changing size of earth

[lookeratclouds]

I did a back of the envelope calculation of the size of the earth as it was maybe 4 billion years ago using
the hubble constant, and it seems to have been about 2500 miles smaller in diameter, along with everything else in the universe of course. Does that figure seem close? I was trying to understand if there
was anything you could test for if you had access to both earths, the present one and the 4E9 years ago
one, if you had a time machine, wouldn't you also be squished by that amount relative you your own size in this time frame? I wonder if you would feel the change. I would go from about 6'2" to less than 5 feet tall and a bit skinnier! So if all the rulers get smaller and you cant see any differance, what about inner atomic forces? seems they would be closer together and therefore have a higher energy density, electrons in smaller orbits, therefore faster?, therefore more energetic?  Time would run faster also, maybe that would be what evens things out and make all the fundamental constants scale at the exact same pace. Seems like there should be SOMETHING measurable though, like if you had a time machine and could instantly go back to earth as it was 4 billion years ago, dodging meteorites along the way!

[Astronuc]

Please elaborate on your calculation with Hubble's constant.  Why would the Earth be smaller 4 billion years ago?  Then the universe was about 9-10 billion years old.

The origin of the solar system is believed to have ivolved a large clouds of matter (gas/dust) that accreted into the sun and surrounding planets.   The precise evolution of the solar system is quite fuzzy.

As for what one could test - probably the atomic constants and properties - e.g. ionization potential.  But then one must ask, are these properties invariant in time or in space.  As far as one can discern, emission spectra from many parts of the universe are fairly uniform - except of course for the red or blue shift - which IIRC seems also predictable.

AFAIK, no one has traveled in time, therefore the effects on one and one's instruments are highly speculative.

As for a smaller earth, the mass density would have been greater (perhaps), but the atomic sizes would not necessarily be smaller.  If they were, the electrons would have different wave characteristics, and perhaps be more energetic (deeper in the coulomb potential field).

Going back 4 billion, one might find a very hot earth which would be uninhabitable.

[Qazaq2003]

Astro,
 Please don't encourage him, he is obviously bozo flux. That is the most outlandish piece of crud I have seen posted on ES in a long time. Of course he isn't going to elaborate on his calculations with Hubble's constant, because his theory (sic) is made from whole cloth. Sorry about being a bit harsh there, but I call it as I see it. Q

[sonhouse]

It sounds like what he is referring to is the expansion of space, if space itself is expanding then maybe space is being "pumped" into each particle too so over time the particle or the whole earth gets larger. That idea was discussed in a recent Scientific American article about mistakes made by even professional astronomers, a lot of misconceptions made. I assume space can't be "pumped" into a particle so would be the same size 10 billion years ago as it is now. Only in open space would a "pumping up" take place. Does that sound like what he was talking about?

[yale]

yes, that is what the poster was describing.

The local effects of matter and energy stupendously dwarf the universal expansion.

An example is that the Milky Way galaxy and the Andromeda Galaxy are moving towards each other, even tho the universe is expanding. The local gravitational effects easily overcome the small, yet pervasive expansion.

yale