EFFECTS OF GRAVITY ON HEIGHT
- By Irene, 19th April 2020
When I first heard this idea from Prax I got very excited: measuring the changes in height during the day due to gravity… such a non-sense experiment! What I didn´t know is that he really meant it: he was convinced that the gravity can swing our heights a few centimetres up and down every day. A few centimetres!
So the idea is simple: when you are standing, the gravity will exert more pressure in your longitudinal axis and you will shorten; on the contrary, when you are lying the gravity force will be perpendicular to you so you will elongate. Here is a simple depiction:
And I repeat: we are not talking about small changes in the microscale, we are talking about various cm difference.
I had to prove him wrong, so I accepted the challenge.
The height will decrease throughout the day more than 1 cm (due to the effect of gravity).
Note that I wrote “due to the effect of gravity” into parenthesis because we can´t determine the actual cause of the height reduction. We still don´t have zero-gravity rooms.
- Prax´s prediction: yes, of course, height decreases with gravity a few cm every day and increases during the night while you sleep. Didn´t you know it?
- Irene´s prediction: bullshit.
Two height measurements we taken for each day: 1 before sleeping and 1 after waking up. Each measurement was repeated two to three times to have an estimation of the error. The experiment was conducted for 4 days.
The height measurement system consisted of the following items:
- A wall
- Measuring tape
- Tape (to tape the tape)
- The lid of a box
- A clipboard with a painted owl
- Pen and paper
- Determination to wake up together at the same time every day
The measuring method can be seen in the following images:
So this is the raw data. We took 2 replicate measurements at 10:00 and at 00:00 for the following 4 days:
We calculated the mean and standard deviation for each of us at morning and night-time. Note that our awesome height measuring system had a very low error! 😎
Then, to see if the differences between morning height and night height were statistically significant, we did a t-test with 95% confidence interval.
Result… both were strongly significant!
Our heights decreased around 2 cm during the day. Point for Prax 🙈
So, even though we can´t still prove that the height shrinking is due to gravity (other possibilities are a worsening of flexibility during the day, or the polishing of the feet while we walk which magically reverses during sleeping); the fact is that people are shorter in the night than in the morning (or at least us). How fast is this shortening we don´t know… we were not intelligent enough to take several measurements per day to see if the shortening is gradual or sharp, so it´s still possible that the height increases by 10cm in mid-day and decreases by 12cm later on… you never know. We will unveil this and other problems soon and update our data. If you have any suggestions, just leave a comment!