Please explain negative energy or I will kill myself.
- Adam
No, seriously. What’s the deal with negative energy? Does it exist in forms like positive energy (heat, electricity, light, etc.)? Does something get hotter or colder as it increases negative heat? How can you have negative light? Thanks.
- Adam
Oh, boy!
Another “Talk to Myself on the SDMB Thread”!
Seriously, though…
How can you be sure that you won’t kill yourself after negative energy is explained to you?
Google is your friend, too!
Part of it is how you want to define zero. In gravitational and electrostatic terms, zero is typically defined when two objects are infinitely far apart, so potential energy for an attractive force is negative. That way, it’s easy to compare if the kinetic energy is smaller in magnatude, so there is no way for they system to spontaneously separate. It’s a bound system if the sum is negative.
Negative energy is just like positive energy, except that it heals undead instead of harming them.
To take swansont’s explanation and run with it, I present a short explanation of several forms of negative energy:
Kinetic = 1/2 * mass * velocity^2, and therefore cannot be less than zero
Local gravitational potential = mass * local gravitational acceleration * difference in height between current location and the location to which we wish to move it. If the object is above where we wish it to be, we can drop it and it will go there on its own, because it has positive energy. If the object is below where we want it to be, we say that it has “negative” energy, meaning that we’re going to need to find some energy somewhere else to move it. One caution: the local gravitational acceleration is actually a vector, and usually assumed to be a negative, so your height difference also needs to change signs.
Heat energy can be expressed a number of ways, but in scientific discourse, you usually end up using Kelvin (or Rankine, ugh!) to measure the absolute temperature of the object. These scales differ from your normal C and F scales in that their zero-point is “absolute zero” and there’s no way to get an object colder than zero. Expressed in this way, there is no such thing as negative thermal energy. When you think something is “cold” you really mean that it has less thermal energy than your reference point.
Negative energy is also what I feel when I see people leaving total downer answers to a really cosmic, open question.
Jurph, you total clod.
The OP clearly specified “light” and “electricity” as forms of negative energy he was interested in. If you can’t be arsed to read the OP and the OP’s response to his own post, you need to not be staying out so late.
Light energy can’t be negative, either–no light is just “dark”. You could re-do all the math and physics replacing photons with “darkons” and heat with coldness, and IIRC, you get some interesting side effects like a maximum amount of “cold energy” something can contain, or the maximum amount of “darkons” an object can be radiating.
That’s just another way of saying that you’re redefining what zero energy is. As you point out, you could redefine heat and light in terms of cold and dark. But in those system I think some problems come up when, instead of terms going to zero, they become infinite. (e.g. no light would have to be an infinite number of darkons) Zeroes are often easier to deal with. (dark = zero photons)
One of the reasons that there are perpetual motion charlatans about, who want to tap into vacuum energy, is that some solutions are actually infinite, so it’s assumed that an infinite amount of energy is available. But physicists ignore the infinite term (because it’s meaningless) and look at the rest of the answer, which has physical relevance.
Positive vs. negative energy can be viewed in a similar fashion - it’s just a matter of what gives a useful answer and makes the math easier. Unless you’re talking about science fiction, where it can mean anything you want.
Okay, to sum up what I am understanding:
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Everything’s relative. Negative energy is really negative negative energy, right? If I have zero light photons, I have an infinite number of darkons, but there’s no real reason to measure lack of light (especially infinite lack of light), so we simply measure the available positive light.
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Negative energy is used to describe the need for energy. Since negative energy could be considered levitational instead of gravitational, a steel beam is using x amount of negative energy to remain not a part of a building. Conversely, the steel beam would require y amount of energy to become a part of the building. Therefore, *y = *|x|. Could this be considered a factor in entropy?
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Finally, in the case of wormholes (my real reason behind the thread), are scientists arguing that negative energy is needed for wormholes to exist because the amount of energy needed to open a wormhole is infinite? I’m still a little hazy on this.
Thanks to everyone who seriously answered my post, even with a wacky starting topic.
- Adam
Correction: *y = *|x| when *y != *0.
Right?
Some of the above responses illustrate why the total energy of the universe is zero. All the positive energy due to matter and radiation is exactly offset by negative gravitational energy.
So you could say that the creation of the universe via the big bang was the creation of nothing from nothing.
Negative energy (exotic matter, the energy density between Casimir plates etc.) is gravitationally repulsive and it’s necessary to both keep the wormhole open and to defocus light rays as they exit the hole.
Negative energy is what is left over when running an over unity machine.
“Beware of the Cog”