Common Science Misconceptions

This is one of my posts in ReCom which I wish to share with everyone who studies science:

I found this fabulous website which pointed out a lot of common misconceptions in our textbooks. I would strongly recommend everyone who studies science to have a look. There are quite many commonly mistaken scientific facts, some of which were often included in our secondary, or even tertiary textbooks. Just sharing a few of them here:

1. Astronauts float in the space station not because there is zero gravity, but because they are free falling. The gravity in space is not zero. (Reference)

2. If we hang two balloons on each side of a beam balance, one of which filled and one of which empty, the side with the filled balloon will sag downward. It shows that air has weight. Wrong. The reason it sags downward is not because air has weight, but because of the different pressure in the two balloons. (Reference)

3. If we let sunlight goes through one prism, a band of light with the whole range of spectrum will be seen. If we let the spectrum of light goes through another identical prism, we will see white light coming out from the other end. - No, it's not the actual case. We won't get a white light using only two identical prisms. (Reference)

4. Infrared is the "heat radiation" while the other part of sunlight only contributes to the visible light but not heat. Wrong - if we measure the different parts of spectrum of the sunlight, we will find that the visible light contributes to heat as well. In fact, every one of us is emitting infrared and microwave at this very moment; but we don't emit visible light because we are simply not hot enough. (Reference)

5. Electrons flow at the speed of light - wrong. Electron actually moves very slowly, at the order of centimetres per minute. The thing that flows so fast and cause your light to snap on the moment you turn it on, is not electrons but the energy carried within the electrons. Think of what happens when we fill a pre-filled water hose with one drop of water at one end - a drop of water comes out from another end. Does it mean that that particular drop of water has travelled the length of the hose and come out at the other end? No. This is analogous to what happens in our conductors. (Reference)

6. The white "smoke" coming out from our piping hot coffee, the mist in a shower room, fog and cloud are not water vapour - they are fine liquid droplets. (Reference)

The things I listed above are among the inaccuracies or errors I learnt from the website. It's so enlightening, and I really hope that they include the facts from that site in our textbooks.