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1-Page Summary of The Fabric of the Cosmos
Appearances Are Deceiving
In reality, things are not what they seem to be. The past is behind us and the future lies ahead of us. However, physics shows that time does not exist in the way we think it does. For example, eggs fall from counters because of gravity but a broken egg will never become an intact one again by falling up to the countertop.
For 30 years, Albert Einstein was trying to find a unified theory. Now that superstring theory may make it possible, our understanding of reality will change drastically. String theory suggests that the universe has many more dimensions than we are aware of (10 spatial and 1 temporal). Superstring theory needs 11 dimensions: 10 spatial and 1 temporal dimension.
Where and When
Time and space are intertwined. When you move from one place to another, you also move through time. Time is relative because it’s different in each location. You can’t measure time without knowing where you are on Earth, which means that we all experience the same amount of time differently depending on our locations.
Isaac Newton believed that space and time were absolute. Therefore, no matter who is measuring the distance between two things or how long something took to happen, if their instruments are accurate, they’ll get the same results.
Philosopher Gottfried Wilhelm von Leibniz had a different view of space than Isaac Newton. He thought that space was merely a way of talking about the position of one thing relative to another and that there would be no such thing as empty space. To think about objects without thinking about their relation to other things would make no more sense than trying to imagine an alphabet without letters.
In 1689, Newton gained the upper hand in this debate with an experiment. It was quite simple. Fill a bucket with water, hang the bucket on a rope, twist the rope as far as you can and let go. The bucket begins to spin. At first, the water stays flat even though the bucket is spinning. But as the bucket spins faster and faster, the water also starts to spin changing its shape so that it is high at edge and low in center of circle. This shows that space exists because if something changes position relative to other objects then there must be some sort of space between those objects for them to move relative to one another.
For more than 200 years, it seemed like Newton’s ideas were correct. He said that the water was spinning in relation to absolute space. Space itself is real and objects move in relation to it or stay still.
Yet there are challenges. For example, take an ice skater spinning on the ice. Take an arena that’s spinning around the ice skater who is standing still on the ice. From a spectator’s viewpoint, it seems like the skater is spinning and not the arena. But from another point of view (the skater), it seems like it’s actually the opposite—that it’s actually in reverse: that he or she is stationary while everything else spins around him or her.
Who can say whether either perspective is correct?
In the middle of the nineteenth century, Austrian physicist Ernst Mach presented a new argument. He suggested that perhaps Newton was wrong about water spinning with respect to absolute space. Perhaps it’s only spinning relative to other objects in the room or outside in nature or even deep space if this experiment were conducted there. Mach challenged Newton’s fundamental assumption by suggesting that motion is only observed when something moves relative to other matter in the universe.
The theory of relativity was largely influenced by the work of Ernst Mach. Einstein’s special theory of relativity eliminated Newton’s absolute space and time, finding that only light speed is absolute. The relative nature of space and time means that for someone moving very fast through space, time would slow down slightly compared to a person who isn’t moving at all. This has been proven in 1971 when atomic clocks took commercial flights around the world, registering less elapsed time than stationary clocks on earth did.
