A Brief History of Genius: 5 Brilliant Ideas about the Universe
The man with the voice of a robot and a mind as vast as the universe. Stephen Hawking was the embodiment of curiosity, and his work was the spark that fired up the imaginations of millions, conjuring up visions of space and its origins. Hawking’s visionary genius unified many different fields of physical theory — gravitation, cosmology, quantum theory, thermodynamics, and information theory — to answer some of humanity’s basic questions. Namely: Why does the universe exist? What will it look like in the future?
In his record-breaking, bestselling book A Brief History of Time, Hawking illuminates these mysteries of the universe for those who might see physics as a confusing complex of theories and equations, by describing, in layman’s terms, the laws which govern it.
If you, too, have ever wondered how the universe began, why we see time as going forward, and what quantum mechanics and black holes actually are, hang in there. In honor of Hawking’s unstoppable quest for breaking down the barriers between people and scientific discovery, here are 5 of his most exciting ideas about the universe.
1. The Origin of the Universe
This was Stephen Hawking’s first major discovery. In 1970, Hawkings and Roger Penrose used mathematics to demonstrate the existence of black holes and to show that the first moment of our universe, the Big Bang, came from a tiny bend in what we know as the fourth dimension — spacetime.
The work that Roger Penrose and I did between 1965 and 1970 showed that, according to general relativity, there must be a singularity of infinite density and spacetime curvature within a black hole. This is rather like the Big Bang at the beginning of time.
2. Black Holes
Even though he did not discover black holes, Hawking’s studies transformed the way we see them. In A Brief History of Time, he describes spacetime as a sheet of rubber, which could be bent by a heavy orb, like a star or planet. When a star or planet of considerable mass dies, it collapses into a singularity, a bottomless hole of infinite density, where everything, even light, bends. This is how a black hole forms.
3. Black Holes Ain’t So Black
A black hole’s outer border is called the event horizon. The event horizon is the point at which gravitational pull becomes so incredibly powerful, that nothing can escape it. Hawking found that there are pairs of virtual particles around black holes’ event horizons. Virtual particles are ones which we can’t see, but whose effects we can measure.
As it turns out, black holes absorb the negative particles, but the positive ones manage to stay outside of the event horizon’s point of no return. These particles that get away create what we now call ‘Hawking radiation’, the electromagnetic emissions that show that black holes not only absorb but also release things. The inward flow of negative particles into the black hole can ever so slowly reduce its mass until eventually it evaporates and dies in a spectacular, Armageddon-esque explosion.
Look up at the stars and not down at your feet. Try to make sense of what you see, and wonder about what makes the universe exist. Be curious.
4. The Arrows of Time
In the ninth chapter of his book, Hawking talks about how we humans observe and perceive time as having one direction – from the past towards the future. This is dictated by the three arrows of time.
The Thermodynamic Arrow of Time
This one is based on the second law of thermodynamics, which says that entropy, the level of disorder in a system, can only increase over time. This is why, for example, you never see the broken pieces of a cup gather themselves together to form a whole cup, but rather, you see the cup dangerously close to the edge of the table, and your playful cat slowly pushing it to its terrible fate.
The Psychological Arrow of Time
The second arrow is the psychological arrow of time. Our psychological sense of time moves in one direction, which is why we remember the past and not the future. We never see it work in the opposite direction.
The Cosmological Arrow of Time
Lastly, there is the cosmological arrow of time. Hawking states that, in order for us to observe and experience the first two arrows of time, the universe would have to begin in an orderly state, and start its expansion from there, becoming increasingly disorderly. Boom! If you’ve been paying attention, you probably realized that the thermodynamic arrow now matches the cosmological arrow.
Hawking states that humans experience these arrows of time because we have been living in the expanding phase of the universe. This is the ideal state for intelligent beings to exist, because of its strong thermodynamic arrow. According to him, intelligent life could not exist in a contracting universe. Hawking calls this the “weak anthropic principle.”
5. The Unified Theory of Physics
Stephen Hawking was the first scientist to combine theories of quantum physics with general relativity. This drove him towards looking for a ‘grand unified theory’ which would pretty much describe how everything works in our universe. In A Brief History of Time, he concluded: “It would be the ultimate triumph of human reason – for then we would know the mind of God.” While both theories provide great insights, there are remarkable differences in what they predict and observe, making them incompatible. However, Hawking believed that by studying the very early stages of the universe in a lab, we would finally find a complete unified theory in the 21st century.
He once famously declared: “My goal is simple. It is a complete understanding of the universe, why it is as it is and why it exists at all.” Hawking’s findings have driven theoretical physics forward for the last couple of decades, because the three fundamentals of physics—general relativity, quantum mechanics, and thermodynamics—all coalesce in his work, hinting at a deeper unified theory. As we continue to explore the bounds of reality, we need to look back and take our hats off to the man who blazed a trail in his motorized wheelchair.