What is Negative energy: Definition and 91 Discussions

Negative energy is a concept used in physics to explain the nature of certain fields, including the gravitational field and various quantum field effects.
In more speculative theories, negative energy is involved in time travel to the past, creation of artificial wormholes, which may also allow for time travel, Krasnikov tubes, Alcubierre drive, and potentially other types of warp drives for faster-than-light space travel.

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  1. A

    Dark energy <=> negative energy?

    Sorry if this sounds a bit mixed up. When I was growing up, in the late 1990's, popular science books about cosmology use to describe the average mass-energy density of the universe, especially comparing it to the critical density. Those books used to say that visible matter gives too-low...
  2. N

    Exploring Negative Energy: What Makes It So?

    can a matter have negative energy? or more appropriately what makes some energy as negative?
  3. N

    May I suggest an experiment concerning negative energy?

    Sometimes to understand things I need to come up with ideas and have them shot down. This is what I am doing here. I have been informed that the Cashmeir effect may not be due to negative energy so I have an idea for an additional experiment. Suppose we were to make a "box" with little...
  4. N

    How much negative energy is that space between two non-conducting plates?

    The negative pressure generated in the Cashmeir effect suggest that negative energy can exist in small spaces between non-conducting plates. How much negative energy exist in a given amount of space as measured in units that refer to energy (as opposed to units of force created by the Cashmeir...
  5. J

    External Fields and Negative Energy Transitions In Dirac Particle

    Homework Statement Suppose a relativistic particle with spin 1/2 at rest. Show that if we apply an electrical field at t=0 there's a probability fot t>0 of finding the particle in a negative energy state if such negative energy states are assumed to be originally empty. Homework Equations...
  6. F

    Calculate kw from positve and negative energy totals

    Hi can anyone tell me if I had the following readings how could I calculate kw or kwh. The readings were taken from an electricity meter which logged the values every 15 minutes and the values below are what were recorded in the first 15 minute period; A+ Energy Total = 3920Wh A- Energy...
  7. P

    Dirac's explanation of negative energy states

    I wonder whether Dirac explanation of paradox of negative energy solutions of his equation is viable. Of course this paradox is absent in QFT but if we treat Dirac equation as an equation for wave function of electron the negative energy solution are a puzzle. Acording to Dirac we don't...
  8. B

    Physics Lab: Negative Energy Loss on Roller-Coaster Track

    Homework Statement We recently did a lab in my physics class where we looked at the conservation of energy of a ball on a roller-coaster track. We got the data as seen in the picture below http://tinypic.com/r/168zx2s/7 the question now is why is there negative energy loss, is this...
  9. nomadreid

    Particles in a negative energy region?

    This question is unsourced and hence may be wiped out as hearsay, but perhaps some kind person might answer anyway. I remember (but cannot find the original source) that I once read a speculation that a "particle with negative energy" (not referring to anti-matter, but some sort of exotic...
  10. nomadreid

    Antimatter and negative energy

    In his popular-physics book "The Universe in a Nutshell", Hawking presents the creation/annihilation of virtual particle pairs in two ways: (1) one particle has positive energy, the other negative energy, and (2) a matter/antimatter pair. This leads to the obvious conclusion that he is...
  11. G

    Negative Energy in Newtonian Mechanics: Explained

    Actually i never got this concept clearly in my mind. What is the meaning whern we say that the energy of a body is negative? For example in Bhor's atomic model we have calulated the total energy of an electron to be negative. Please explain me by using Newtonian Mechaincs as i am the...
  12. J

    How Do Particles with Negative Energy Contribute to Hawking Radiation?

    can someone please try to explain to me how a particle can have negative energy - specifically how one particle from spontaneous particle pair production near a BH EH can (must) have negative energy as it falls into the BH resulting in hawking radiation? i am now trying to accept that...
  13. S

    Negative Energy of Bound Bodies & Hydrogen Atom

    What is meant by total negative energy associated with bound bodies like planets. and also total energy of the hydrogen atom is negative. I wonder how it could be? Because I believe whatever negative energy may be, It must only be associated with bound systems, and I don't think that an isolated...
  14. T

