The Light Speed is 300 million meters per second, or 299,792,458 to be more exact. With that speed, light is able to encircle Earth 7.5 times in just one second. But we humans here back on Earth don’t really see that as being slow, right? I mean, come on, when travelling down the highway at 120 kilometres per hour, 300,000 km per second doesn’t sound that slow. But it actually is. It is if we are to compare it to the size of the Universe.
Let’s put things another way, shall we? The universe as a whole may be infinite for all we know, but the part that we can see, the observable universe, is huge in its own right. It’s impossible to even imagine the distances involved, but to give you a number, it’s 93 billion light-years across. And you know it must be humongous as long as it’s in the billions, and it has light-years in it. The universe is only 14 billion years old, so that should tell you something. In other words. it would take light travelling from one side of the observable universe to the other 93 billion years to get there. And this excludes the fact that space is expanding at an ever increasing rate.
But to make things more relatable, if we were to scale down the observable universe to the size of the Earth, our own Milky Way galaxy would be the size of three houses apart in a neighbourhood. But travelling at the speed of light, going from one side of the galaxy to the other, it would take roughly 100,000 years. Imagine going by spaceship and wanting to go to the far end of the Milky Way. It will never happen in your lifetime or your children’s lifetime, or your children’s children’s lifetime.
For those of us who don’t know, it takes light travelling from the Sun to the Earth, eight minutes to get here. To reach Jupiter, it takes it 45 minutes, and to reach Pluto, roughly 5 hours. Now, when we look at the stars at night, we should realise that what we’re seeing if hundreds of year old light travelling through space to reach us. It is important to note that with the naked eye, we can only see stars that are only around 100 light years away, or so.
So, with all of this being said, why is light speed so slow?
And this answer might come as a surprise or not, but we don’t know – it’s just the way it is; just like gravity or other physical forces in the universe. We know they exist, but we don’t know why they exist the way they do.
Now, if we were to make a thought experiment and look at this in more detail, we could theoretically speed up light by a factor of 1,000. If this were the case, a spaceship going at light speed would cross the Milky Way in just 100 years and would reach the nearest solar system, Alpha Centaury in just 2 days. Computers and networks would also run faster than they do now and we would have a greater chance of receiving some sort of signal from extraterrestrials.
On the downside, however, if light speed was 1,000 times faster, then the Sun and all other stars for that matter, would be a million times hotter. So, for better or worse, it’s good that the light speed is as slow as it is.