Lawyers are trained to get ourselves quickly up to speed on any new issue brought through the door
by a client. We like to check and challenge assumptions by looking at facts and evidence. So we get pretty
bold at attacking just about any problem with logic and good, basic research.
Often, we need to be able to criticize and question our own scientific experts. There's a fun topic-of-the-week that provides an example -- the Supermoon. You'll see all sorts of commentary splashed around on the news and Internet about this phenomenon. It's simply where the moon comes closer to the Earth than it has for a couple of decades. So what? Is this a big ho-hum, or could there be some linkage to recent geological cataclysms. What's coming next week? How do you think about this problem? What if I told you that with just a few numbers and an Excel spreadsheet you can work out your own analysis quite quickly.
Here's what you do: Search on Google "apogee perigee distances" and jump to the second hit you see, titled "Lunar Perigee and Apogee Calculator." Copy-paste those dates and distances into Excel. Now you have the distances,but how do you figure the forces? Aha! Remember the apple! Try Googling "Newton gravity equation." Take the first hit -- Wikipedia "Newton's law of universal gravitation." You easily find that the force equals the gravity constant, G, times the mass of Earth in kilograms (EarthKG), times the mass of the Moon (MoonKG), with that product divided by the perigee distance squared. A couple more easy searches and clicks gets you the values for G and the masses of the Earth and Moon (in kilograms). Have your Earth-Moon distance in meters, and let Excel do its work. For example, =G*EarthKG*MoonKG/perigee^2" is what you enter into your spreadsheet cell to get the gravity force at perigee. Now, think just a little bit more about stressing the non-rigid Earth geological system with a slight perturbation in the form of a shifting pull-relaxation function over the time period of apogee-perigee. If you look only at perigee -- the moment of closest approach -- then you miss some of the pull-relaxation oscillation that can occur in this big wiggly system. Notice how superperigee comes right next to a super-apogee! You really want to be looking at the difference in gravitational force between the moments of adjacent apogee and perigee. My calculations show a 16% increase in this difference function during the current two-week period versus more normal periods. Adjusting down some for the moon being only 2/3 of tidal pull (the sun is about 1/3), this means you can estimate about 10-11% increase in the pull-relaxation forcing between the Earth and Moon during this Supermoon week versus a few months ago. In geology, unstable stressed fracture points may be momentarily balanced until some fairly minor perturbation triggers a slippage. And it may not take much of a percentage change in force to cause an event, or contribute to the cause of an event, in a stressed poised system. In my thinking, a 10-11% perturbation in tidal forcing is quite significant as an oscillatory perturbation upon a flexible, rebounding system such as the Earth’s crust. Remember, that tide pulls on rock, too.
Hmmm. Supermoon? But then, what do lawyers know?! That's why we hire experts to testify on the stand!
by a client. We like to check and challenge assumptions by looking at facts and evidence. So we get pretty
bold at attacking just about any problem with logic and good, basic research.
Often, we need to be able to criticize and question our own scientific experts. There's a fun topic-of-the-week that provides an example -- the Supermoon. You'll see all sorts of commentary splashed around on the news and Internet about this phenomenon. It's simply where the moon comes closer to the Earth than it has for a couple of decades. So what? Is this a big ho-hum, or could there be some linkage to recent geological cataclysms. What's coming next week? How do you think about this problem? What if I told you that with just a few numbers and an Excel spreadsheet you can work out your own analysis quite quickly.
Here's what you do: Search on Google "apogee perigee distances" and jump to the second hit you see, titled "Lunar Perigee and Apogee Calculator." Copy-paste those dates and distances into Excel. Now you have the distances,but how do you figure the forces? Aha! Remember the apple! Try Googling "Newton gravity equation." Take the first hit -- Wikipedia "Newton's law of universal gravitation." You easily find that the force equals the gravity constant, G, times the mass of Earth in kilograms (EarthKG), times the mass of the Moon (MoonKG), with that product divided by the perigee distance squared. A couple more easy searches and clicks gets you the values for G and the masses of the Earth and Moon (in kilograms). Have your Earth-Moon distance in meters, and let Excel do its work. For example, =G*EarthKG*MoonKG/perigee^2" is what you enter into your spreadsheet cell to get the gravity force at perigee. Now, think just a little bit more about stressing the non-rigid Earth geological system with a slight perturbation in the form of a shifting pull-relaxation function over the time period of apogee-perigee. If you look only at perigee -- the moment of closest approach -- then you miss some of the pull-relaxation oscillation that can occur in this big wiggly system. Notice how superperigee comes right next to a super-apogee! You really want to be looking at the difference in gravitational force between the moments of adjacent apogee and perigee. My calculations show a 16% increase in this difference function during the current two-week period versus more normal periods. Adjusting down some for the moon being only 2/3 of tidal pull (the sun is about 1/3), this means you can estimate about 10-11% increase in the pull-relaxation forcing between the Earth and Moon during this Supermoon week versus a few months ago. In geology, unstable stressed fracture points may be momentarily balanced until some fairly minor perturbation triggers a slippage. And it may not take much of a percentage change in force to cause an event, or contribute to the cause of an event, in a stressed poised system. In my thinking, a 10-11% perturbation in tidal forcing is quite significant as an oscillatory perturbation upon a flexible, rebounding system such as the Earth’s crust. Remember, that tide pulls on rock, too.
Hmmm. Supermoon? But then, what do lawyers know?! That's why we hire experts to testify on the stand!
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