What would it take to make contact?

The vast volume of the universe makes it very difficult to achieve interstellar travel, receive signals, or communicate with any potential far-off lifeforms (at least according to the laws of physics as we know them).

Speeds are limited to the speed of light, which is around 300,000 km per second. It’s pretty fast. But even at that speed it would take a signal roughly four years to travel between Earth and the nearest star in our galaxy, which is four light years away.

But Einstein’s theory of special relativity tells us that, in practice, the speed of a physical object such as a spacecraft will be slower than the speed of light.

Also, thanks to the inverse square law of radiation, signals get weaker in proportion to the square of the distance they have travelled. Over interstellar distances, that’s a killer.

So for planets hundreds or thousands of light years away, travel times are likely in the many thousands of years. And any signals originating from civilisations on those planets are incredibly weak and difficult to detect.

Cover ups?

Could it be aliens have crashed on Earth and the US government is just covering it up, as Republican Congressman Tim Burchett claimed in his reaction to the hearing?

For airlines belonging to the International Air Transport Association, the chance of plane crash is about one in a million. That begs the question: do we think an alien spacecraft that can travel for thousands of years, across interstellar distances, is more robust and better designed than our planes?

Let’s say it’s a hundred times better. Which means the chance of a crash is one in a hundred million. So to end up with alien wreckage stashed away at Area 51, we would need one hundred million visits from alien spacecraft. That would be 2,739 visits from aliens per day, every day, for the past 100 years!

So, where are they? The near-Earth environment should be constantly buzzing with aliens.

With radars constantly scanning space, billions of mobile phone cameras, and hundreds of thousands of amateur astronomers photographing the sky (as well as professional astronomers with powerful telescopes), there should be a lot of really good evidence in the hands of the general public and scientists – not just governments.