Starship Asterisk*

by **geckzilla** » Sun Sep 30, 2007 12:37 am

Assuming they used a stable isotope, nope.

by **goredsox** » Sat Sep 29, 2007 6:57 pm

Hey I thought a kilogram was the weight of a liter of water under certain precise conditions (temp, pressure). I didn't know the definition was dependent on a musty old block of platinum locked up in France.

Also the news article said it contained Iridium too. Doesn't that decay?

by **geckzilla** » Sat Sep 29, 2007 12:01 am

Because there were a bunch of them distributed all around the world so that other countries would have their own means of discerning the weight of the kilogram. The difference wasn't caused by the one weight by itself but rather its comparison to the other weights. Well, that's what I read anyway.

by **jimsaruff** » Fri Sep 28, 2007 9:44 pm

Very good point, rigelan.

So how do you think they determined there was a 50 microgram difference?

by **BMAONE23** » Fri Sep 28, 2007 5:10 am

rigelan wrote:Well, masses are measured using balances.

The force of gravity upon the mass is compared to the force of gravity upon a second mass. If the gravity had changed, it should have absolutely zero effect upon the mass of the iridium-platinum kilogram standard. The balance would still be level because both masses would have less gravitational force upon them.

Nice Point

by **rigelan** » Thu Sep 27, 2007 9:41 pm

Well, masses are measured using balances.

The force of gravity upon the mass is compared to the force of gravity upon a second mass. If the gravity had changed, it should have absolutely zero effect upon the mass of the iridium-platinum kilogram standard. The balance would still be level because both masses would have less gravitational force upon them.

by **jimmysnyder** » Thu Sep 27, 2007 7:48 pm

BMAONE23 wrote:Electrons have mass weight, though the entire mass might become unstable if too many were ripped free from theit host atoms, but could those few ambient cosmic rays that manage to reach the earths surface cause a gradual stripping of electrons from the mass?

The lack of 50 micrograms worth of electrons would render the mass so positively charged it would flash sparks reaching all the way to Aix-la-Chapelle

by **BMAONE23** » Thu Sep 27, 2007 5:32 pm

Electrons have mass weight, though the entire mass might become unstable if too many were ripped free from theit host atoms, but could those few ambient cosmic rays that manage to reach the earths surface cause a gradual stripping of electrons from the mass?

by **Galactic Groove** » Thu Sep 27, 2007 1:25 pm

not sure if only 200 years would be long enough (if indeed they were created in 1800), but what about the half-life of the material the cylinder is made of?

EDIT: Nevermind, if it's Platinum then there is no halflife. But then again, what if there were other impurities present in the cylinder?

by **geckzilla** » Thu Sep 27, 2007 1:10 pm

I wouldn't be surprised if some Frenchie just got finger oils on it and over the course of 200 years it flowed off the thing.

by **auroradude** » Thu Sep 27, 2007 8:53 am

Has evaporation ever occured to anyone?

If I am thinking correctly, even though most atoms or molocules of a mass might not be at the point of turning liquid or gaseous from a solid at the time, some of them, maybe only a few of them, are. They just bounce around all day and slap each other around and some of them get hit "just right" and it sends them into orbit, or right out of it.
They leave the mass.

by **jimsaruff** » Thu Sep 27, 2007 5:38 am

It's the International Standard Kilogram cylinder. I believe it is platinum and some one or two other metals. It was formed in the 1800's, I believe.

Did you not see in the news a week or so ago that it had mysteriously lost 50 micrograms, as I recall. They made nine of these standard kilogram cylinders and kept one under lock and key (I imagine the others were also) under very controlled conditions. The rest were distributed internationally to set the agreed upon weight for the kilogram.

Anyhow, apparently they weighed the standard of the standards recently and it was 50 micrograms lighter. I was wondering if, as unimaginable as it seems, just how much of an increase in the radius of the earth would produce just such a loss.

Sorry if I went on too long here.

by **BMAONE23** » Thu Sep 27, 2007 5:04 am

what does the cylinder contain?

