Dear Vishi, is there a time machine?

Did you remember we watched The Time Machine movie together? The protagonist loses his fiancée when a mugger kills her. He then builds a time machine to travel back in time to save her. Of course multiple movies have been made romanticizing the concept of time machine.

I am not sure if the laws of physics allow time travel. There's no scientific consensus if time travel is possible in theory. Even if it was possible in theory, it might take aeons before humans could master time. However there's one time machine you see everyday.

Have you looked at the moon today?

Moon

If I told you that sky is a time machine you might call me bonkers. However sky does mirrors the past. Moonlight takes 1.26 seconds to reach earth. So you are looking at moon 1.26 seconds in the past. This might not be a significant delay. However for other celestial objects the delay is significant. Venus, for instance, is the brightest planet you can see from earth. On some occassion, Venus can be visible on a broad daylight. It takes 3 minutes from a light to travel from Venus to Earth. Venus is so bright it is often mistook for an alien spaceship.

What about the sun, the gigantic ball of gas? It takes 8 minutes for light to travel from sun to earth. If the sun is diabolically annihilated, we wouldn't realize its repercussions for atleast 8 minutes. Sun is dwelling in the 8 minutes past.

Alpha Centauri is the closest star to earth. It's 4.37 light years away. 1 light year is the distance light travels in vacuum in 1 year. So it would take approx 4 years for light to travel from Alpha Centauri to us. If Alpha Centauri is annihilated today, we still will be able to see it for next 4 years. Do you wonder how many stars in the sky are already dead?

Coconut Water

Today I had coconut water. I drank it from the source itself, the coconut. It saves me from the added sugar & preservative from the packaged coconut bottle available in the shopping mall.

Coconut Water

In India, it's easy to find patchy shops on the road sideways selling fresh coconut water. However in the US, I couldn't find any fresh coconut water. Most of the retail sector is very organized in the US. I only relied upon packaged coconut water.

Health

Treadmill

Below is the snapshot of my treadmill activity. I still need to improve my vital capacity & stamina.

Code

Today I solved a problem on Binary Tree, All Nodes Distance K in Binary Tree. I've created a repository in Github to track my progress on problem solving.

I would recommend you to create a Github repository to keep track your progress of SQL problems. This will help you to stay motivated.