Tag Archives: Planet

The Universe is Vast, And Why That Bothers Me

The word “vast” gets tossed around a lot to describe things like the backseat of an SUV, or a big lawn or the open ocean. These things can all be vast, depending on your frame of reference, but if there is anything that can truly be described as “vast” it is the universe.

The size of the universe defies any adequate description or human comprehension. Consider light. Light travels at the cosmic speed limit of 186,000 miles per second.

Chicago satellite image

Satellite view of Chicago

I live in Chicago, and I am often amazed at how big this city is. I could spend my whole life exploring this city and not get to see everything. Google tells me that there are 4300 miles of road in Chicago — longer than the United States is wide — but light could travel every road in the entire city 43 times in one second. One second to travel the entire distance that my first car traveled in its entire lifetime. One second to travel around the Earth’s equator seven times.

Our sun is 93 million miles from where I am sitting. At a steady pace of 3 miles per hour, it would take 3500 years to walk to the sun without any breaks for eating or sleeping. The same light that can circle the whole earth seven times in one second takes 8 whole minutes to get from the sun to our planet. Along the way, there are two planets, one about the same size as earth, and one a bit smaller. Venus has a surface area of 177 million square miles — that’s over 750,000 Chicagos. There are six more planets in our solar system, a handful of dwarf planets, an asteroid belt, an Oort cloud, and more.

The nearest star to our own is Proxima Centauri. Light from our sun takes 4.3 years to get there. 4.3 years going as fast as it is possible for anything to travel.

Our planet is located in a backwater arm of the Milky Way Galaxy. Light takes 100,000 years to travel its diameter. The same light in the same time could circle the earth over 20,000,000,000,000 (20 trillion) times.

You Are Here Milky Way

The nearest galaxy to the Milky Way is the Andromeda Galaxy. It is 220,000 light years across, and 2.5 million light years from Earth. Although it contains somewhere in the order of one trillion stars, the entire galaxy is only visible from Earth as a single point of light.

The observable universe is 93,000,000,000 (93 billion) light years across. Light would take 93 billion years to go from one end of the universe that we know to the other. There is more universe out there, but the light from those parts hasn’t reached us yet because the universe isn’t old enough. The universe is only 13 billion years old.

The observable universe is estimated to have around 100-200 billion galaxies. We don’t know exactly how many there are, because it would take too long for our instruments to count them all. And again, there is more to the universe than what we can see. We don’t know how much more because, well, we can’t see it.

The Hubble "Ultra Deep Field"

The Hubble “Ultra Deep Field” is a view of part of the universe when it was less than a billion years old.

I hope I have given a glimpse of just how big the universe is. It is impossible for me to say exactly how big it is, not just because nobody knows, but because the size is completely incomprehensible. It defies language to describe it, and our brains to understand it. Even if the exact size were known, the number expressing it would be meaningless.

A lot of people hear how big the universe is and it makes them feel small. We are the center of our own lives, and what goes on in our lives is important to us. People used to believe that the Earth was the center of the universe because they couldn’t get their heads around the fact that we are unimportant. But to the universe, we are less than unimportant. For the sake of comparison, a speck of dust is in the order of 100µm (100 nanometers) wide. I am a little shy of 2 meters tall. I am therefore approximately 20 million times the size of a speck of dust (length, not volume).

The Earth has a diameter of about 12,000 miles. Our galaxy has a diameter of about 600,000,000,000,000,000 (600 quadrillion) miles. Our galaxy alone is 50 trillion times bigger than the Earth. People like to give “a speck of dust” as a measure of insignificance, but to our galaxy alone, the earth is far, far less significant than a speck of dust is to a human. And to the universe, our entire galaxy is insignificant. It is perfectly understandable that the universe makes some people feel small.

calvin dust speck

The size of the universe bothers me, too, but not because it makes me feel small. It has never been a problem for me to reconcile my own insignificance in the scheme of things.

I am troubled by the fact that I will spend my life exploring Chicago. I will spend my life getting to know one or two dozen people really well, a have a passing familiarity with maybe one or two hundred more. If I were still a researcher, I would spend my life trying to discover as much about the world as I could. As a non-researcher, I will spend my life learning as much of what others have discovered as I can. But there is so much that I will never know.

For all of the things we know about earth, there is so much more that we don’t know. We are just now starting to discover how common other planets are in our galaxy.

We know that the universe is believed to be about one quarter dark matter, but we don’t even know what dark matter is.

When I look up in the sky and see all that I can see, and understand what I can’t see, it makes me sad that I will never get to know so much of what is out there. So many galaxies. So many stars. So many planets. And I have to spend my life on just this one, with only my short life to see what I can see. There is so much to see on Earth, but the universe holds sights that we cannot possibly fathom.

The "Pillars of Creation"

The “Pillars of Creation”

I am troubled because I am a scientist, and I am greedy. Scientists are driven by the knowledge of the things we do not yet know. We see a hole in our knowledge and we want to fill it in. We are humbled by the knowledge of what we do not yet know, and seeing the vastness of the universe can be crushing.

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What Does It Mean To Be Supernatural?

Image from clipartpanda.com

Halloween is coming up, and popular culture is being filled its annual dose of references to the supernatural (including the recent season premier of the show Supernatural, which is probably not a coincidence). Ghosts, monsters, black magic, vampires, witches, and others all fall under this umbrella of “the supernatural.”

