Why can't I get bigger?

Greater in the morning than in the evening

What a strange question? One would like to spontaneously say "No, of course not!" answer.
But, give it a try:

You take:

  • A wall
  • A book
  • A pen
  • A measuring tape

And of course you still need someone to help you measure and who has a lot of time. In the morning right after getting up you have to take the first measurement. So, put it against the wall, turn the book upside down and draw a line. And you do the same again in the evening.

You will find that there is one to two centimeters between morning and evening. Where did you just lose it? "To blame" for the loss of size is gravity and your spine. Because there are not only bones, but also those Band washers. They are very elastic and ensure the mobility of our body. If we didn't have any intervertebral discs, we would be pretty stiff. We couldn't bend or twist the upper body.

Imagine the spine as a toy train: between the individual wagons there are small sponges that enable and cushion movements. The intervertebral discs soak up fluid overnight. During the day - when sitting, running, walking, playing, carrying heavy things and simply by gravity and your own body weight - they release the liquid again. This compresses the spine - and becomes shorter! And you can read that off the tape measure at the end of a long day.

By the way: That doesn't happen in space. Because there is no gravity that could press on the spine. In a spaceship you are guaranteed to stay the same size!