said it is probable the environment we inhabit can also be described by two-dimensional information at the very edge of the observable universe. He compared this to a holograph.
"Not only do objects in a black hole have a holographic description, but so do we in the two-dimensional surface surrounding the universe," Greene said. "A sort of binary code can contain a fundamental description of everything we see, so everything we perceive is, in some sense, just an illusion."
Continuing his examination of the expansion of space, Greene addressed the always-transient nature of our observational capacity and the effect this may have on future discovery. He said the increasing expansion speed of the universe means one day the other galaxies will be beyond our observational capacity.
"Now, we can examine faint pinpoints of starlight from distant galaxies, but in the future those galaxies will be rushing away faster than the speed of light," Greene said. "This means we won't be able to see them because they'll be going faster than light can show us."
Greene said he sees this as a source of urgency in physics today.
"We are living in a remarkable era when answers are in reach, which may not always be the case," he said. "Sometimes, nature guards her secrets with the unbreakable grip of physical law, but sometimes the true nature of reality beckons to us from beyond the horizon."
The most important thing this generation's scientists can do is retain their childlike wonder, Greene said.
"It's so important not to lose what you already have; we all begin life as little scientists smashing things together to figure things out," he said. "A successful scientist goes into the unknown not afraid of being right or wrong, but giving it an uninhibited shot. The great scientists are the ones who don't lose their childlike wonder and willingness to explore."
