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The birth of newtons law and the principles of the big bang theories in physics

By Katie Silver 8 April 2015 The recent film The Theory of Everything tells the story of Stephen Hawking, who managed to become a world-famous physicist despite being confined to a wheelchair by a degenerative disease.

It's mostly about his relationship with his ex-wife Jane, but it does find a bit of time to explain what Hawking has spent his career doing. He certainly didn't lack ambition. Hawking has been one of many physicists trying to come up with a "theory of everything", a single theory that will explain everything about our universe. He was following in the footsteps of Albert Einstein, who tried and failed to devise such a theory. Finding a theory of everything would be a staggering achievement, finally making sense of all the weird and wonderful things in our universe.

For decades, confident physicists have said that one is just around the corner. So are we really on the verge of understanding everything?

Einstein's Theory of General Relativity

View image of The universe contains billions of galaxies Credit: It would have to explain everything from the works of Shakespeare to the human brain and the forests and valleys of our natural world, says John Barrow of the University of Cambridge in the UK. That's because "the laws of nature are rather few, they're simple and symmetrical and there are only four fundamental forces.

But the rules underlying it all may be simple. In 1687, it seemed to many scientists that a theory of everything had been found.

  1. The higher one will gain about a billionth of a second every year, because spacetime is slightly less warped 30cm further from the centre of Earth's mass. As time passes, Gonzalez anticipates that more gravitational waves will be detected by LIGO and other upcoming instruments, such as the one planned by India.
  2. Each bubble then expanded into its own universe.
  3. The tug of gravity Two objects exert a force of attraction on one another known as "gravity.

Newton was walking in a garden when he saw an apple fall from a tree The English physicist Isaac Newton published a book in which he explained how objects move, and set out how gravity works.

The story goes that, at the age of 23, Newton was walking in a garden when he saw an apple fall from a tree. At the time, physicists knew that the Earth somehow pulled objects down by the force of gravity. Newton would take this idea further. View image of Our solar system not to scale Credit: All these objects, which seemed so different, turned out to obey the same laws.

In the same book, Newton set out three laws governing how objects move. Combined with the law of gravity, these laws explained how a ball moves when you throw it and why the Moon orbits the Earth.

For instance, gravity doesn't explain how small objects hold themselves together, as the force isn't strong enough. Also, while Newton could describe what was happening, he couldn't explain how it worked.

The theory was incomplete. Mercury wasn't playing ball But there was a bigger problem. While Newton's laws explained most of the common phenomena in the universe, in some cases objects broke his laws. These situations were rare, and generally involved extreme speeds or powerful gravity, but they were there. One such circumstance was the orbit of Mercury, the closest planet to the Sun.

As each planet orbits the Sun it also rotates.

Newton's laws could be used to calculate how they should rotate, but Mercury wasn't playing ball. Equally strangely, its orbit was off-centre. The evidence was clear.

The Forgotten Mystery of Inertia

Newton's universal law of gravitation wasn't universal, and wasn't a law. Over two centuries later, Albert Einstein came to the rescue with his theory of general relativity. Einstein's idea, which in 2015 celebrates its 100th anniversary, offered a much deeper understanding of gravity. Really heavy objects like planets, or really fast-moving ones, can distort space-time The core idea is that space and time, which seem like different things, are actually interwoven.

Space has its three dimensions: Then there is a fourth dimension, which we call time. All four are linked in a kind of giant cosmic sheet. If you've ever heard a character in a science fiction movie mention "the space-time continuum", this is what they're talking about. Einstein's big idea was that really heavy objects like planets, or really fast-moving ones, can distort space-time.

It's a bit like the taut fabric of a trampoline: Any other objects will then roll down the sheet towards the object. This, according to Einstein, is why gravity pulls objects towards each other. This is a deeply weird idea. But physicists are convinced that it is true.

For one thing, it explains the strange orbit of Mercury. View image of The Sun's huge mass affects Mercury's motion Credit: As the closest planet to the sun, Mercury experiences much bigger distortions than any of the other planets. The equations of general relativity describe how this warped space-time should affect Mercury's orbit, and predict the planet's position down to a tee.

