5 ms·
No. A human being 4.12E+12 meters tall, standing on the equator, would have their head moving at the speed of light due to the rotation of the earth. At that
by pklausler 10y ago
No.
A human being 4.12E+12 meters tall, standing on the equator, would have their head moving at the speed of light due to the rotation of the earth. At that point, their experience of time would essentially stop, and reproduction would cease. Also, cosmic rays and lack of O2 would begin to distract the subject from reproduction with cumulative effects from suffocation and radiation burns long before evolution could raise humans to the aforementioned 4 billion km height.
There are other considerations (viz. angular momentum, occasionally passing the human through the Sun at roughly knee height, lunar collisions, &c.) So, anyway, no, we can't keep getting taller.
- foobarian 10y agoYou assume they would be standing up.
- Franciscouzo 10y agoWe can indeed keep getting taller if the human height series converges
- dkbrk 10y agoYou ignore that it's entirely possible to have an infinite, monotonically increasing sequence with a fixed upper bound. Yes, people could keep getting taller without ever exceeding some defined limit. However we would begin to encounter problems as the sequence of heights approached said limit. The deltas would become smaller than the precision of our equipment, and later would become smaller than physically meaningful scales (i.e. length scale of an atom). In this limit, I think it would be reasonable to generalise "keep getting taller" to "probabilistically grow by the smallest physically meaningful amount on an arbitrarily long timescale", in which case this continues to be well defined as t→∞ even if it would be difficult to physically observe.
- pklausler 10y agoI omitted reference to convergence on a limit from my brief note because it's self-evidently obvious to even the most casual observer that the argument is no less specious than saying that one cannot simply walk into Mordor. There is a practical limit to human height, and rather than simply converging upon it while remaining less than that limit by some nonzero amount, humans will actually reach that height in a finite duration of time and then stop evolving altogether, at least along that particular dimension.
- khc 10y agoYou would be right if humans are made of numbers and not atoms.
- tlb 10y agoBut humans are made of many atoms, and the measurement is averaged over some time period in which molecules vibrate many times, so there is no limit to the precision with which they can be measured.
- personjerry 10y agoForgive me if I've misunderstood, but isn't your proposed problem akin to Zeno's paradox of infinite distance, where we never reach anywhere because first we need to go 1/2 the distance, then 1/2 of that, etc.? Which, of course, is resolved in math by limits, and in the real world by discrete units (i.e. atoms).
- paulmd 10y agoAlso, there is a finite limit to the signal delay that can be reasonably endured. Neuron signals travel at around 50 M/s. The giraffe probably represents the evolutionary limit of how far the brain can be from the feet before you start stumbling and falling over. This is a rather interesting post on some of the potential mechanisms of giraffe balance. http://psychsciencenotes.blogspot.com/2013/08/why-dont-giraffes-fall-over-more-often.html http://psychsciencenotes.blogspot.com/2013/08/why-dont-giraf...