One of the most basic features of the universe, its size, is still an enigma. As we look up above, we can see lots of darkness peppered with stars. We know that it is big, but how big is it? Well, scientists don’t always agree. The trouble is that we can’t see that far.

How do we see the stars?

Though we might not be able to see any end to the universe, we can see lots of closer objects: like stars, planets, and asteroid belts. But, when you see the twinkle of a star, you are not really getting a “live” view. The star is so far away, that the twinkle that you are seeing may have happened years ago!

Light is really slow.

Here is what happens when a star twinkles: Deep out in space, the star decides to send out a flash of light. This star is 2 light-years away from earth. The light from this twinkle shoots out into space in all directions. The tiny light particles (called photons) headed in earth’s direction speed toward earth at the speed of light. But, this star is so far away from earth, it takes the photons of light 2 years to reach earth. After this 2 year journey, this photon reaches the eye of a curious star-gazer on earth enjoying the twinkling star.

We can only see anything once the light gets to earth

This presents a problem for astronomers trying to find the size of the universe: we can only see something in space once light from the object reaches earth. The twinkling star in the sky could explode, and we wouldn’t know about it for 2 years!

This is a picture of a star explosion, called a supernova.

The universe isn’t very old

Scientists currently estimate that the universe is about 14 billion (that’s a thousand thousand thousand) years old. This means that the first photons of light were first formed 14 billion years ago. Because light is so slow, some photons formed at the beginning of the universe are just reaching earth now.

Herein lies the problem: we can’t see anything further than 14 billion light-years away. Any further than that, and the light just hasn’t arrived to earth yet.

So how big is the universe?

This question is still open to debate. For the most part, your guess may be as good as most physicists’ guess.

What we do know is that the universe continues for at least 14 billion light-years in every direction around earth. Past that, we just can’t see anything yet. The furthest object we have seen is the Abell 1835 IR1916 galaxy, which is 13.2 billion light-years away.

What do you think?

Do you think the universe is infinite? Is our universe the only one? Leave your thoughts in a comment below.

( star photo credit: Zach Dischner; supernova photo credit: DJ Quietstorm)

So get rid of the carbon

The solution to global warming (at least the part that we contribute to) is to reduce the amount of carbon in the air. The thought is that, if you get rid of the CO2 in the air then less of the sun’s energy will be trapped in the earth’s atmosphere. When less energy is trapped, the globe doesn’t heat up as much. Pretty simple right?

Blame the fossils

Reducing the carbon in the atmosphere would be much easier if we didn’t rely so heavily on certain types of fuels called fossil fuels. Fossil fuels, such as coal, oil, and natural gas, are fuels which come from the ancient remains of dead plants, animals, and other organisms. Over millions of years, their remains were converted into fuels. These fuels lie buried underground, just waiting to be mined or drilled for our use.

And we do use them… 86% of our energy comes from fossil fuels. Energy from burning the fuels powers our homes and fuels our cars, among other things. The truth is that, as a society, we are addicted to energy; we can’t get enough. But all that energy comes at a price: burning fossil fuels releases carbon into the atmosphere.

More carbon = more warming= bad news for the environment.

Enter biofuels: they had so much potential

In response to this, many different ideas surfaced about how we can replace fossil fuels. One of the more widely implemented solutions to this was the biofuel movement. Biofuels are, by definition, fuels which are made from biological material such as corn or natural fats. You may have encountered automobiles designed to run on E85, which is a fuel made from corn ethanol.

The idea was this: plants are made of carbon. They get their carbon by taking it from the air. When you burn fuels made from plants, you are not adding “extra carbon” to the air; just returning what the plant took out of the air.

Sounds good, but it had some problems

The use of biofuels had two major issues which got in the way of its use. The first issue was the “carbon costs” involved in producing the plants. When farmers grow the corn, they burn lots of fossil fuels to run the machinery used to care for and process the plant material.

The extra demand for corn had consequences on the economy as well. Because so many people wanted corn for biofuel production, the price of corn increased. This increased the prices of many different foods which rely on corn (chickens eat lots of corn).

The future is cellulose

Despite these setbacks, scientists are hard at work trying to overcome these drawbacks. One of the technologies in the works involves utilizing the cellulosic biomass of plant material. Cellulosic biomass is a very common carbon source: every plant has cellulose. It turns out that it is very difficult to digest into a usable form for biofuels (the common name for cellulose is “fiber,” we can’t digest it either).

To make the future even brighter, we don’t even have to use corn to get the cellulose: scientists are exploring the use of switchgrass, a plant which is very good at sequestering carbon out of the atmosphere. The catch right now is that this carbon is sequestered into cellulose: a currently unusable form.

