We tell time by measuring a repeating pattern. The earth spins — causing it to be light and dark, which we translate as a day. Pendulums swing back and forth, which we translate as a second. Scientists would call things-with-repeating-patterns oscillators. However, there is a problem.

Researchers have found that the earth speeds up and slows down in unpredictable ways. So, the earth is not a good way to measure the passing of time. The earth is a bad clock.

This is unfortunate, since we need precise clocks for many of the technologies we use,  like GPS. So we need a better clock–a more precise clock, a clock that is stable for a long time.

To make a better clock, it needs three parts: An oscillator to produce a repeating pattern; a counter to measure how often the pattern occurs. And, a part to make sure that the oscillator is creating this pattern correctly—which is called a discriminator.

Deep in a precise clock, or an atomic clock, is an oscillator. In this case, it is a quartz gem that is vibrating—the quartz acts like a piece of jello that wiggles when hit. And, those wiggles are counted to tell time.

To make sure that the quartz is wiggling correctly, atoms are used to check it. Cesium atoms

How?

Well, inside the atoms are electrons. And, electrons live at different levels from the center. Electrons can move up and down these levels, like a ladder, when they get zapped with energy. However, the electrons can’t keep that energy, so they give back a precise amount of energy when they return to their original level. It ends up that that energy given back has a precise oscillation to it. This is compared to the wiggles made by the quartz to see if the quartz is correct.

Sure, there are lots of steps, but it is worth it, since atoms are very precise. They lose their precision every 1.4 million years.

So it seems that atoms take a licking, and this keeps clocks ticking.

 

Foams are everywhere from the cosmos to your cappuccino.

Bubbles and foams are everywhere—from soap bubbles to sponges. Foams are mostly air, about 90 percent air, and when air is mixed with liquid to form a foam, together they act like a solid. Try it out for yourself. Push on some bubbles next time you are washing the dishes, they will move with force, but not on their own like a liquid would.

Here is a little bubble secret. Bubbles can help you from spilling your drink. Recently researchers have found that beverages that have 5 layers of bubbles on the top will be less likely to spill than a liquid without bubbles. This means that a latte will not spill when you walk, while hot coffee without bubbles will spill. Ouch. If you are commuting and want coffee, order a coffee with a bit of foam on the top and spare your epidermis.

So what are the bubbles doing? Well, the bubbles push against each other and the friction between the bubbles eats up the energy of the sloshing. The liquid with bubbles on top will not come out of the cup when you are walking. So, a soda with lots of bubbles does a better job of not spilling than a flat soda.

See for yourself in this short video:

http://gfm.aps.org/meetings/dfd-2014/5416599269702d585c690100

Ice Cream and Pudding and Bread, Oh My

The world is full of solid foams too, that is, foams that combine air with a solid. There are many that are quite yummy. Ice cream, pudding, and bread, are all solid foams. The bubbles give these foods mouth-feel, which is what makes them so pleasing.

But, there are more serious uses of foams. Scientists wanted to catch a bit of comet dust, which holds secrets about the formation of our solar system. It ends up that comets fly really fast (like 40 times a bullet) and catching dust particles in a cup would not work, because both the cup and the dust particle would be destroyed. What was needed was a way to capture comet dust that would not hurt the dust. So, scientists use a special foam, called an aerogel, which is 99.8 percent air with the rest being glass. As the particle enters the aerogel, small glass fibers are broken, which slow down the comet particle without hurting it. From these particles we can learn more about comets and our solar system.

What will bubble up from these findings is uncertain, what is clear however is that the uses of bubbles and foams are unlimited and even cosmic.

References:

Universal Foam 2.0 by Sidney Perkowitz (Affiliate Link)