Join Blinkist to get the key ideas from
Get the key ideas from
Get the key ideas from
A Brief History of Time
From the Big Bang to Black Holes
- Read in 21 minutes
- Audio & text available
- Contains 13 key ideas
Synopsis
A Brief History of Time (1988) takes a look at both the history of scientific theory and the ideas that form our understanding of the universe today. From big bangs and black holes to the smallest particles in the universe, Hawking offers a clear overview of both the history of the universe and the complex science behind it, all presented in a way that even readers who are being introduced to these ideas for the first time will understand.
Key idea 1 of 13
Theories based on what you’ve seen in the past can help predict the future.
You’ve probably heard of the theory of gravity or the theory of relativity? But have you ever paused to think what we really mean when we talk about theories?
A theory, in its most basic terms, is a model that accurately explains large groups of observations. Scientists collect data from observations they see in, for example, experiments, and use it to develop explanations of how and why phenomena happen.
For example, Isaac Newton developed the theory of gravity after observing many phenomena, from apples falling from trees to the movements of planets. Using the data he collected he was able to describe gravity in a theory.
Theories have two great benefits:
First, they allow scientists to make definite predictions about future events.
For example, Newton’s theory of gravity allowed scientists to predict the future movements of objects like planets. If you want to know, say, where Mars will be six months from now, it’s possible to predict this precisely using the theory of gravity.
Second, theories are always disprovable, meaning they’re open to reform if new evidence that doesn’t fit the theory is found.
For example, people once believed in the theory that everything in the universe revolved around the Earth. Galileo disproved this theory when he noticed moons orbit Jupiter; he could therefore show that actually not everything orbit the Earth.
So in effect, a single future observation can always invalidate a theory, no matter how reliable it seems at the moment. This means theories can never be proven correct, and this makes science a constantly evolving process.
Key ideas in this title
- Theories based on what you’ve seen in the past can help predict the future.
- In the 1600s, Isaac Newton revolutionized the way we think about how objects move.
- The fact that the speed of light is constant shows that you can’t always measure something’s speed relative to something else’s.
- The theory of relativity states that time itself is not fixed.
- Since one can’t make exact measurements of particles, scientists use something called quantum state to make predictions.
- Gravity is the result of massive objects curving the universe.
- When a star with a very high mass dies, it collapses into a singularity called a black hole.
- Black holes emit radiation, which can lead to their demise through evaporation.
- Although we can’t be sure, there are strong indicators that suggest that time can only move forwards.
- In addition to gravity, there are three fundamental forces in the universe.
- Although scientists believe that the universe started with the big bang, they are unsure of exactly how this happened.
- Physicists haven’t been able to unify general relativity and quantum physics.
- Final Summary