    Negative energy photon emission

    Let's say we just had a normal atom in energy state E, and one of the electrons jumps down to a lower orbital E'. Of course, E - E' is positive because E' is a lower orbital than E, so the energy of the photon emitted must be positive. But what if E' were a higher orbital than E? Could the...
  15. maverick280857

    Exploring the Meaning of Positive and Negative Energy in the Klein Gordon Field

    Hi everyone The Hamiltonian of the Klein Gordon field can be written as H = \frac{1}{2}\int d^{3}E_p \left[a^{\dagger}(p)a(p) + a(p)a^{\dagger}(p)\right] and we have [H,a(p')] = -E_{p'}a(p') [H,a(p')] = +E_{p'}a^{\dagger}(p') The book I'm reading states that What does this mean? Thanks.
  16. R

    Negative Energy Solutions to Photon Wavefunction

    Hello: My question is simple: Does not the standard differential wave equation from Maxwell's relations lead to both positive and negative energy solutions for a photon's E field? If so, then why do we always throw away the negative energy solutions? Is this just custom? I suspect it is...
  17. S

    The Alcubierre Drive and Negative Energy

    My understanding of the Alcubierre drive is that a spacecraft is encompassed within a 'bubble' of expanding spacetime (at rear of craft) and contracting spacetime (at the front). I am trying to understand the role of negative energy in this scheme. Am I correct in saying that the...
  18. S

    Status of Gravity & Net Energy of Universe: Is Theory Viable?

    I want to know what the status of gravity constituting "negative energy" is. This theory proposes that the net energy of the universe is zero, presumably with the electro-weak and strong forces exerting "positive" energy over their respective ranges (distance). Is this idea still viable?
  19. F

    Negative energy in Dirac theory

    Can anyone explain what's negative energy mean in Dirac theory? Does it imply anti-particle travel backward in time?
  20. U

    Quantum Fluctuations of Negative Energy

    It is my understanding that quantum fluctuations arise from implications of the Uncertainty Principle. Specifically: http://upload.wikimedia.org/math/b/d/1/bd1bb25a5159f9c74803afca6ad65935.png And that this means that conservation of energy can appear to be violated for a set time "T."...
  21. M

    Quantifying Negative Energy from Entropy

    Entropy has an associated energy quantity that has negative pressure (cosmologically... spacetime). How does one calculate the quantity of this (negative?) energy from the entropy? Given that an event horizon has maximal entropy, would this produce significant repulsion? Anyway, I'd...
  22. H

    Negative energy solutions - Dirac equation

    The http://en.wikipedia.org/wiki/Dirac_equation" , which itself is based upon the relativistic energy-momentum relation E^2 = p^2 + m^2 (natural units). And here comes my question then: Why do we throw away the negative energy solutions in relativity but do we keep them when we combine it...
  23. G

    [Q]eigenfunction of position operator and negative energy

    Hi, Everybody know that eigenfunction of position operator x' is \delta(x-x') But i also knew that integral of square of current state over entire space is 1(probability) Then, \int_{-\infty}^{\infty}\delta(x-x')\delta(x-x')^{*} dx is 1? What is conjugate of \delta(x-x') ...
  24. K

    Feynman's perspective on negative energy states and pair creation

    Dirac's theory of the electron predicted that there were identical particles of equal mass but of negative energy. He appealed to the Pauli exclusion principle and proposed that there was a negative energy 'sea' of electrons that was full up to -2mc^2 in order to answer critics that positive...
  25. K

    Negative energy in Dirac equation

    When Dirac solved his equation for electron, he found out there are negative energy states. My question is why electrons won't jump from positive energy state to negative energy states and release energy as photon? Dirac proposed that all negative energy states have been filled so electrons...
  26. S

    Solving Shrodinger Eqn for Constrained System: Negative Energy Levels?

    If we solve the shrodinger equation for a constrained system we will find some negative energy levels.The nagative sign shows that this energy is released and no longer exist in the system. Then how we can say the system is in this level with this ENERGY? are we talking about something that...
  27. A

    Unveiling the Mystery of Negative Energy and Transportation

    negative force! can anyone in this world,tell me what is negative energy... how does that help in transportation... heard that if it really existed,we can travel large distances in few seconds please do help folks
  28. C

    How Can You Have Negative Energy in a Positive Potential?

    so I am studying the delta potential now and I notice that griffiths defines scattering and bound states as cases where E>0 and E<0 respectively. but I have to ask if you have a positive potential, then how an you have negative energy?
  29. D

    Is the Energy of the Universe Really Zero?

