The river of time may fork into rivers, in which case you have a parallel reality and so then you can become a time traveler and not have to worry about causing a time paradox.

When you come up with a theory, you fall in love with the beauty the simplicity and elegance of it. But then you have to get a sheet of paper and pencil and crack out all the details. Hundreds and hundreds of pages. Because you have to prove it.

Science fiction without the science just becomes, you know, sword and sorcery, basically stories about heroism and not much more.

To a physicist, we have the 'I' word, the I-word is 'impossible.' That's dangerous.

You cannot create new science unless you realize where the old science leaves off and new science begins, and science fiction forces us to confront this.

The job market of the future will consist of those jobs that robots cannot perform. Our blue-collar work is pattern recognition, making sense of what you see. Gardeners will still have jobs because every garden is different. The same goes for construction workers. The losers are white-collar workers, low-level accountants, brokers, and agents.

I vowed to myself that when I grew up and became a theoretical physicist, in addition to doing research, I would write books that I would have liked to have read as a child. So whenever I write, I imagine myself, as a youth, reading my books, being thrilled by the incredible advances being made in physics and science.

No one knows when a robot will approach human intelligence, but I suspect it will be late in the 21st century. Will they be dangerous? Possibly. So I suggest we put a chip in their brain to shut them off if they have murderous thoughts.

Global warming is actually a misnomer. It should be global extremes and global swings, because you add - as you add more energy into the atmosphere, it sloshes around. Energy doesn't simply uniformly warm up the planet. And that means droughts in one area, enormous snowstorms in another area, 100-year floods here, 100-year forest fires there.

Until computers and robots make quantum advances, they basically remain adding machines: capable only of doing things in which all the variables are controlled and predictable.

Remember the movie 'The Matrix,' where virtual information popped up to help inform physical day-to-day reality? Such things won't always be the stuff of Hollywood. If the Internet is accessible via contact lenses, biographies will appear next to the faces of the people we talk to, and we will see subtitles if they speak a foreign language.

We're in 'Jurassic Park' territory. If we go to the zoo in the future, we'll have zoos for extinct animals.

In science, nothing is ever 100% proven.

Our astronauts, when they go orbiting around the earth, they actually come back slightly younger than a twin that they would have on the planet Earth who was stationary. This is called the twin paradox.

It turns out that the left temporal lobe, if there's a lesion there, will create hyper-religiosity. People become super-religious. They see demons and spirits everywhere. We think Joan of Arc may have had it.

I like to engage the public because when I was in high school, I had all these questions about anti-matter, higher dimensions and time travel. Every time I went to the library, every time I asked people these questions, I would get some strange looks. Nobody could answer any of these questions.

It's inevitable that we'll have some form of designer children, fueled not just by the science but by parents' hard-wired desire to give their children every advantage.

If you want to see a black hole tonight, tonight just look in the direction of Sagittarius, the constellation. That's the center of the Milky Way Galaxy and there's a raging black hole at the very center of that constellation that holds the galaxy together.

I have nothing against investment banking, but it's like massaging money rather than creating money. If you're in physics, you create inventions, you create lasers, you create transistors, computers, GPS.

Democracies are slow to anger and hesitant to go to war: Voters don't want to sacrifice their children for the glory of a selfish king.

We can summarize electricity, magnetism and gravity into equations one inch long, and that's the power of field theory. And so I said to myself: I will create a field theory of strings. And when I did it one day, it was incredible, realizing that on a sheet of paper I can write down an equation which summarized almost all physical knowledge.

In the future, the Internet might become a 'brain net' where we send memories, feelings and sensations.

Even if we mortgage the next 100 years of generations of human beings, we would not have enough energy to build a Death Star.

Humans are natural-born scientists. When we're born, we want to know why the stars shine. We want to know why the sun rises.

Virtual reality and augmented reality will change the way we shop.

It's pointless to have a nice clean desk, because it means you're not doing anything.

If we do get a quantum theory of spacetime, it should answer some of the deepest philosophical questions that we have, like what happened before the big bang?

For relaxation, I like to figure skate. Being on the ice and spinning and jumping, I feel very close to nature. In particular, I feel very close to Newton's laws of motion. On the ice, you can experience Newton's laws of motion in their purest, most elegant form.

The universe is a symphony of strings, and the mind of God that Einstein eloquently wrote about for thirty years would be cosmic music resonating through eleven-dimensional hyper space.

I think the 'Terminator' idea is a reasonable one - that is that one day the Internet becomes self-aware and simply says that humans are in the way. After all, if you meet an ant hill and you're making a 10-lane super highway, you just pave over the ants. It's not that you don't like the ants, it's not that you hate ants; they are just in the way.

You have to have a cultural ethic that allows for making mistakes. It cannot be that just because you make mistakes, you're out. You have to make mistakes in order to innovate.

I think Newton would be the greatest scientist who ever lived.

A lot of the things you see in science fiction revolve around black holes because black holes are strong enough to rip the fabric of space and time.

Technologies that may be realized in centuries or millennium include: warp drive, traveling faster than the speed of light, parallel universes; are there other parallel dimensions and parallel realities? Time travel that we mentioned and going to the stars.

To me, it is clear that we exist in a plan which is governed by rules that were created, shaped by a universal intelligence and not by chance.

The media, of course, loves to make claims about the fountain of youth. Don't believe it. No one has it. But we're getting close.

I confess I sometimes sneak a peek at 'The Big Bang Theory.' I chuckle at their antics. But I cringe when they portray physicists as clueless nerds who are doormats when it comes to picking up women.

Chemistry is the melodies you can play on vibrating strings.

One day when I was 8 years old, everyone was talking in hushed tones about a great scientist that had just died. His name was Albert Einstein.

If space is a fabric, then of course fabrics can have ripples, which we have now seen directly. But fabrics can also rip. Then the question is what happens when the fabric of space and time is ripped by a black hole?

When we're born, we want to know why the stars shine. We want to know why the sun rises.

I'm not a science fiction writer, I'm a physicist.

A force field is basically an invisible shield. You push a button and all of a sudden a bubble forms around you which is impenetrable. It can stop bullets, it can stop ray gun blasts and we realized force fields are actually a little bit difficult to create.

If a Martian came down to Earth and watched television, he'd come to conclusion that all the world's society is based on Britney Spears and Paris Hilton. He'd be amazed that our society hasn't collapsed.

The Internet frees people to realize they don't have to live like slaves.

Sooner or later, we will face a catastrophic threat from space. Of all the possible threats, only a gigantic asteroid hit can destroy the entire planet. If we prepare now, we better our odds of survival. The dinosaurs never knew what hit them.

I predict that technology will enable people to transmit their neuronal, actual feelings over the Internet.

What we usually consider as impossible are simply engineering problems... there's no law of physics preventing them.

The human brain has 100 billion neurons, each neuron connected to 10 thousand other neurons. Sitting on your shoulders is the most complicated object in the known universe.