Alan Guth Quotes

In Einstein's general relativity the structure of space can change but not its topology. Topology is the property of something that doesn't change when you bend it or stretch it as long as you don't break anything.

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 you're falling through space time has no meaning.

In curved Einsteinian space we are at all times, technically, looking at the back of our own head.

You have to say now that space is something. Space can vibrate, space can fluctuate, space can be quantum mechanical, but what the devil is it?

Relativity challenges your basic intuitions that you've built up from everyday experience. It says your experience of time is not what you think it is, that time is malleable. Your experience of space is not what you think it is; it can stretch and shrink.

Before 1915, space and time were thought of as a fixed arena in which events took place, but which was not affected by what happened in it. Space and time are now dynamic quantities... space and time not only affect but are also affected by everything that happens in the universe.

Most gravity has no known origin. Is it some exotic particle? Nobody knows. Is dark energy responsible for expansion of the universe? Nobody knows.

It's not completely obvious what gravity is, fundamentally, or what dimensions are, fundamentally. One of these days we'll understand better what we mean, what is the fundamental thing that's given us space in the first place and dimensions of space in particular.

Einstein's gravitational theory, which is said to be the greatest single achievement of theoretical physics, resulted in beautiful relations connecting gravitational phenomena with the geometry of space; this was an exciting idea.

It is theoretically possible to warp spacetime itself, so you're not actually moving faster than the speed of light, but it's actually space that's moving.

I always found it satisfying that gravity was described by Einstein's geometric theory of general relativity.

There may be many Big Bangs that happened at various and far-flung locations, each creating its own swelling, spatial expanse, each creating a universe - our universe being the result of only one of those Big Bangs.

A big misconception is that a black hole is made of matter that has just been compacted to a very small size. That's not true. A black hole is made from warped space and time.

One of the most exciting things about dark energy is that it seems to live at the very nexus of two of our most successful theories of physics: quantum mechanics, which explains the physics of the small, and Einstein's Theory of General Relativity, which explains the physics of the large, including gravity.

General relativity is the cornerstone of cosmology and astrophysics. It has also provided the conceptual basis for string theory and other attempts to unify all the forces of nature in terms of geometrical structures.

We're going to need a definitive quantum theory of gravity, which is part of a grand unified theory - it's the main missing piece.

I became interested in this question of whether you can build wormholes for interstellar travel. I realized that if you had a wormhole, the theory of general relativity by itself would permit you to go backward in time.

There was a long history of speculation that in quantum gravity, unlike Einstein's classical theory, it might be possible for the topology of spacetime to change.

Even in empty space, time and space still exist.

My work on black holes was on the connection between black holes and elementary particles.

The whole idea of gravity curling up space, that is the epitome of what is going on in a black hole. I would've loved to have seen Einstein's face if he were presented with the data that we actually discovered such a thing, because he himself probably didn't believe in much of it.

The field equations and the whole history of general relativity have been complicated.

When forced to summarize the general theory of relativity in one sentence: Time and space and gravitation have no separate existence from matter.

Bodies like the earth are not made to move on curved orbits by a force called gravity; instead, they follow the nearest thing to a straight path in a curved space, which is called a geodesic. A geodesic is the shortest (or longest) path between two nearby points.