A brief lesson in physics
08/08/16 04:43
OK friends, I had a lot of fun yesterday blogging and preaching about something about which I know very little, namely physics, specifically particle physics. So I thought that I would follow up this morning with another blog about something about which I know equally little, that is, the Second Law of Thermodynamics. Since we live in an orderly universe that abides by the laws of physics, it makes sense that I ought to have some idea about those laws.
But first, a little personal information. Nearly four decades ago, when we were seminary students, we formed a close friendship with a family from Australia. When we completed our educations, we began our ministries, they in Australia and we in North Dakota. Over the years, the friendship has remained strong and vibrant despite the great distances between our homes. When we have the opportunity to get together, which we seem to find about every five years or so, our conversations continue as if we had been talking daily all along. It is a joy to know that friendship truly transcends distance and that the values that we hold dear are still relevant even after the passage of time. Ten years ago we were able to travel to Australia with our family and spend time with our friends. It was something that we will always treasure and remember.
Anyway, those friends are coming to visit us tomorrow and we are excited and happy. Our daughter and son-in-law will also arrive tomorrow as she is eager to see our friends and to introduce her husband to them. Next week our son and grandson will travel to meet us in Montana for an even greater reunion. First, however, we are going to invest part of this week showing them South Dakota. Tony recently retired after serving for a decade as the National Director of Multicultural and Cross-cultural Ministry of the Uniting Church in Australia. As a result he is very interested in our partnerships with Lakota Congregations and their work on our reservations, so we will be traveling to Bridger to view some of the work of that congregation later this week.
So, the past couple of days have involved the normal kind of house cleaning that is a part of preparing for guests. These people are family and friends, so we don’t need to alter our lifestyle. On the other hand, we do want them to feel welcome and we are excited that they are coming, so a little extra window washing and preparing are in order.
Combine that with the fact that our church is having a rummage sale in a couple of weeks and it is an opportunity for us to donate some the the accumulation of 21 years of living in the same house. So, we’ve made some modest donations to the rummage sale and have been doing a little bit of sorting of our things, which seem to accumulate no matter how hard we are able to envision a more minimalist existence.
Which brings us to the second law of thermodynamics. I know you’ve been waiting for this. Simply stated the second law of thermodynamics is that an isolated system’s entropy never decreases. To state it in a different manner, there are certain things that cannot be reversed. Moving away from thermodynamics, slightly, There are certain things that occur only in one direction. You can’t unscramble an egg. A crashed car cannot reassemble itself. Smoke doesn’t flow down the chimney and back into the fire. We accept these things simply by our observation of the universe. In physics. Entropy is an all pervasive natural force, similar in importance to gravity or electromagnetism. It relates to the “flow” or directionality of time. Time only goes in one direction.
Here is a simple example: You have a cup of very hot coffee that you would like to drink as soon as possible, let us say, within 5 minutes. Should you first add the desired quantity of cold milk to the coffee and then let the coffee sit for 5 minutes? Alternatively, do you let the coffee sit for 5 minutes and then add the same quantity of milk?
The answer is not intuitive but it is simple, if we are familiar with the Second Law: The rate of heat exchange between the hot coffee and the ambient air depends on their temperature differential. The higher the temperature differential, the faster will be the rate of exchange. Within the 5-minute waiting period, heat transfers to the air at a higher rate if we do not add the cold milk initially to the coffee. If we add the milk at the beginning, instead of at the end of the 5 minutes, the energy transfer will slow down and the coffee will be markedly hotter at the end of 5 minutes.
OK, pastor, this really doesn’t have anything to do with everyday life, unless you really care about the quickest way to cool your coffee. Apply the principle to the universe, however, and you will see how the principle applies to what is going on in my life today. Instead of thinking about the energy in a hot cup of coffee, think, for a moment about all of the energy in the universe. The amount of energy in the universe was established at the time of the Big Bang. At that point, energy was extremely concentrated and ordered. Since then, the universe has expanded vastly and energy has become more diluted and randomized. It is inherent in the nature of the universe that this process must and will continue. If it were to stop, the universe would cease to exist.
Just as the flow of time is one way, the expansion of the universe is one way. It is a fundamental process of the universe that energy becomes more diluted and randomized with the passage of time. This cannot be reversed. The universe literally flows form order to chaos.
Which explains why although we work hard to keep our house clean and our possessions organized disorder continues to creep into our lives. It is a universal law: paint peels, hot coffee turns cold, investments go sour, and the garage gets messy. It isn’t just that anything that can go wrong will go wrong. More precisely, according to the second law of thermodynamics, anything that can go wrong must go wrong.
