What will the universe be like in 100 trillion years?
In 100 trillion years, galaxies will contain fascinating astronomical objects that we cannot encounter now, and overall, the Universe will be a different and relatively unfamiliar place. We…
Why is the speed of light so small relative to the size of the universe?
That’s a good question since so many people imagine that the speed of light is very fast, when it is extremely, extremely slow in an astronomical context. And…
How can Voyager send a signal strong enough for us to receive, in spite of its enormous distance from us? And how can it have the power to do so more than 20 years after its launch?
It’s better to reverse the question and ask not how Voyager can send a signal strong enough, but how Earth can receive a signal so weak. The signal…
What would happen if a Jupiter-sized iron planet hit the Sun at 100 kilometers per second?
First of all it could NOT hit the sun at 100 km/s – the MINIMUM speed at which it could hit the sun would be 617 km/s. If…
Why are the B-52’s engines mounted in pairs?
In 1955, they could build an engine of that size. They worked, they worked well. Being a military craft, they might get shot at, might have to fly…
Why did NASA spend millions developing a pen that would work in space when a pencil is just as good?
They didn’t. The “million-dollar space pen” story is an urban legend that just refuses to die. Pencils aren’t “just as good” in zero-G; in fact, they’re absolutely terrible….
If the universe is so big, why haven’t we encountered an advanced alien civilization yet?
Look at it like this. If there were intelligent life out there, how would they know about us? The only way is by monitoring radio transmissions. The first…
Is it true that the earth is round?
In 1989 I saw a slightly different proof that our earth is round 🙂 There are many ways to prove that our earth is round. But in 1989…
If you take a gallon of water from the deepest ocean and bring it up to the surface in a sealed container, will the pressure break the container as it is risen up into the surface?
At the depth of the typical ocean floor — about 3km — water is compressed to 98.2% of its sea-level volume. The Mariana Trench is just over 11km…
If I have a circular disc of radius 300,000 km and made it rotate with 1 rad/s, wouldn’t a particle on the edge of that circular disc exceed the speed of light?
No. This is a very common thought-experiment – called the Ehrenfest paradox – and like most paradoxes – it isn’t a paradox at all. The problem is that you’re imagining…