In the future, we might be able to use this untapped resource of carbon to make biofuels. Scientists are currently working on engineering a microbe which can digest the cellulose, and they are getting very close to a viable alternative to fossil fuels. One of the last challenges is to make the process cheap enough to compete in the marketplace. These new technologies are a step in the right direction toward reducing our carbon emissions.

What do you think? Are biofuels the answer to global warming? Leave a comment below.

( themometer photo credit: Robbie1; corn photo credit: L. Bernhardt, Resident Loon)

Scientists were trying to culture human cells

Unbeknown to her, Henrietta’s physician had sent a sample of the cervical tumor to a colleague. At the time, scientists at Johns Hopkins Hospital were trying to establish a line of human cells which would grow in a dish. This was proving to be a big problem for the Johns Hopkins scientists, as human cells do not like to grow outside of the body.

Cancer cells grow out of control

When they put a piece of Henrietta’s tumor tissue in culture, it grew extremely well: much better than all their previous failed attempts. Unlike normal cells, cancer is used to growing where it doesn’t belong. The same thing that made the cancer so aggressive to Henrietta made it a perfect candidate for growing in culture.

The HeLa cell line: a staple for medical researchers

The descendants of that tumor tissues are still alive today. Ask any biology undergraduate, and they will likely have heard the name of Henrietta Lacks. The cells are the most common cell line used in  research: they have been used to study AIDS, cancer, genetics, and have contributed to countless other medical breakthroughs.

Dividing HeLa cell culture under the electron microscope.

The ethics of taking this tissue without her knowledge are very questionable: is it right to use someone’s cells without their permission if it advances medical knowledge?

Henrietta Lacks is still alive

Though her body is no longer alive, the HeLa cells growing today in laboratories are Henrietta’s cells. And there are lots of these cells! More today than in Henrietta’s whole body when she died. She truly has been able to live on forever.

What do you think? Would you want to live on forever? Leave a comment below.

Why is a crayola “washable,” and a sharpie permanent? When you put the crayola through the wash, the water can dissolve the ink out of the shirt, but this doesn’t happen with sharpies. The answer has to do with the chemistry of the dyes.

Some love water, some fear it.

Water is a big part of our lives: it makes up a great proportion of the world we live in. Because of this, we think of most chemicals in two different categories. The ones who like water, hydrophillic (meaning water-loving) and hydrophobic (meaning water-fearing).

It gets worse. Its not enough that they either hate or love water, but the ones who hate water stick together and exclude the ones who love it. It turns out that it takes less energy for them to interact with their water-hating buddies than it would to try to mingle with the water-lovers.

These categories show up all the time in our lives, and we mostly don’t notice it. Take, for example a vinaigrette salad dressing:

Leave it in the refrigerator too long, and it will separate out into fractions. The water-hating hydrophobic oil floats up to the top of the bottle and sticks together. This leaves the water-loving hydrophillic vinegar by itself.

To clean, you must dissolve

The different dyes in different markers work just like the oil and vinegar in the vinaigrette. Crayola markers’ dye molecules are very hydrophillic. They love to hang out with water, and other water-lovers. When the dye is put onto a surface, it will stay there until it gets dissolved in something else. Because the dye loves water so much, you can just rinse it in water and it will dissolve away.

So when little Johnny decides that his shirt would look better in red, you can just throw the shirt in the wash. The water will dissolve away  the marker and it will go down the drain.

Despite how much scientist know about dissolving, we can’t solve the mysteries of the dissolving card:

httpv://www.youtube.com/watch?v=yFmBwffoZJI

Yes, the video is a bit off topic. But still very cool.

( Kid Drawing photo credit: juhansonin;vinaigrette photo credit: surekat)

But what is it exactly that makes butter solid? And why is vegetable oil liquid at the same temperature? They are both essentially the same thing: fats. What makes them different? The answer has to do with their chemistry.

Fats are long strings of carbon and hydrogen

Fats, like all the other foods that we eat, are just chemicals. Yummy, greasy, chemicals, but they obey the same laws of chemistry as everything else in the world.

Fats (or lipids, as they are called by nutritionists) are mostly made up of a chemical group called hydrocarbons. Its hard to think about, but the fat that you eat is made up of tiny little strings of carbon and hydrogen. The picture below is of a typical hydrocarbon: the black is carbon, and the white is hydrogen.

This is a picture of a typical saturated hydrocarbon.

What you should notice about this picture is that there is hydrogen is all over the carbons. There is no where else that you could stick a hydrogen on this molecule. Chemists would say that this is saturated with hydrogens. It turns out that, this is why the fat is a straight stick. The carbon can’t bend because the hydrogen gets in its way.

