Recent content by Phobos

Soul of the Night by Chet Raymo (like Sagan, Raymo makes the universe soulful)

It's important to understand that evolution is not a ladder of progress that leads to humans. It's a great branching of different variations that adapt to different environments. Modern fish are just as "evolved" as modern humans. In the evolutionary past, some types of fish had the right...

Hey, my thread is still here...10 years later! Thanks for keeping this (and PF) going everyone!

In the US, we often measure elevation with respect to a NGVD (National Geodetic Vertical Datum).

Yep, it appears that anything "before" the Big Bang is essentially "outside" of this universe and is inaccessible to us (no information available to study). But there's hopes that there will be clues somewhere (e.g., echoes in the cosmic background radiation?) Aside from that, we're stuck...

...and tidally locking the moon

As noted above, galaxies move with respect to each other due to gravitational interactions (orbiting each other within galaxy clusters). Galaxy clusters also "move" apart from each other due to the expansion of space.

The answer to your last question is yes. The Hubble constant which is used to measure the expansion of the universe is based on an expansion speed per distance from us. So, picture the universe expanding uniformly in all directions. So, the further away a particular object (e.g., galaxy) is...

Gravitational interaction between the Earth and Moon raises tides, not just in the Earth's oceans, but also in the rock of the Earth and Moon. As that raised section of the Earth/Moon moves out of alignment (due to the rotating Earth/Moon), gravity pulls back on it and brakes the rotation...

Which will be right around the time the swollen sun is turning the Earth into a cinder.

I'd be curious to know where the aliens hid all that mass from the moon's interior (and why!). They must have also reinforced the surface to withstand meteorite impacts and the continual deformations from tidal interactions with the Earth. ;) But perhaps our future colonization of the moon...

And an arbitrary 0,0,0 reference point in space?

(1) The virus infects a cell, tricks the cell into making more copies of that virus until the cell ruptures and sends those new virii out to infect other cells. Fevers, runny noses, etc. are some of our bodies attempts to get rid of the virus. Of course, some types of virus use runny noses as...

In the case of pet dogs, their "ecosystem" testing their fitness is their relationship & cohabitation with humans. (as chroot was saying) So, the more pleasing a particular variation is to humans, the more that variation will be selected for. (shifting frequency of alleles = evolution) Note...

Particles other than atoms exist.