When the Golden Gate Bridge went up, it was the longest suspended bridge span in the world – cables hold up the roadway between two towers, with no intermediate supports. And the setting had a number of inherent challenges. It cost about US$37 million at the time; building the same structure today would cost about a billion dollars. So how has the design held up over the past 80 years – and would we do things differently if we were starting from scratch today?

During the 19th and 20th centuries, physicists began to probe deep into the nature of matter and energy. In so doing, they quickly realized that the rules which govern them become increasingly blurry the deeper one goes. Whereas the predominant theory used to be that all matter was made up of indivisible atoms, scientists began to realize that atoms are themselves composed of even smaller particles.

Gravity is a pretty awesome fundamental force. If it wasn’t for the Earth’s comfortable 1 g, which causes objects to fall towards the Earth at a speed of 9.8 m/s², we’d all float off into space. And without it, all us terrestrial species would slowly wither and die as our muscles degenerated, our bones became brittle and weak, and our organs ceased to function properly.

Everyone knows just how fun magnets can be. As a child, who among us didn’t love to see if we could make our silverware stick together? And how about those little magnetic rocks that we could arrange to form just about any shape because they stuck together? Well, magnetism is not just an endless source of fun or good for scientific experiments; it’s also one of basic physical laws upon which the universe is based.

How short is an “instant”? Is it a second? A tenth of a second? A microsecond? You might think all of these qualify. What about 100 years? That certainly doesn’t seem like an instant, and to a human being, it isn’t, since we’d be lucky to have a lifespan that long. But to a giant sequoia, say, 100 years is no big deal. And in geological terms it’s practically nothing.

Research is an unpredictable process. Sometimes you end up making a really cool discovery that you didn’t see coming. I recently uncovered a fundamental property of lightsabers (that’s right – the awesome weapons from Star Wars) while doing my regular plasma physics research. I found that, while it is in theory possible to build a lightsaber, it’s likely it would be the most dangerous weapon ever created – both for the perpetrator and the victim.

Every now and again, we all indulge in dreams about travelling in time. Wouldn’t it be wonderful to return to that specific point in the past to change a bad decision or relive an experience – those halcyon days of childhood, that night you won an Oscar – or to zip ahead to see how things turn out in the far future.

Imagine time running backwards. People would grow younger instead of older and, after a long life of gradual rejuvenation – unlearning everything they know – they would end as a twinkle in their parents' eyes. That’s time as represented in a novel by science fiction writer Philip K Dick but, surprisingly, time’s direction is also an issue that cosmologists are grappling with.

Our understanding of gravity has gone through a few permutations, from Newton’s equations through to Einstein’s general relativity. With the discovery of gravitational waves, we look back on how our grasp of gravity has evolved over the centuries.