But despite this success, general relativity isn't a theory of everything, any more than Newton's theories were. Just as Newton's theory didn't work for really massive objects, Einstein's didn't work on the very small. Once you start looking at tiny things like atoms, matter starts to behave very oddly indeed. View image of Atoms have a central nucleus orbited by electrons Credit: Coming from the Greek atomos meaning "indivisible", the atom by its very definition was not supposed to be able to be divided into smaller particles.

But in the 1870s, scientists found particles that were almost 2000 times lighter than atoms. Scientists have found ways to divide matter smaller and smaller By weighing light rays in a vacuum tube, they found extraordinarily light, negatively-charged particles.

General relativity: How Einstein

This was the first discovery of a subatomic particle: In the next half-century scientists discovered that the atom had a nucleus hub, which the electrons buzzed around. This hub — which was by far the heaviest part of the atom — was made up of two types of subatomic particles: But it didn't stop there.

  • That's why some metals are attracted to magnets;
  • But it also has a host of problems;
  • View image of The Sun's huge mass affects Mercury's motion Credit;
  • To this day, we do not truly understand how the distant universe gives gyroscopes their marching orders.

Since this time, scientists have found ways to divide matter smaller and smaller, continuing to redefine our notion of fundamental particles. By the 1960s, scientists had found dozens of elementary particles, drawing up a long list known as the particle zoo.

As we understand it today, of the three components of an atom, electrons are the only fundamental particles. Neutrons and protons can be divided further into teeny, tiny particles called "quarks". Einstein never really believed in quantum theory These subatomic particles were governed by an entirely different set of laws than those governing big objects like trees or planets. And these new laws — which were far less predictable - threw a spanner in the works.

In quantum physics, particles don't have defined locations: All we can say is that each particle has a certain probability of being in each location. This means the world is a fundamentally uncertain place. This may all seem very unfathomable and far-out.

All we can say is, it's not just you that feels that way. The physicist Richard Feynman, an expert on the quantum, once said: View image of General relativity works for big things like stars Credit: Quantum physics has explained the structure and behaviour of atoms, including why some of them are radioactive.

It also underlies all modern electronics. You could not read this article without it. Meanwhile general relativity was used to predict the existence of black holes. These are stars so massive that they have collapsed in on themselves.

No Big Bang? Quantum equation predicts universe has no beginning

Their gravitational attraction is so powerful that nothing — not even light — can escape from it. View image of General relativity suggested that black holes exist Credit: General relativity says that objects' behaviours can be predicted exactly, whereas quantum mechanics says all you can know is the probability that they will do something. That means there are some things physicists still can't describe.

Black holes are a particular problem.

Beyond the Big Bang: Sir Isaac Newton's Law of Gravity

They are massive so general relativity applies, but they are also small so quantum mechanics applies too. Unless you're close to a black hole, this incompatibility doesn't affect your day-to-day life.

But it has perplexed physicists for most of the last century. It's this incompatibility that has driven the quest for a theory of everything. View image of Einstein wanted to make sense of the universe Credit: Never a fan of the randomness of quantum mechanics, he wanted to create a theory that would bring together gravity and the rest of physics, with all the quantum weirdness as a secondary consequence.

Einstein spent 30 years on a fruitless quest His major challenge was to make gravity work with electromagnetism. In the 1800s, physicists had worked out that electrically-charged particles could be attracted or repelled by each other. That's why some metals are attracted to magnets. This meant there were two kinds of force that objects could exert on each other: Einstein wanted to bring the two forces together into a "unified field theory".

To do this, he extended his space-time to five dimensions.

  1. The theories are really difficult to test, largely because the maths is so fiendish.
  2. In quantum physics, particles don't have defined locations. The force tugging between two bodies depends on how massive each one is and how far apart the two lie.
  3. The scientists propose that this fluid might be composed of gravitons—hypothetical massless particles that mediate the force of gravity. It introduced a new framework for all of physics and proposed new concepts of space and time.

As well as the three of space and one of time, he added a fifth dimension that was so small and curled up we couldn't see it. This didn't work out, and Einstein spent 30 years on a fruitless quest. He died in 1955, his unified field theory still undiscovered.