Archives of Ask A Scientist!
About "Ask A Scientist!"
On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.
Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.
So, even if all the babies born did add to the mass of the earth, it would hardly be noticeable. But the population changing doesn't change the mass of the Earth. Before a baby is born, it grows inside its mother. When someone grows, baby or otherwise, they're not adding to the mass of the planet; rather,they're converting other mass into them. In some sense, you really are what you eat. If you eat a hamburger for instance, your body breaks that food down into molecules and atoms, incorporates what it can use into your body, and passes what it can't use out as waste. You're just taking matter from something else and incorporating it into yourself. The famous chemist Antoine Laurent Lavoisier did a series of careful experiments back in the 1780's that showed mass was not created or destroyed in chemical reactions. By performing chemical reactions in sealed containers, he showed that the total mass is conserved. If you burn something like a piece of wood, the ash left doesn't have the same mass as the log, some of the mass of the log has escaped in the smoke. However, if you could keep track of where all the atoms from the log went up in smoke, you'd be able to tell that the total mass of the log and the air involved in burning it hadn't changed when it was smoke and ash afterwards.
Incorporating food into your body is a much more complicated chemical reaction, but also doesn't change the amount of mass on Earth. In the case of an unborn baby, most of the digesting is done by the mother, but the baby still converts the matter she passes to it into baby.
There are ways that the mass of the Earth can change. For instance, the lunar rover was left on the Moon by the Apollo astronauts, so that mass is no longer part of the Earth. Meteorites that crash into our planet, or even burn up in our atmosphere, can contribute some small mass to the planet. One of the most famous equations in physics, E=mc^2, actually tells us another way for total mass to change. Albert Einstein put forth the idea that matter and energy are just different forms of the same thing. Matter can be changed to energy, and vice versa. It doesn't happen much on Earth, but the massive amount of energy coming out of our Sun actually represents a gradual decrease in the Sun's mass. But that's a subject for another "Ask a Scientist."
- Why do solar cells produce more electricity in low temperatures?
- If a person stands on a circular rotating stand, facing away from the centre with arms outstretched holding a spinning bicycle wheel and tilts the wheel to once side this causes the stand they are standing on to rotate. My questions are: Why is this? Does it make a difference which way the bicycle wheel is spinning? Will the bicycle wheel's momentum be effected by the spin of the stand the person is stood on? For the strongest anti-clockwise pull on the stand should the wheel be angled by raising the right hand and lowering the left(tilting), or pushing forward the right hand and drawing back the left (turning).
- What happens at the edge of a diamond? How does the carbon end?
- Why is plasma classified as a phase? What is its chemical make-up? How was it discovered?
- How are crystals formed?
- How do lasers in machines work?
- Why does the light from a sodium lamp appear orange?
- What are hydrothermal vents?
- If the electrons are attracted to the protons, why don't they come crashing into the nucleus?
- How are dryer sheets manufactured?