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.
What is happening at the molecular scale to give rise to the unusual properties of a hydrogel? Gelatin comes from the protein collagen, the main protein in connective tissues such as bones and tendons. When the gelatin is dissolved in hot water, the long polymer chains can move freely in solution. As the solution cools, the motion of the chains also slows down, allowing some chains to encounter each other and become entangled. As the degree of entanglement increases, the liquid is trapped and immobilized. The result is a material that behaves somewhat like a solid and somewhat like a liquid. In the case of the chicken stock, as the carcass is boiled, collagen protein chains are leached out of the skin and bones. Gelation is sometimes reversible, as in the case of Jell-OŽ and chicken soup, which means that as the temperature rises, the chains disentangle and the gel melts.
In addition to gelatin, there are a number of other natural and synthetic polymers that can form gels. For example, there are several vegetarian, edible hydrogels that are made from agar, alginate, and carrageen, which are all polysaccharides (polymers chains made from sugars) that are extracted from seaweeds. Many cutting-edge chefs incorporate gels into their dishes by taking advantage of the science of gels to create unique tastes and textures. For example, by choosing a gel with a melting point near that of body temperature, they make small capsules that melt in the mouth, releasing flavor. For more information on gelatin and other food-related hydrogels, I recommend the book "On Food and Cooking" by Harold McGee.
- Why is it that when I look at one side of the spoon I see my reflection right side up, and when I turn the spoon over I see my reflection upside down?
- I am currently studying electronics and how they work together to perform work. But I seem to get confused when the term "ground" is used. I understand that it is a "zero" reference point, and that it is a common return path for electrons to earth ground. I get stumped though when I see a schematic that has a ground attached to the negative end of a battery terminal in a dc circuit. Why don't the electrons just flow straight to ground? Then in an AC circuit schematic, I see a ground connection again connected to the negative side of a circuit. Can I assume that the ground is positively polarized which attracts the electrons?
- If light has no mass, why is it affected by gravity? I read that light can not escape a black hole because of the gravitational pull and that light from distant stars bends around our sun's gravitational field, making it appear that they are in a different direction from Earth than they actually are. I also read that light is massless, and that gravitational force is a function of mass. These seem inconsistent.
- Why is carbon the building block of matter?
- Can you find vitamins in the ground?
- How is the equation E=mc2 carried out physically?
- Why are the boiling points of metals with metallic bonds so varied?
- In an accelerator when an electron and positron collide, for a short time they form pure energy. Where does the energy come from if energy can't be created or destroyed and where does the matter go?
- How do you make a laser?
- Our textbook tells us the speed of the molecules that make up the air we breathe, but the speed it gives us is faster than the speed of sound. Why don't we hear sonic booms as when an airplane breaks the sound barrier? Are the particles just too small for us to hear the booms?