But what does it mean to be supernatural?

My dictionary defines “supernatural” as “(of a manifestation or event) attributed to some force beyond scientific understanding or the laws of nature.”

Being beyond scientific understanding is actually very mundane. Most of the way the brain works is beyond our current scientific understanding, but no serious researcher is throwing up his or her arms and declaring it supernatural. The relationship between mass and energy was beyond scientific understanding until Albert Einstein figured it out. The origin of mitochondria and chloroplasts were beyond scientific understanding until Lynn Margulis figured it out. Every issue of every scientific journal is filled with things that were beyond the understanding of science just a year or so prior. This is not what people mean when they say that something is supernatural. They mean the second thing — beyond the laws of nature. The word supernatural literally means “above nature,” or, more figuratively, outside or separate from nature.

But what is nature and what are its laws?

Consulting my dictionary once again, “nature” is defined as “the phenomena of the physical world collectively, including plants, animals, the landscape, and other features and products of the earth, as opposed to humans or human creations.” And once again, my dictionary fails to provide a completely cogent or useful definition. If humans and our creations are not natural, does that mean that the computer I’m writing on is supernatural? Again, no one would reasonably make this claim. The first part of this definition, “the phenomena of the physical world collectively,” is actually pretty good as it is. Nature, or the physical world, is made up of two things: matter and energy, which Einstein showed us are the same thing. Nature is everything that exists. It is all of the animals, plants, fungi, bacteria and all of the rest of life. It is all of the rocks and minerals and water and air. Even humans, which are animals, are part of nature. Everything beyond our planet is part of the natural world, as well. All of the undiscovered types and forms of matter and energy are part of nature. Every answer to an empirical question is part of nature, and it is the job of scientists to discover nature as it exists.

Are ghosts real? This is an empirical question because the answer is not subject to ideology or personal preference. It’s not possible for ghosts to be real for me but not real for someone else, any more than  the statement “the earth’s atmosphere is 78% nitrogen” can be real for me but not real for someone else. Correct answers to empirical questions are correct whether you like it or not. Likewise, either ghosts are real or they are not. If they are real, they are part of nature, and are therefore natural phenomenon. It may come as a surprise to people that, if ghosts are real, it will be scientists who discover them. This is true of everything else that is commonly labeled as “supernatural.” If everything that exists is part of nature, then what does that mean? If something is truly supernatural, it doesn’t exist.

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Sex With Aliens

Science fiction is full of humans interbreeding with intelligent aliens from all over the galaxy.

In the original Star Trek series, Captain Kirk mates with a wide variety of aliens, although he never fathers any children with them that we know of. Spock is half Human, half Vulcan. There are several characters in Star Trek: The Next Generation who are the result of alien-human mixing, as well. Worf is 100% Klingon, but his wife, K’Ehleyr, is half Klingon and half Human. Their son, Alexander, is therefore one quarter Human and three quarters Klingon. Deanna Troi is half Human, half Betazoid. The list goes on and is certainly not limited to Star Trek.

Star Trek’s Spock is half Human and half Vulcan. Image from wikipedia.org

I hope I’m not ruining anyone’s fantasy by pointing out up front that this is not even remotely plausible.

Imagine a human trying to produce offspring with an insect or a tree. Once you’ve stopped laughing, imagine trying to do the same with a bacterium, which is as distantly related from humans as you can get on Earth. Now consider that reproducing with a life form from another planet is far less likely to work out than trying to reproduce with a bacterium from Earth.

For two different species to be reproductively compatible, they cannot have very much evolutionary distance between them. Zebras (Equus zebra), horses (Equus ferus) and donkeys (Equus africanus) can all reproduce with one another. Lions (Panthera leo) and tigers (Panthera tigris) can sometimes produce offspring. The common chimpanzee (Pan troglodytes) and the bonobo (Pan paniscus) can produce offspring. (As is typical of cross-species hybrids, the offspring of these pairs are not fertile themselves.) I hope you noticed a commonality among all of these matches: they are all in the same genus. Lions and tigers are both in the same genus (Panthera) and they can sometimes reproduce together, but neither the lion nor the tiger can reproduce with a chimpanzee or a zebra because they are not closely related. This is not a hard and fast rule, though. Many species that are in the same genus cannot reproduce together, and occasionally species that are not in the same genus can reproduce together.

The liger is a hybrid between a tiger (Panthera tigris) and a lion (Panthera leo). Image from wikipedia.org

Life on Earth began somewhere between 3 and 4 billion years ago. Since then, life has evolved and diversified to produce the wide range of species that we see today. Another planet with life would have had its own origin and its own evolution to produce whatever diversity that planet has in whatever amount of time it took. An intelligent species on another planet would be unable to reproduce with most of the other species on its planet, just as most species on Earth cannot reproduce with one another. Humans are not able to reproduce with any other species on our planet. Even chimpanzees and bonobos, which are our closest evolutionary relatives, cannot produce offspring with humans (though it is not for a lack of trying). We share almost 99% of our DNA with chimpanzees, and are physically capable of mating, and yet we cannot reproduce with them. So what are the chances of being able to reproduce with a species that evolved from a completely separate origin of life? In this particular case, the likelihood is roughly equal to the percent of our DNA that we share: 0%.


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