Tag Archives: Astrophysics

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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For All Mankind

Today we celebrate one of humanity’s greatest accomplishments. On July 20, 1969 — 45 years ago today — Neil Armstrong and Buzz Aldrin became the first humans to set foot on the moon. It was the height of the cold war, and the United States poured a huge amount of effort into space exploration as a way of competing with the Soviet Union. The Soviets beat us at many milestones, but the success of our human missions to the moon won the space race soundly for the United States.

Although Armstrong and Aldrin were sent to the moon to beat the Soviets, the plaque they left behind reads, “We came in peace for all mankind.”

The Apollo 11 lunar plaque. Image from nasa.gov

“We came in peace for all mankind.”

It could have read, “We claim this land for the United States of America.”

Given the times, it could have read, “Screw you, commies.”

But it said “we came in peace for all mankind.” This was an accomplishment for the men who personally walked on the moon, but it was not just for those men. It was an accomplishment for the United States, but it was not just for the United States. It was an accomplishment for the human race. Though these men and the country they represented were raised up by this accomplishment, they raised up every human being along side them.

Earlier that year, on April 17, 1969, Dr. Robert Wilson (1914-2000), a nuclear scientist, appeared in front of a congressional committee to ask for money to build the “linac” particle accelerator at the National Accelerator Laboratory (now known as Fermilab) in Batavia, Illinois. Senator John Pastore (D-RI) asked him, “Is there anything connected in the hopes of this accelerator that in any way involves the security of the country?” Dr. Wilson responded that,

“It only has to do with the respect with which we regard one another, the dignity of men, our love of culture. It has to do with these things… Are we good painters, good sculptors, great poets? I mean all the things that we really venerate and honor in our country and are patriotic about…It has nothing to do directly with defending our country except to help make it worth defending.” [emphasis added]

Scientific discovery is not just a tool we use to invent products that improve our lives. The knowledge and discovery and exploration themselves improve our lives. Most people think that science can make us great through the technology that it leads to. It isn’t that this is untrue, but this is only part of the picture. Science makes us great because it is a great achievement of humans. The accomplishments of science enrich our lives in the same way that we are enriched by the accomplishments of great poets, great composers and great artists. We share in the pride of the accomplishments of our scientists and we appreciate the beauty and wonder of their works. Science can indeed help us build planes and bombs and rockets that allow us to defend our country, but the fact that we carry out scientific research is a part of what makes us great and worth defending.

In 1972, during the Apollo 17 mission — the last time anyone sent live people to the moon — astronauts took a picture of the Earth from orbit. Known as “The Blue Marble,” this is one of the most famous photographs ever taken.

The Blue Marble. Photo taken by the Apollo 17 crew. Image from wikipedia.org

In 1990, the Voyager 1 spacecraft  photographed the Earth from 3.7 billion miles away — 40 times the average distance between the Earth and our Sun. The Earth is visible only as a tiny dot. This photograph became known as “The Pale Blue Dot” and inspired a book by Carl Sagan of the same title.

Photograph of earth taken from the Voyager 1 spaceprobe. Image from wikipedia.org

On July 19, 2013, the Cassini spacecraft took a picture of Earth through the rings of Saturn. At the time of the photo, the people of Earth were encouraged to contemplate their place in the universe and smile for the camera. People all over the world took part.

 

Photograph from the Casini spaceprobe. Earth can be seen as a blue speck in the center right of the photograph, in between the rings of saturn. Image from wikipedia.org

These photographs and events represent to us the collective accomplishments of the human species. Why would people in all corners of the Earth look up and smile for a photograph being taken too far away for their faces to be seen? Because they felt connected. These photographs do not particularly serve any scientific purpose, and they were not the point of these missions, but the photographs allow people to feel connected to the accomplishments that the photographs represent.

Consider if we discover an intelligent alien civilization at some point in the future. We might exchange some technology with them, and that might improve our lives. But to think of it only in terms of technology is missing the point. The discovery that we as intelligent life are not alone in the universe would profoundly change us. It would be the greatest discovery in all of human history.

Neil Armstrong died two years ago, so he is not able to share in today’s celebration, but his surviving family recommends a way to celebrate him:

“For those who may ask what they can do to honor Neil, we have a simple request. Honor his example of service, accomplishment and modesty, and the next time you walk outside on a clear night and see the moon smiling down at you, think of Neil Armstrong and give him a wink.”

I encourage you to go outside tonight and wink at the moon. Remember the accomplishments of Neil Armstrong and Buzz Aldrin 45 years ago, but also think of the collective scientific achievements of all humans throughout time.

 

 

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