Unsaturated fats have less hydrogen, so they bend

Some organisms (especially plants) like to make lipids without all the hydrogens in them. These lipids are called unsaturated fats because they are not saturated with hydrogen. Because of this, the carbon chain bends, putting a kink or two in the shape.

This fat molecule has some kinks in it. The loss of hydrogens puts double bonds in the carbon. Double bonds have a different shape.

This is what you see in the fat content on the back of food nutrition labels: Saturated fats are straight. Mono-unsaturated fats have one kink, and poly-unsaturated fats have more kinks to them.

To be a solid, you have to pack tightly together

To think about what happens when you try to turn something into a solid, lets use the example of freezing liquid water. When water is warm (above 32 degrees Fahrenheit) water is a liquid. If you could zoom in really really close, you would see that the water molecules are zooming past each other with lots of space.

When the water starts getting colder, the molecules start moving slower. They eventually get so slow, that they begin to pack together. With water, when you get to 32 degrees, the water packs together so tightly that it becomes solid.

This is what happens to water when it freezes.

Every chemical has a different temperature that it decides to pack together into a solid. The harder it is to pack together, the colder it needs to be before it turns solid.

Kinky lipids are tougher to pack

Try to imagine packing together the lipids we saw above. If you were playing a game of tetris, which would ones would you want to work with?

The straight saturated lipids are a lot easier to pack together than the kinky unsaturated lipids. As a result, you need to bring the unsaturated lipids down much colder before they will become solid. For some lipids, this is the difference between being solid at room temperature (like lard) and being liquid (like vegetable oil).

You can see this every time you make bacon

Think of the last time you fried up a pan of some salty, crispy bacon.

You end up with a ton of liquid grease in the bottom of the pan. But this only lasts when it is hot. If you leave the grease in the pan to cool, it will turn solid. Sadly, this means that your bacon grease has lots of the unhealthy (but tasty) saturated fat. But it doesn’t stop me from sucking down half a pound without thinking (oops).

( yoda photo credit: Sweet One; tetris photo credit: k.steudel; bacon photo credit: nessguide)

Yes, some of these animals may be gross, but just because they’re cold blooded doesn’t always mean they’re cold.

It’s what’s on the inside that counts

In biology, we don’t call animals warm-blooded or cold-blooded. This name is a bit of a misnomer. The terms to use are endothermic and ectothermic. As it turns out, cold-blooded animals aren’t always cold, they just don’t make their own heat (for the most part).  Endotherms (warm-blooded animals, like us) can make our own heat. In fact, the word endotherm means “inside heat.” This means that if you stick us in a cold lake, our bodies will try to generate more heat to help regulate our internal temperature. We will actively try to bring our internal body temperature back to the normal, or homeostasis.

The environment can change the temperature of ectotherms

Ectotherms (cold-bloded animals), on the other hand, don’t actively regulate their internal body temperature. When you put them in the cold, their entire body cools down; along with its metabolism. If you put a snake in cold water, all of its body’s functions will slow down. This is why they like to bask in the sun after a big meal: it helps them digest.

What about fish? They live in very cold water.

Then, there are the fish (like the sea-raven depicted below) that live in icy-cold water. If they don’t regulate their own body temperature, aren’t their bodies the same temperature of the freezing water? Why aren’t they icicles too?

These fish are able to survive in the cold because they produce antifreeze for their blood. These chemicals, called antifreeze glycoproteins are produced in the pancreas of the fish. It’s similar to putting salt on the road to keep the roads from getting icy.

So, the next time you jump into a freezing lake, be thankful for the fact that you can warm yourself back up.

( fish photo credit stan_shebs; lizard photo credit: Aaron T. Goodman; cold swimmers photo credit: Ryan Forsythe)

Two different types of communicable pathogens under a Gram's Stain.

Communicable disease are usually caused by a pathogen, something nasty that gets in your body and makes you sick. Pathogens can be things like bacteria, viruses, fungi, and other things. The thing that they have in common is that they are caused by an infection. This infection is something that uses you to reproduce and pass to someone else.

Non-communicable diseases don’t communicate

You can’t catch a non-communicable disease because they aren’t caused by a pathogen. They are caused by something in your body breaking. Many examples of this include genetic diseases.

This girl has down's syndrome, caused by a genetic abnormality.

A disease like Down’s syndrome isn’t communicable because it is something deficient in the cells; you can’t pass that on.