Now that you’ve got that, I can explain quantum mechanics to you. But that discussion will have to wait for another day. I’m out of space for today.
But first, a little personal information. Nearly four decades ago, when we were seminary students, we formed a close friendship with a family from Australia. When we completed our educations, we began our ministries, they in Australia and we in North Dakota. Over the years, the friendship has remained strong and vibrant despite the great distances between our homes. When we have the opportunity to get together, which we seem to find about every five years or so, our conversations continue as if we had been talking daily all along. It is a joy to know that friendship truly transcends distance and that the values that we hold dear are still relevant even after the passage of time. Ten years ago we were able to travel to Australia with our family and spend time with our friends. It was something that we will always treasure and remember.
Anyway, those friends are coming to visit us tomorrow and we are excited and happy. Our daughter and son-in-law will also arrive tomorrow as she is eager to see our friends and to introduce her husband to them. Next week our son and grandson will travel to meet us in Montana for an even greater reunion. First, however, we are going to invest part of this week showing them South Dakota. Tony recently retired after serving for a decade as the National Director of Multicultural and Cross-cultural Ministry of the Uniting Church in Australia. As a result he is very interested in our partnerships with Lakota Congregations and their work on our reservations, so we will be traveling to Bridger to view some of the work of that congregation later this week.
So, the past couple of days have involved the normal kind of house cleaning that is a part of preparing for guests. These people are family and friends, so we don’t need to alter our lifestyle. On the other hand, we do want them to feel welcome and we are excited that they are coming, so a little extra window washing and preparing are in order.
Combine that with the fact that our church is having a rummage sale in a couple of weeks and it is an opportunity for us to donate some the the accumulation of 21 years of living in the same house. So, we’ve made some modest donations to the rummage sale and have been doing a little bit of sorting of our things, which seem to accumulate no matter how hard we are able to envision a more minimalist existence.
Which brings us to the second law of thermodynamics. I know you’ve been waiting for this. Simply stated the second law of thermodynamics is that an isolated system’s entropy never decreases. To state it in a different manner, there are certain things that cannot be reversed. Moving away from thermodynamics, slightly, There are certain things that occur only in one direction. You can’t unscramble an egg. A crashed car cannot reassemble itself. Smoke doesn’t flow down the chimney and back into the fire. We accept these things simply by our observation of the universe. In physics. Entropy is an all pervasive natural force, similar in importance to gravity or electromagnetism. It relates to the “flow” or directionality of time. Time only goes in one direction.
Here is a simple example: You have a cup of very hot coffee that you would like to drink as soon as possible, let us say, within 5 minutes. Should you first add the desired quantity of cold milk to the coffee and then let the coffee sit for 5 minutes? Alternatively, do you let the coffee sit for 5 minutes and then add the same quantity of milk?
The answer is not intuitive but it is simple, if we are familiar with the Second Law: The rate of heat exchange between the hot coffee and the ambient air depends on their temperature differential. The higher the temperature differential, the faster will be the rate of exchange. Within the 5-minute waiting period, heat transfers to the air at a higher rate if we do not add the cold milk initially to the coffee. If we add the milk at the beginning, instead of at the end of the 5 minutes, the energy transfer will slow down and the coffee will be markedly hotter at the end of 5 minutes.
OK, pastor, this really doesn’t have anything to do with everyday life, unless you really care about the quickest way to cool your coffee. Apply the principle to the universe, however, and you will see how the principle applies to what is going on in my life today. Instead of thinking about the energy in a hot cup of coffee, think, for a moment about all of the energy in the universe. The amount of energy in the universe was established at the time of the Big Bang. At that point, energy was extremely concentrated and ordered. Since then, the universe has expanded vastly and energy has become more diluted and randomized. It is inherent in the nature of the universe that this process must and will continue. If it were to stop, the universe would cease to exist.
Just as the flow of time is one way, the expansion of the universe is one way. It is a fundamental process of the universe that energy becomes more diluted and randomized with the passage of time. This cannot be reversed. The universe literally flows form order to chaos.
Which explains why although we work hard to keep our house clean and our possessions organized disorder continues to creep into our lives. It is a universal law: paint peels, hot coffee turns cold, investments go sour, and the garage gets messy. It isn’t just that anything that can go wrong will go wrong. More precisely, according to the second law of thermodynamics, anything that can go wrong must go wrong.
Now that you’ve got that, I can explain quantum mechanics to you. But that discussion will have to wait for another day. I’m out of space for today.