-- particles


- 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:

Measuring System


So this is the raw data. We took 2 replicate measurements at 10:00 and at 00:00 for the following 4 days:

Raw Data

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! 😎

Mean and Standard Deviation

Then, to see if the differences between morning height and night height were statistically significant, we did a t-test with 95% confidence interval.

T-test for Irene
T-test for Prax

Result… both were strongly significant!

Our heights decreased around 2 cm during the day. Point for Prax 🙈

Final Results


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!

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@prax99 @miausola


Complex_exam.com - April 27, 2020, 2:30 p.m.
One thing proven right: website's name.
Bata Ballu - April 26, 2020, 7:55 p.m.
The name of the website actually suffices for the experiment...
Eva - April 24, 2020, 9:22 p.m.
Esto de tener mucho tiempo libre mola, eh? Se agudiza el ingenio... De los que lo tienen, claro. Enhorabuena a los dos!
Anonymous - April 23, 2020, 8:48 a.m.
oooooh! No wonder I play basketball better during the day than the evening!
Anonymous - April 22, 2020, 8:30 a.m.
Anonymous - April 22, 2020, 8:09 a.m.
Nice content!
Anonymous - April 21, 2020, 9:54 a.m.
Maal 🔥
Javier - April 21, 2020, 9:54 a.m.
I really feel the effects from gravity each day, not by measuring but drawing a line in the mirror the first minute in the morning just at the same level than my eyes. At the end of the day will demonstrate that my eyes will be underneath the line. Very good and nice theory and experiments, congratulations
Anonymous - April 21, 2020, 9:54 a.m.
Anonymous - April 21, 2020, 9:54 a.m.
Hahaha, cool!
Harry Potter - April 21, 2020, 1:24 a.m.
Cool experiment. The astronauts in space also proved the theory though.
AwesomeKing99 - April 21, 2020, 1:24 a.m.
Pretty elegant and really nice to read. Looking forward for more posts!
Antonia - April 21, 2020, 1:24 a.m.
suggestion: extend the period under analysis, divide the day when you are all day seating and other where you make sport, try to stay 1 or 2 day in lying position also during the day and measure in the evening and 1 or 2 days all the time standing and measure in the evening to see if it is because of the gravity or for the flexibility of the body. Good luck :-)
Anonymous - April 21, 2020, 1:24 a.m.
/me slow claps
Anonymous - April 21, 2020, 1:24 a.m.
Awesome!! Hahaha

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