# Is Earths' potential of 0 volts valid throught the Universe?

• B
• Bill Hendry
In summary, the Earth's voltage is not absolute but relative. It is calculatable and relevant for most applications.
Bill Hendry
We have set the Earths' Voltage at zero volts but is this 'earth voltage' applicable throughout the Universe. If not, is it relative in the same manner as spacetime and is it calculatable?

Hello Bill,

Do 'We' have a reference for our claim ? In various contexts your statement "We have set the Earths' Voltage at zero" can mean different things.

Bill Hendry said:
We have set the Earths' Voltage at zero volts but is this 'earth voltage' applicable throughout the Universe. If not, is it relative in the same manner as spacetime and is it calculatable?
For most applications, the choice of which voltage to choose to be zero is a convention rather than a fundamental fact about reality. It's less that the Earth has a voltage of zero, but rather that it has a consistent voltage that we can rely upon. When doing calculations for how most electric systems operate, you can add a constant voltage to every component in the system and its behavior will not change one iota. You could easily say, "The Earth's voltage is 3V," and pretty much nothing would change.

It's differences in voltage that are meaningful (again: most of the time), not the absolute value. If you pick up a 1.5V battery, for instance, that voltage isn't the "voltage value of the battery". Rather, it's the difference in voltage between the + and - terminals. That voltage difference is maintained by the chemical behavior of the materials inside the battery. The absolute voltage of either terminal will be determined by its environment. For example, if you take two 1.5V batteries and place them end-to-end (with + of one battery contacting - of the other), then the voltage differences add, such that the voltage difference from the - of the first battery to the + of the second is now 3V.

This is, in fact, how many 9V batteries are constructed: they're a set of six AAAA batteries with their terminals connected in series.

Caveat:
You may notice that I left open the possibility that some things might depend upon the absolute voltage. It's unfortunately been way too long since my electrodynamics course, but I do recall that the absolute value makes a difference in some contexts. But I also remember very distinctly that this is extremely obscure and not relevant 99.999% of the time.

A possible interpretation of the question is "is Earth potential the same as Mars potential"? Or Vulcan potential, or whatever your favourite extra-solar planet is. I think the answer to that is yes, because otherwise we'd see electric fields in space affecting the solar wind.

Ibix said:
A possible interpretation of the question is "is Earth potential the same as Mars potential"? Or Vulcan potential, or whatever your favourite extra-solar planet is. I think the answer to that is yes, because otherwise we'd see electric fields in space affecting the solar wind.
My bet is that there is some potential here caused by the solar wind. It will be pretty small, however.

kimbyd said:
My bet is that there is some potential here caused by the solar wind. It will be pretty small, however.
I thought about that, but the solar wind must be electrically neutral overall otherwise the Sun would accumulate a charge. I guess local charge density can fluctuate, which might induce small time-varying potential differences, I suppose?

Ibix said:
I thought about that, but the solar wind must be electrically neutral overall otherwise the Sun would accumulate a charge. I guess local charge density can fluctuate, which might induce small time-varying potential differences, I suppose?
The Sun likely has accumulated a (small) charge due to the fact that electrons and protons have different masses.

And yes, I'm sure the solar wind overall is electrically-neutral (since the Sun won't keep accumulating its charge: it should be a constant). But I expect the Earth may experience something similar due to the different masses. It'll be small, though.

@Bill Hendry : your question gave rise to a whole lot of comments. What this what you expected ?

## 1. What is Earth's potential of 0 volts and why is it important?

Earth's potential of 0 volts refers to its electrical potential energy, which is the amount of energy required to move an electric charge from one point to another. It is important because it helps us understand the electrical properties of Earth and its interactions with other celestial bodies in the Universe.

## 2. Is Earth's potential of 0 volts unique to our planet?

No, Earth's potential of 0 volts is not unique to our planet. It is a fundamental property of all objects in the Universe that have a surface and an atmosphere, including other planets, moons, and even stars.

## 3. How is Earth's potential of 0 volts measured?

Earth's potential of 0 volts is measured by using a device called an electrometer, which can detect and measure the electric potential difference between two points on Earth's surface. The measurement is typically taken at sea level, where the potential is closest to 0 volts.

## 4. Can Earth's potential of 0 volts change?

Yes, Earth's potential of 0 volts can change due to various factors such as atmospheric conditions, geological activity, and solar activity. For example, lightning strikes and volcanic eruptions can temporarily alter Earth's potential, but it usually returns to 0 volts soon after.

## 5. How does Earth's potential of 0 volts compare to other celestial bodies in the Universe?

Earth's potential of 0 volts is relatively low compared to other celestial bodies, such as Jupiter and Saturn, which have much higher electrical potentials. This is because their larger size and stronger gravity result in a higher electric field and potential. However, Earth's potential is still significant in understanding the electrical properties of the Universe.

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