The increase of disorder or entropy is what distinguishes the past from the future, giving a direction to time.
Stephen Hawking – A Brief History of Time
Direction of Time
D
Unified Theory
U
Even if there is only one possible unified theory, it is just a set of rules and equations.
Stephen Hawking – A Brief History of Time
Universe’s Boundary
U
The boundary condition of the universe…is that it has no boundary.
Stephen Hawking – A Brief History of Time
Equations and Sales
E
Someone told me that each equation I included in the book would halve the sales.
Stephen Hawking – A Brief History of Time
Time Travel
T
Time travel used to be thought of as just science fiction, but Einstein’s general theory of relativity allows for the possibility that we could warp space-time so much that you could go off in a rocket and return before you set out.
Stephen Hawking – A Brief History of Time
Human Spirit
H
To confine our attention to terrestrial matters would be to limit the human spirit.
Stephen Hawking – A Brief History of Time
Nature of the Universe
N
We find ourselves in a bewildering world. We want to make sense of what we see around us and to ask: What is the nature of the universe? What is our place in it?
Stephen Hawking – A Brief History of Time
Gradual Realization
G
The whole history of science has been the gradual realization that events do not happen in an arbitrary manner.
Stephen Hawking – A Brief History of Time
Survival of Humanity
S
Although September 11 was horrible, it didn’t threaten the survival of the human race, like nuclear weapons do.
Stephen Hawking – A Brief History of Time
Universe’s Beginning
U
It is not necessary to invoke God to light the blue torch paper and set the universe going.
Stephen Hawking – A Brief History of Time