Stranger Than We Can Imagine Read Online Free Page A

heart can be grasped surprisingly easily.
    Imagine the deepest, darkest, emptiest chunk of space possible, far removed from stars, planets or any other influence. In this deep void imagine that you are floating, snug and warm in a space suit. Importantly, imagine that you are not moving.
    Then imagine that a cup of tea comes slowly floating past, and eventually disappears into the distance.
    At first glance, this scenario sounds reasonable. Newton’s First Law says that an object will continue to remain at rest, or will move in a straight line at a constant velocity, unless some external force acts on it. Clearly, this is a perfect description of the behaviour of both you and the cup of tea.
    But how could we say that you were at rest? Einstein would ask. How do we know that it’s not the cup of tea that’s at rest, and youthat are moving past it? Both situations would appear identical from your point of view. And also, from the point of view of the cup of tea.
    Galileo was told in the 1630s that it wasn’t possible the earth was going around the sun, because we on earth do not feel like we are moving. But Galileo knew that if you were moving smoothly, without accelerating or decelerating, and if there were no visible or audible clues to movement, then you would not be aware of your motion. He argued that you cannot claim to be ‘at rest’, because it is impossible to tell the difference between a moving object and a stationary one without some form of external reference to compare it against.
    This may sound like a dubious, pedantic point. Surely, you might think, you are either moving or not moving, even if there’s nothing else around. How could anyone claim that the statement ‘you are at rest’ is absurd or meaningless?
    Schoolchildren are taught to plot the position of objects by drawing diagrams that show their distance from a fixed point in terms of height, length and depth. These are called the x, y and z axis, and the fixed point is usually called O or the origin. This is an omphalos, from which all the other distances are measured. The territory marked out by these x, y and z axes is called Cartesian space. In this framework, it would be simple to tell whether the astronaut and the cup of tea were static or moving by noting whether their coordinates in Cartesian space changed over time.
    But if you had shown that illustration to Einstein he would have leant over with an eraser and removed the origin, and then rubbed out the x, y and z axis while he was at it.
    He wouldn’t be deleting ‘space’ itself. He would be removing the frame of reference that we were using to define space. He would do this because it was not a feature of the real world. That framework of Cartesian space is a product of our minds, like the longitude lines stretching away from Greenwich, which we project onto the cosmos in order to get a grip on it. It does not really exist. Also, it is arbitrary. That framework could have been centred anywhere.
    Instinctively we feel that we or the tea must be moving – or not – against some form of definitive ‘background’. But if there is a definitive background, what could it be?
    In our everyday lives the solid ground beneath our feet is a point of reference that we unconsciously judge everything by. Living with such a clear fixed point makes it hard to imagine one not existing. But how fixed is the ground? We have known that continents are slowly moving since the acceptance of plate tectonics in the 1960s. If we are seeking a fixed point, it is not the land that we stand on.
    Could we instead define our position with the very centre of the earth? This isn’t fixed either, because the earth is moving around the sun at over 100,000 km/h. Or perhaps we can define the sun as our fixed point? The sun is moving at 220 km/s around the centre of the Milky Way galaxy. The Milky Way, in turn is moving at 552 km/s, relative to the rest of the universe.
    What of the universe itself? As a