By Jonny Lupsha, Wondrium Staff Writer
Was the Big Bang really the beginning of time? The world-renowned periodical has published scientific reading material for nearly 180 years. In a new series, Wondrium and Scientific American answer the big questions of time.
Is time an illusion? Could time end? Is traveling back in time possible under any circumstance? Questions like these have left humanity scratching its head for centuries. All of them are addressed in Wondrium’s series Examining the Big Questions of Time, which is developed in partnership with Scientific American.
One of the most surprising, ongoing debates is whether the Big Bang marked the beginning of time. Decades ago, the matter seemed settled. Now, due to the development of ideas in theoretical physics such as string theory, scientists are rethinking the matter. Laura Helmuth, editor-in-chief of Scientific American, examines this debate in this mind-expanding collaboration between our two companies.
Quarks on Strings
If the Big Bang wasn’t the beginning of time, what was? In order to answer this question, Helmuth said that physicists need to “include relativity in a quantum theory of gravity.” In other words, gravity is the least understood fundamental force and in order to develop a proper theory of it based in quantum physics, the theory of relativity should be included.
“Today, two approaches stand out: One is called ‘loop quantum gravity,’ and it retains Einstein’s theory essentially intact, but it changes the procedure for implementing it in quantum mechanics,” she said. “Practitioners of loop quantum gravity have taken great strides and achieved deep insights over the past several years. Still, their approach may not be enough to resolve the fundamental problems of quantizing gravity.”
The second approach is string theory, which grew from a model introduced in 1968 by physicist Gabriele Veneziano. Veneziano wrote about nuclear particles—protons and neutrons—and their interactions. His idea was improved upon by the model of quantum chromodynamics, which broke nuclear particles down even further into elementary constituents called quarks, which are confined in protons or neutrons as though tied together by elastic strings. It was revisited later, combining general relativity and quantum theory.
“The basic idea is that elementary particles are not point-like but rather infinitely thin, one-dimensional objects, and these are the strings,” Helmuth said. “So, the zoo we know of elementary particles, each of which its own characteristic properties, those reflect the many possible variation patterns of a string.
“Once the rules of quantum mechanics are applied to a vibrating string—just like a miniature violin string, except that the vibrations propagate along it at the speed of light—once that happens, new properties appear, and all of these have profound implications for particle physics and for cosmology.”
Bear with Me; We’re Getting There
Bringing the discussion back to the beginning of time, string theory offers one answer to a difficult question about a concept known as the initial singularity or Big Bang singularity.
Since the universe is expanding, we can assume that if we rewound the universe, it would shrink. Many consider the point at which all galaxies come together in an infinitesimal point to be both the Big Bang and the beginning of time. This is the initial singularity.
“Quantities such as density, temperature, and spacetime curvature all become infinite—the singularity is the ultimate cataclysm, beyond which our cosmic ancestry cannot extend,” Helmuth said.
Yet, this singularity poses massive problems for cosmologists. In order for so much of the universe to look the same, as it does, some kind of communication must have passed among distant regions of space, like a cosmic version of every student in class calling one another and coordinating to wear the same outfit at school the next day.
Only instead of clothes, it’s identical patches of sky known as cosmic microwave background (CMB) radiation, which is the aftermath of the Big Bang. And instead of 20 to 30 kids in one class, it’s tens of thousands of students. This communication does not gel with the idea of the Big Bang being the beginning of time. Why?
“All the magic properties of quantum strings point in one direction: strings abhor infinity,” Helmuth said. “They can’t collapse to an infinitesimal point, so they avoid the paradoxes that collapse entails. String theorists expect that when you play the history of the universe backward in time, the curvature of spacetime starts to increase, but instead of going all the way to infinity—which is the traditional Big Bang singularity—it eventually hits a maximum and then shrinks again.”
Several theories about the pre-Bang universe have begun to arise.
Examining the Big Questions of Time is now available to stream on Wondrium.