Discussion forum > General Discussion
Minecraft Science: Mass of the Minecraft Earth
mcoon1:
First off, you can's start assuming that the measured constants of our universe would be the same in the minecraft universe. For instance: g=9.816m/s^2 on earth... but (as you noted) you can't assume that this would be the same on any planet! In the same way, you couldn't assume that G would be the same as in this universe. The reason that we have a value for G in the first place is because we conducted experiments in physics to determine it. You'd have to do the same for the Minecraft universe.
Even if we assume that G is the same in this universe, you have used the wrong equations. For instance, you are using equations for gravity that require the Minecraft earth to be spherical. In reality, you very easily could have used Gaussian physics OR Newtonian physics and advanced calculus to show that the vector for gravity on a (relatively) infinite, flat plane is perpendicular to the surface, downward, and equal to 2*pi*G*p*H, where pi=3.1415..., p is the average density of the the object per unit, and H is the thickness of the object. From this, you would get a very accurate value for g. However, even with this, since the Minecraft world could, in theory, expand infinitely outward, you can't use this value to calculate the mass of ME.
If you ask me, in order for the minecraft universe's physics to make sense, there must be a super dense (probably neutron star material-esk) layer of material a few hundred blocks below the layer of bedrock to account for the gravity. This makes sense, since it's density would make it absorb light, explaining the darkness below the map. Also, it would explain why the player dies when they pass to a certain depth below the map (spagetification).
RuthlessTomato:
You need to show this to your teachers.
Wyboth:
--- Quote from: DJAlphaWolf on February 06, 2013, 05:24:36 am ---Awesome. Thanks wy!
The PE and KE equations made sense.
Now is it possible to determine if the planet orbits? I know we are given the length of a minecraft day to a year on the wiki. But how fast does the minecraft earth orbit, if at all?
Can we calculate axial tilt, if any?
Is it possible to translate the intensity of the sunlight equipped with the biome its in, into temperature? I doubt this is possible. But how awesome would it be if we could do it.
--- End quote ---
We know the ME orbits its star, but it would be impossible to determine its orbital period. The star has no perigee or apogee, and the ecliptic's altitude does not change. The only conclusions we can draw from this are that the ME's orbit around its star is circular, and that its axis is pendicular to its plane of orbit.
It might be possible to translate luminosity into temperature, but our current laws would not work for this, since they rely on the inverse square law, where in Minecraft light decays linearly.
Mcoon, I will respond to you in a bit. I'm out of time right now.
mcoon1:
Let me point something else out:
We can calculate the average density of ME using Gausse's laws:
g = (2*pi*G)*p*H (m/sec^2)
g = (4.19338524e-10) * p * H (m/sec^2)
g = (4.19338524e-10) * p * (64) (m/sec^2)
g = (2.68376655e-8) * p (m/sec^2)
(14.4622) (m/sec^2) = (2.68376655e-8) * p (m/sec^2)
p = 538876974.251 Kg / m^3
p = 538876.974 g / cm^3
This means that, on average, ME has to be 27935.56 times as dense as gold (p = 19.29 g/cm^3).
For estimation purposes, we can guess that the average density of minecraft blocks is arround 2 g/cm^3 (water = 1g/cm^3, dirt = 1.22 g/cm^3, stone (granite) = 2.75 g/cm^c). With this approximation, we are accounting for only 0.0000051032% of what it should be.
This means that there MUST be something located below the bedrock layers from 0-4 that is creating the gravity on ME. As I stated earlier, a layer of superdense material located a hundred blocks below the bottom map-layer would do the trick.
The cool thing to note about this would be that, with such a high mass and density, ME's sun would actually orbit it, much like the ancient astonomers thought about the earth-sun system!
Wyboth:
Firstly, I would like to note that the paper has been updated. I had used the distance from the origin to the edge of the world as the radius before. In reality, this is half of the circumference. I have applied these changes. The correct mass is 1.924 * 1025kg. The acceleration was not affected.
Now, I will respond to Mcoon.
--- Quote from: mcoon1 on February 06, 2013, 07:10:31 am ---First off, you can's start assuming that the measured constants of our universe would be the same in the minecraft universe. For instance: g=9.816m/s^2 on earth... but (as you noted) you can't assume that this would be the same on any planet! In the same way, you couldn't assume that G would be the same as in this universe. The reason that we have a value for G in the first place is because we conducted experiments in physics to determine it. You'd have to do the same for the Minecraft universe.
Even if we assume that G is the same in this universe, you have used the wrong equations. For instance, you are using equations for gravity that require the Minecraft earth to be spherical. In reality, you very easily could have used Gaussian physics OR Newtonian physics and advanced calculus to show that the vector for gravity on a (relatively) infinite, flat plane is perpendicular to the surface, downward, and equal to 2*pi*G*p*H, where pi=3.1415..., p is the average density of the the object per unit, and H is the thickness of the object. From this, you would get a very accurate value for g. However, even with this, since the Minecraft world could, in theory, expand infinitely outward, you can't use this value to calculate the mass of ME.
If you ask me, in order for the minecraft universe's physics to make sense, there must be a super dense (probably neutron star material-esk) layer of material a few hundred blocks below the layer of bedrock to account for the gravity. This makes sense, since it's density would make it absorb light, explaining the darkness below the map. Also, it would explain why the player dies when they pass to a certain depth below the map (spagetification).
--- End quote ---
You are correct in saying that g differs between planets, as it is dependent on mass and radius. However, in our universe, G is a constant. I see no reason why we shouldn't assume that G is the same in the Minecraft universe, and since we cannot replicate Candevish's experiment, we really have no other choice.
Now, for Gauss's equation. g=2piGpH would give you the density of the ME, not the mass. I was specifically looking for mass. The reason why I didn't use this is because you could not accurately calculate the volume of the ME, since there are varying heights, air pockets in caves, etc. etc. etc. If we did know the exact volume of the ME, we could determine an accurate mass. But, since we lack this number, we cannot use Gauss's law to calculate mass.
The alternative is this. However, this is for a planet where it is as tall as it is wide, and a planet where Fg does not always point in the negative y direction. So it would not be accurate for Minecraft either.
Also, I would like to use Gauss's law for Earth.
g=(2*pi*G)pH
9.81=(2*3.141592654*6.67e-11)p*6378100
9.81=0.002672988p
p=3670.05 kg/m3
p=36700.5 g/cm3
By this calculation, the Earth is, on average, 1,902.566 times as dense as gold. Obviously something is wrong here.
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