    I read that the energy of the entire universe might be zero, by an argumnet of the positive energy matter content balanced by the negative gravitational potential energy (see e.g. ttp://www.astrosociety.org/pubs/mercury/31_02/nothing.html). How does this argument go from a GR point of view...
  30. Z

    On explanation of negative energy states and electron pair creation

    Dirac's theory of the electron predicted that there were identical particles of equal mass but of negative energy. He appealed to the Pauli exclusion principle and proposed that there was a negative energy 'sea' of electrons that was full up to -2mc^2 in order to answer critics that positive...
  31. D

    Exploring the Analogy of Negative Energy in Physics: The Jack-in-the-Box Example

    I seem to recall reading an analogy describing the total mass/energy of a jack-in-the-box. This said that a compressed spring insided a box would "weigh" more than the same when relaxed (albeit immeasurable small). This makes sense given the equivalence of energy and mass. But what if the spring...
  32. A

    Gravitational waves and negative energy.

    I was wondering what's the link between gravitational waves and negative energy, i heard that 'in the presence of large gravitational fields, negative energy fields are rather common' from one of michio kaku's book. what's the link between gravitational fields and gravitational waves/ gravity...
  33. H

    Negative energy versus positive energy

    Cancellation or generation of positive energy by negative energy and vice versa is so often brought up by very serious physicists (e.g. A. Guth, A.V. Fillipenko) as the argumentation for the possibility of the generation of our universe out of “nothing”, that I hardly dare to question this. As...
  34. L

    Can Negative Energy Theoretically Enable Faster-Than-Light Travel in Sci-Fi?

    I know crazy unsupported theories aren't supposed to be posted, but I have been working on some fiction which requires faster than light travel. I have read many other guides to ftl in SciFi, and I had origionally fitted in a form of hyperdrive, which would simply avoid the issue by ignoring the...
  35. P

    What Force Did Dirac Envision for Negative Energy States in His Theory?

    In every situation I'm aware of, energy states exist because of some force that gives rise to them (dE/dx, y'know). What force did Dirac envision as giving rise to his proposed negative energy states (from which antimatter arises)? When I see it described in textbooks, the states are shown as...
  36. A

    Is Negative Energy Possible in the Bohr Model?

    in the bohr model, the electron is in constant motion. how can such an electron have a negative amount of energy? p.s. sorry for clogging up this area with so many questions... I've been having a hard time understanding this area~
  37. W

    Exploring the Casimir Effect: Negative Energy

    Ummm...I don't know if this is the best section for this... but... it is said that a negetive energy can be created through the quantum theory via the Casimir Effect. Here is what I know as fact. In 1948, a Dutch physicist known as Henrik Casimir discovered how this negative energy can be...
  38. T

    Negative Energy in Quantum Theory: A Puzzling Problem

    In the transition from "basic" quantum theory to quantum field theory, both in the derivation of the Gordon-Klein and of the Dirac-equations, there is a big problem with solutions with negative energies. Can anyone explain me why this is being considered a big problem in the first place (it...
  39. C

    Negative energy and opposite self-induction device

    Hello. Take a look to this page: www.geocities.com/nayado/ You all know that in a normal induction process, a back-emf is generated that tends to oppose current flow. All our motors, generators and devices work like this: You introduce a flow or movement, and the device operation will...
  40. H

    Negative energy density in a Casimir vacuum

    I have read often that the vacuum energy density in a Casimir vacuum is negative, but I do not understand this. My understanding is the following. The Hamiltonian can be written as a sum over all spatial modes. Calculating the energy density for the vacuum state H|0> = ∫dV ρ_o |0>, leaves...
  41. E

    Exploring Froth Flotation & Negative Energy of Activation

    does anyone here has any idea what is froth flotation(in extraction pf metals) and negative energy of activation( as in chemical energetics)? thanks for any input.
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