Gravitational Waves Quotes

“Famously, Einstein said that his ‘happiest thought’ occurred here: ‘I was sitting in a chair in the Patent Office at Bern when all of a sudden a thought occurred to me. If a person falls freely he will not feel his own weight. I was startled.’ By thinking of someone falling, for example in a plummeting lift, Einstein had realised that it was impossible to distinguish acceleration and the pull of gravity. And working through the mathematical implications of this made it clear that gravity was an effect that could be produced by a distortion of space and time.”
― Brian Clegg, Gravitational Waves: How Einstein's spacetime ripples reveal the secrets of the universe

“Newton’s law of gravitation. That’s all you need (with a spot of calculus to crunch the numbers) to work out how the Earth will orbit the Sun or how an apple will fall if you let it go at a certain height. The only trouble is that Newton had no idea how this gravity thing worked. His model was simply: ‘There is an attraction between bits of stuff, and let’s not bother about why.”
― Brian Clegg, Gravitational Waves: How Einstein's spacetime ripples reveal the secrets of the universe

“gravitational waves are fundamentally different. Not only is a gravitational wave a side-to-side, lateral wave like light, not a longitudinal wave like sound, but it isn’t a ripple through objects in spacetime; it passes through spacetime itself. When a gravitational wave passes by, spacetime squeezes and contracts. This oscillation influences matter, which exists in spacetime – but doesn’t require matter to be able to travel. It’s quite demeaning to gravitational waves to call their detection ‘hearing the sound of black holes in space’ as some have done. By comparison, sound is a trivial local effect. Gravitational waves make the universe itself vibrate.”
― Brian Clegg, Gravitational Waves: How Einstein's spacetime ripples reveal the secrets of the universe

“why Newton’s apple fell. The apple isn’t moving at all at the start of the process, so why would changing the shape of space make it move? The wonderful answer is that massive objects don’t just warp space, they warp space and time. In Einstein’s world, space and time are united into the single entity, spacetime. In principle we should think of spacetime as a four-dimensional object – but that’s hard to envisage, so what we tend to do is to just use two space dimensions and one of time. (The third space dimension hasn’t gone away, we just don’t need to think of it.) When we speak of warping space or time, what happens is that the axis is no longer straight, but starts to curve.”
― Brian Clegg, Gravitational Waves: How Einstein's spacetime ripples reveal the secrets of the universe

“So, for instance, even though the Earth is travelling in a straight line through space, space itself is curved, so the planet orbits the bowling ball of the Sun. It is a simple, but astonishing observation. Planets move in straight lines. There really is no force pulling them into an orbit. It’s just that the space their straight line path runs through gets twisted.”
― Brian Clegg, Gravitational Waves: How Einstein's spacetime ripples reveal the secrets of the universe

“Imagine we’re in a spaceship moving steadily through space and we throw a ball across the ship from side to side. It will move in a straight line, because both the ball and the ship are moving forwards at the same speed. But if the ship accelerates, the ball’s path will become curved, as the ship moves ahead more quickly. The straight line path has become curved from the viewpoint of the ship. Similarly, Einstein reasoned, a straight line path in space would be curved by gravity.”
― Brian Clegg, Gravitational Waves: How Einstein's spacetime ripples reveal the secrets of the universe

“The work of Max Planck, Albert Einstein, Niels Bohr and others showed that light appeared to be both a wave and a stream of particles. Although it was convenient for many purposes to think of light as behaving like a wave, the particle idea explained more phenomena. As the great American physicist Richard Feynman would later put it: ‘It is very important to know that light behaves like particles, especially for those of you who have gone to school, where you were probably told about light behaving like waves. I’m telling you the way it does behave – like particles.”
― Brian Clegg, Gravitational Waves: How Einstein's spacetime ripples reveal the secrets of the universe

“The remarkable Scottish physicist James Clerk Maxwell worked out in the early 1860s that light was an interaction between electricity and magnetism. And this meant that in principle, you could have an electric wave creating a magnetic wave, creating an electric wave and so on, hauling itself through empty space by its own bootstraps without any material medium required – it is the electromagnetic field that acts as the material.”
― Brian Clegg, Gravitational Waves: How Einstein's spacetime ripples reveal the secrets of the universe

“Imagine simultaneously dropping two stones, a few centimetres apart, into a still pond. The ripples – waves – that the stones create will head outwards from the two locations that the stones hit the water until those waves meet. When they do, there will be points on the surface of the water where both waves are rippling in the same direction (up or down) at the same time. Here, the waves will reinforce each other, becoming stronger than before. At other points on the surface, the waves will be rippling in opposite (vertical) directions at any point in time. Here the waves will cancel each other out, leaving relatively still patches of water. This effect, producing a distinctive pattern on the surface, is known as interference.”
― Brian Clegg, Gravitational Waves: How Einstein's spacetime ripples reveal the secrets of the universe

“When you speak to someone, your vocal cords start a compression wave in the air that spreads out from your mouth until those compressions and rarefactions reach the listener’s ear. There, they vibrate the hair-like structures in the ear, producing the sensation of hearing. But the link between you and the listener is the longitudinal waves that pass through the air.”
― Brian Clegg, Gravitational Waves: How Einstein's spacetime ripples reveal the secrets of the universe

“Transverse waves usually have to travel along the edge of the medium – for example, on the top of the water that the wave passes through. For a longitudinal wave, the regular cycle is in the same direction as the wave moves forward, not at right angles. The medium is repeatedly squashed up and relaxed like a concertina, so what travels through it is a pattern of compression and rarefaction.”
― Brian Clegg, Gravitational Waves: How Einstein's spacetime ripples reveal the secrets of the universe

“Think of a Mexican wave travelling around a stadium (a Mexican wave is a transverse wave as the cycle of the motion is up and down, while the wave travels at right angles to that direction, round the stadium). The medium here is the mass of spectators who bob up and down. But they stay in their seat positions”
― Brian Clegg, Gravitational Waves: How Einstein's spacetime ripples reveal the secrets of the universe