Albert Einstein changed the world forever 100 years ago this month by publishing his theory of general relativity.
Relativity is now a centrepiece of modern physics, the reason GPS satellites and mobile internet exist, and why Einstein is easily the most famous scientist in history.
But a legendary status doesn’t mean you’re infallible. Einstein made plenty of errors and oversights, and sometimes, he was flat out wrong.
Here are five of Einstein’s biggest mistakes explained.
But in order to get the maths right, Einstein had to create a new constant number (an unchanging value, like 'pi' or 'e') and stick it inside his general relativity equations to balance them.
He called it the 'cosmological constant,' and it helped the equations account for the unchanging nature of the universe.
But not long after Einstein published his equations, physicists discovered that the universe wasn't constant, but actually expanding all around us at a blistering speed. Oops.
Scientists now see the cosmological constant as representative of a mysterious force called dark energy, which is causing the universe to expand at a faster and faster clip.
Fields of gravity around objects warp light waves as they pass through, like a huge cluster of galaxies.
The bigger the object, the more it will bend light rays around it. The effect is called gravitational lensing. It's the best way to measure the mass of huge, distant objects. It also magnifies images of really distant objects so that astronomers can observe them from Earth.
But Einstein thought gravitational lensing would be too small to see. He dismissed the idea as mostly useless, and he didn't bother publishing his findings until a colleague urged him.
It was a serious misjudgment on Einstein's part to dismiss the idea, at least initially, considering how important the technique is today.
So Einstein rejected gravitational waves (even though his own theory predicted they exist!). He almost published a paper containing that huge error.
But even though the maths suggests gravitational waves are real, we still haven't directly observed them.
A huge manhunt is underway for the elusive waves. There are several gravity wave detectors in the US and abroad, and teams of physicists are hot on the trail.
4. Einstein ran into a similar problem with black holes: His theories predicted their existence, but he couldn't make sense of them.
We now have plenty of evidence that black holes not only exist, but some grow to millions of times the sun's mass, including one at the center of the Milky Way.
5. Einstein's later ideas were critical in the development of quantum mechanics -- a branch of physics that studies the bizarre properties of tiny subatomic particles.
In fact, the research that earned him the Nobel Prize in 1921 (the photoelectric effect) was hugely instrumental in the development of quantum mechanics.
Quantum mechanic's bizarre properties suggest particles can be in two states at the same time, and can send information to one another faster than the speed of light.
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