Normally, cancer is non-communicable

Cancer happens when your cells forget to stop dividing. Your normal cells like to divide only as much as they need to. This can just happen when your cells get old; usually its not caused by something else. Though this is bad, it also means that you can’t catch someone’s cancer: you only get cancer when your own cells go bad.

The pink in the middle is cancer (squamous cell carcinoma). These cells used to be just like the normal cells next door.

Tazmanian Devil Cancer: trasmitted through bite

The wily cartoon Taz is a tazmanian devil. He (and his real counterparts) were beginning to die of a mysterious disease.

It turned out that, one tazmanian devil got a very aggressive tumor. These cells were able to grow and divide very fast. When this first animal took a bite at another of his friends, a couple of the tumor cells came along with the bite. Because they grow so well, they set up shop in the bite wound. Then this guy bites another; the cycle continues.

Cancer evolution plays by its own rules

This is a pretty spooky thought. We already know that cancer sometimes does some wacky things with natural selection. Could something like this happen with a human tumor cell? What would we do if it did? Leave a comment below to tell me what you think.

(bacteria photo credit: kaibara87; girl photo credit javier delgado esteban; cancer photo credit: Pulmonary Pathology; taz photo credit: mlvn.snmgl; tazmanian devil photo credit: Richard.Fisher)

Like these photos of a blue-green iris and computer art:

But no matter how much egg nog you have, you cannot see a color which you would describe as red-green (even if you stare cross-eyed at the Christmas tree).

Let’s shed some light on this:

The light that we can see is known as an electromagnetic wave, the same stuff that radio waves and microwaves are made of. Light travels in tiny bits called photons. The photons come from the sun, bounce off of things, and some of them make their way into our eyes. In short, when you see something, you are only really seeing it because your eyes can detect the light that gets bounced off of what you are looking at.

Wavelength in the world, color in your brain:

You have probably seen light that has been split by a prism, like this one:

A prism like this can separate the photons of light by their energy level, or wavelength. When a photon of a certain wavelength bounces into our eyes, our brain picks up the signal and you perceive the color we would all agree is red. Nothing is any color until your brain decides it is; it just reflects photons.

Blame it on the brain:

In the back of your eye, you have cells called cones, which are the main color detecting cells in your eye. When a photon hits the cones, they send a signal to your brain for processing. One of the leading theories on how your brain processes color information is called the opponent process theory.

It turns out that your eyes look at color in two channels: red vs. green and blue vs. yellow. Red and green oppose each other, and so do blue and yellow. Your eye looks at each combination of photons coming in, and calculates the amount in each channel.

The result?  Our brain first decides if something is red or green, then blue or yellow. Then it can mix the two channels. You can combine red and blue to get purple, but Lady Gaga won’t be wearing a red-green or blue-yellow headpiece at the grammys.

(eye photo credit: melloveschallah; blue-green smoke photo credit: Paralog; christmas tree photo credit: versageek; prism photo credit: hans s)

“What was the time of death detective?”

“When we arrived, rigor had begun to set in. I place time of death at 4 hours ago.”

This scene is typical of a CSI murder drama. The Medical Examiner steps on the scene and examines the body for signs of rigor mortis. Like clockwork, the muscles of a dead body begin to stiffen starting 3 hours after death. Full rigor comes on around 12 hours (the medical term for the body at this time is a “stiff”).

What’s the deal?

You’d like to think that when you die, you would finally get to relax. Why do your muscles want to postpone this well-earned relaxation by going into rigor? The answer has do to with the molecular motors of your muscle cells.

Myosin: Your muscles’ motors

When you move any part of your body, muscles contract to pull your bones the way they need to go. Your muscle cells do this by using a molecular motor called myosin, which tugs along a “rope” made out of protein. This is what it actually looks like (the red guy is myosin):

It doesn’t just do this on its own, you need energy to contract those massive biceps and rippling pectorals. Energy is something your body doesn’t have when its dead.

If myosin doesn’t have energy, why don’t muscles relax instead of tense up?

The thing about myosin is that, it acts like it is spring-loaded. You put in energy to reload the spring, then you release the energy to contract the muscle.

The process is similar to cocking a revolver. It takes some energy to pull the hammer back, but it doesn’t take any energy to get the gun to fire once its cocked.

To make matters worse for the muscle, myosin can’t release itself  from actin until it gets more energy to “re-cock” itself.

Result: The famous “stiff” corpse

When your killer comes around and does you in, your muscles don’t know that their energy supply is going to be running out. The unsuspecting myosin keeps going like nothing is happening, until it runs out of energy. Soon enough most of your muscle myosin is locked in the contracted position by the time the medical examiner finds you.

( dead man photo credit: The Rhumb Line; revolver photo credit: trawin)