If something wet, possible evaporation. If something dry, maybe desication of a minute ammount of water

by **BMAONE23** » Thu Sep 27, 2007 5:02 am

hungry mouse???

by **jimsaruff** » Thu Sep 27, 2007 12:47 am

Did anyone ever explain the 'lost 50 micrograms' of the International Kilogram Cylinder in Paris?

by **rigelan** » Wed Sep 26, 2007 10:48 pm

Assuming a perfectly spherical earth, The gravitational acceleration at the surface of the earth would be a=G M / R^2

G is a constant. And in this particular situation, we are keeping the (M)ass of the earth constant, and yet expanding the (R)adius of the earth. So M is a constant, but R is increasing.

Since R is on the bottom side of the equation, as R increases, (a)celleration would decrease.

So if the earth expanded without changing its mass, the acceleration due to gravity on the surface of the earth would be less.

by **geckzilla** » Wed Sep 26, 2007 7:18 pm

You guys better tell Google to take into account the expanding of the earth's circumference before they lay their fiber optic cable across the pacific...

by **Galactic Groove** » Wed Sep 26, 2007 2:26 pm

auroradude wrote:It sure would be interesting to compare seismic records and tectonics from another planet about the size of Earth without a moon...
...say Venus for example.

Is there any "tectonic" activity on Venus? Venus is constantly turning itself inside out so I dont' believe that would allow for much in the way of plate development like we have here on Earth.

by **Galactic Groove** » Wed Sep 26, 2007 2:11 pm

rigelan wrote:Intertnet. If the earth has become less dense, then yes it would affect the gravity at the surface of the earth. It would be slightly less. But it would not affect how the earth's gravity pulls on the moon or any such other force, only the force on the surface of the earth.

Are you sure about that??? Last time i checked, gravity doesn't pick an area to affect more than another area. If gravity is recorded as being weaker in one area, it'll be weaker everwhere else too, regardless of distance.

by **rigelan** » Wed Sep 26, 2007 2:28 am

Intertnet. If the earth has become less dense, then yes it would affect the gravity at the surface of the earth. It would be slightly less. But it would not affect how the earth's gravity pulls on the moon or any such other force, only the force on the surface of the earth.

But I would be at a loss to know what particular item to look for in the history of the earth. Water levels? Rock densities?

by **inertnet** » Tue Sep 25, 2007 11:47 pm

Suppose the Earth was smaller and more dense before, like suggested on the website that was linked in this thread. If its mass didn't change significantly over time, but only its density became lower and its size became bigger at the same time, wouldn't gravity be reduced in the process? That would imply that this theory can possibly be checked. Is there any way to determine Earth's gravity in the past?

by **goredsox** » Tue Sep 25, 2007 11:35 pm

It sure would be interesting to compare seismic records and tectonics from another planet about the size of Earth without a moon...
...say Venus for example

Yeah, I agree.......

Am I correct in stating the our Moon is the only Moon in the Solar System that is thought to have formed from a collision, rather than from a capture of an asteroid or a comet?

Also it would seem that tectonic movements on Earth are unique for other reasons too, such as the unique balance of mantle temperature and crust temperature, planet density, the gravitational mass, and so on. One is hard pressed to come up with another body in the solar system with anything like our tectonics. Maybe Io, and the shared factor may be the intense tidal forces of a rapid orbiting relationship (in our case, the moon; in Io's case, Jupiter).

by **Andy Wade** » Tue Sep 25, 2007 4:45 pm

jimmysnyder wrote:No one is buying my image of the earth tipping over like an egg the day after an equinox? How about a moment of silence for the passing of Marcel Marceau?

Shouldn't that be a moment of noise?

by **jimmysnyder** » Tue Sep 25, 2007 12:05 pm

No one is buying my image of the earth tipping over like an egg the day after an equinox? How about a moment of silence for the passing of Marcel Marceau?

by **auroradude** » Tue Sep 25, 2007 9:51 am

It sure would be interesting to compare seismic records and tectonics from another planet about the size of Earth without a moon...
...say Venus for example.

Starship Asterisk*

Pangea Ultima: Earth in 250 Million Years? (APOD 22 Sep 07)

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