Wouldn’t it be great if scientists invented a device that enabled us to have a clear window into the past–so that we wouldn’t just have to read about the past in books?
Instead, with the new device–let’s call it a Time Window–we could actually see events occurring in the past in real time, with our own eyes?
That would be wicked awesome, wouldn’t it?
The exciting news is that scientists have invented this device!
That’s right! The Time Window is real!
What’s more, they invented it just over 400 years ago, so they’ve had the chance to mature the technology to the point that now it’s really, really good.
For comparison, imagine how good an iPhone would be today if Steve Jobs had invented the first one 400 years ago.
The only problem is that they missed a great marketing opportunity.
Instead of calling it the Time Window ™ they gave it a much more boring name . . . the telescope.
How the Time Window Works
The reason that the Time Window–er, telescope–lets us look into the past and see it with our own eyes is that it takes time for light to reach our eyes. The speed of light is not infinite.
Technically, this means that any time you see anything, you are technically witnessing something that happened in the past.
Since light travels so fast, however, if you see someone across the room pick up an iPhone, that happened only the tiniest fraction of a second ago. In fact, you started seeing it while it was still happening. That’s not long enough ago to make it an exciting glimpse into history.
But things get more interesting when you take a telescope at point it at something really distant.
For example, back in 1609, Galileo Galilei pointed his telescope at the planet Jove–er, Jupiter–and discovered that by it there were several moons.
Now the thing is, depending on where Earth and Jupiter are in their orbits, Jupiter is between 33 and 54 light minutes away from Earth.
Let’s just say it’s an average of 44 light minutes away for the sake of simplicity.
That means, it takes 44 minutes for the light from Jupiter to reach an astronomer on Earth.
So when Galileo looked at Jupiter through his telescopes and saw its moons, he was seeing where those moons were 44 minutes ago.
He was viewing actual history that occurred 44 minutes in the past!
Party Like It’s 1879!
The same thing keeps happening when you look further out.
Back in 2008, scientists used one of their spiffy modern telescopes to capture the light in this image . . .