A New Spin

A New Spin (cont'd)

1. The bigger they are ...

During the court case that followed the super-tanker Exxon Valdez environmental disaster, it was revealed that the crew initiated a change-of-course maneuver which would have taken some 45 minutes to complete (it was never completed since the ship ran aground shortly thereafter). A kayak could have turned around in a matter of seconds, once on a dangerous course, but for a super-tanker it's just not possible.

Why can't a super-tanker turn on a dime like a kayak can? In order to answer this question you may have to go back to your high school days. You may remember a physics experiment of a mass hanging on a spring performing a 'Simple Harmonic Motion'. You may recall that when the mass was increased it still bobbed up and down, but more slowly. It was said that as the mass increases, the 'Physical-System' takes on a lower 'Natural-Frequency'.

Nature clearly dictates that as size increases, the natural frequency decreases, and hence the system slows down. Therefore, one would expect a big bell to have a low tone (a sound of a low frequency) i.e., having slow-changes; and a small bell to have high tone (a sound of high-frequency) i.e., having fast-changes.

piano The next time you have a chance to peer into a grand-piano's entrails, notice that the strings on the left side (corresponding to the low keys) are long and thick, i.e., having high mass (big) while those on the right (the high keys) are short and thin, i.e., having low mass (small).

The same principle applies to animals. We intuitively associate a deep low-pitched bark with a big dog and a high pitch as belonging to a yappie little fellow. It follows that whether for objects or animals, the bigger they are, the more sluggish they have to be.

2. Is there a limit to growth?

As animals grow in size there must be a point where they can no longer sustain life since they become too slow to function. In order to test the validity of this statement we need to conduct a little 'Thought-Experiment'.

Love this low-carb stuff

Let's assume that this 100-ton plant-eater, which is often characterized as not having to move much, is just doing precisely that. Namely, it's just lying there on its fat stomach amidst the lush vegetation which literally grows into its mouth. All it has to do is just bite mouthfuls of the stuff to feed itself.

Since the animal is cold blooded we can safely disregard any energy it may require for its normal bodily function. The only energy it expends is directed to its mouth muscles moving its enormous jaw up and down constantly in the process of feeding itself. Every mouthful it takes, on the other hand, contains exactly that amount of energy in vegetation so that the energy expended is equal to the energy gained and the animal is doing fine-thankyou.

Now, let that animal grow to twice its size. In order to maintain its proportion, it grows eight times in volume and weight (it has to grow twice in length, twice in width... you get the picture). Since the jaws become eight times their size and weight, their muscles require eight times the energy in order to make them function. However, the volume of the mouth also grows eight times and every mouthful contains now eight times the amount of vegetation and energy, so there should not be any problem, right? Wrong!

Having grown considerably larger, the animal becomes slower as we have seen above. Although, its mouth can deliver the required energy in each mouthful, it does that at a much lower-rate than the jaw muscles require to constantly operate. Consequently, unless that animal can transform itself to a government or to a major corporation (both of which can thrive on a deficit) it's doomed!

Next: Not convinced yet? What does rate have to do with it?

i. 'What is this?'

ii. --The short answer:

iii. --The long answer:

iv. For the impatient:

v. 'What is next then?'

1. The bigger they are ...

2. Is there a limit to growth?

3. Not convinced yet? What does rate have to do with it?

4. Why aren't any such big animals alive today?

5. What, then, made it possible for them to take their place in the earth's history?

6. But aren't weight and size one and the same?

7. Are we talking change in gravity, then?