10 Famous Thought Experiments That Just Boggle Your Mind Part 6

Read Part 5: The Ship of Theseus

5. Galileo's Gravity Experiment

In order to refute Aristotle’s claim that the speed of a falling object is dictated by its mass, Galileo devised a simple thought experiment:

According to Aristotelian logic, if a light object and a heavy object were tied together and dropped off a tower, then the heavier object would fall faster, and the rope between the two would become taut. This would allow the lighter object to create drag and slow the heavy one down. But Galileo reasoned that once this occurs, the weight of the two objects together should be heavier than the weight of either one by itself, therefore making the system as a whole fall faster. This contradiction proved that Aristotle’s hypothesis was wrong.

One of the most famous stories about Galileo is that he once dropped two metal balls off the Leaning Tower of Pisa to prove that heavier objects do not fall faster than lighter ones. In actuality, this story is probably just a legend. However an astronaut did perform this famous Galileo test with a hammer and a feather in vacuum with low gravity on the surface of the moon (see video below).

So what can I learn from this thought experiment? As a Computer Science researcher, many times it is easier for me to just sit down and code up experiments. But sometimes it might be a good idea to stand up and then write down the math formulations on the whiteboard. Simplifying the math calculations or jog down some proofs can actually dramatically reduce the amount of coding I have to do and also improve the performance of my algorithms. Of course, if I could do all these in my head it would be wonderful, but I am no Galileo, and I also have severe short-term memory deficit -- a strong sign and that I am almost ready to graduate!

Read part 7: Monkeys and Typewriters



Video of the Day:

Air Swimmers -- a fun "robot" toy for parties! You can get them here.

BTW: The easiest way to remember my blog address is http://lanny.lannyland.com

Robot of the Day: Microswimmer Robot Taking Pictures of Your Intestines

This is a robot I read about recently, a robot the size of a pill that can swim inside your body powered by external MRI machine's magnetic fields with the task of taking pictures of your intestines.

Credit: Tel Aviv University and Brigham & Women's Hospital

The robot was developed by scientists at Tel Aviv University in Israel and Brigham & Woman's Hospital in Boston and introduced in a recent paper published in Biomedical Microdevices. Although still in the early testing stage in a water tank, the tiny robot seems to maneuver well with its 20mm x 5mm tail. The eventual objective of robot is to enable doctors to see the inside of a patient's intestines and detect early stages of gastrointestinal cancer.

Presently doctors can already have patients swallow a pill-sized camera. Pictures are taken every half second or so until the camera is passed. However, doctors have no control of the camera's movement when they wanted pictures of specific part of the body. One challenge with the robot idea is how to power the robot because embedding large power supplies would increase the size of the robot and cause other problems. The beauty of the proposed solution is that it uses magnetic field to control the movement of the robot via the little copper and polymer tail. And since MRI machines are already a common device in hospitals, they can become very handy.

I remember seeing a video of how live bacterias can be controlled by magnetic fields to push around a "nano-robot" in a Discovery Channel documentary. In this case, the magnetic field controls the robot directly which is probably more predictable than trying to control bacterias.

Some people even suggest that we can leave such robots inside us permanently like parasites. Now imagine having a bunch of these things inside your body, constantly posting images or videos online of your internal like those live web cams.... Now you not only have no privacy outside of your body, you don't even have privacy inside your body.... Well, but if lives can be saved, I guess it's okay.

To read more about this, click here.





The good news: the robot is reusable!
The bad news: the robot is reusable!