Does destructive interference of an electromagnetic wave create negative energy?

[Quarker]

It’s well known that energy is not lost when destructive interference of an EM wave takes place. The energy of the wave instead moves to areas where constructive interference occurs. Does that mean that the area of destructive interference has negative energy?

 

[renormalize]

It’s well known that energy is not lost when destructive interference of an EM wave takes place. The energy of the wave instead moves to areas where constructive interference occurs. Does that mean that the area of destructive interference has negative energy?

No, the energy-density of an EM wave is non-negative definite. The lowest value possible for EM energy-density is zero.

 

[Baluncore]

Does that mean that the area of destructive interference has negative energy?

No.
The magnitude of the sum of two unit vectors, with a phase difference, will vary between 0 and 2.
Destructive interference is close to zero energy.
Constructive interference is close to double energy.

 

[Quarker]

How has this been proven experimentally, aside from the conservation of energy argument?

 

[Baluncore]

How has this been proven experimentally, aside from the conservation of energy argument?

Phased antenna arrays are designed to reinforce signals from the wanted directions, and to cancel signals from unwanted directions.

You must be careful with measurements of interference, because when you introduce a sensor, it will disturb the interference pattern and energy distribution.

 

[Dale]

As @Baluncore mentioned phased array antennas work on this principle. Probably the most demanding application is synthetic aperture radar. This allows a radar to literally steer a beam of radar across an area using constructive and destructive interference between the different elements of a phased array radar.

 

[Quarker]

Phased antenna arrays are designed to reinforce signals from the wanted directions, and to cancel signals from unwanted directions.

You must be careful with measurements of interference, because when you introduce a sensor, it will disturb the interference pattern and energy distribution.

Is the array sensitive enough to detect any slight variations of energy that may imply the existence of dark energy? A steady state EM wave obeys the law of conservation of energy, but how has it been proven that destructive interference doesn’t create negative energy, which would still conserve energy if balanced by more energy in the areas of constructive interference? It doesn’t seem like this possibility is taken into consideration. Negative energy would have major implications for the standard model. It seems odd that the possibility has never been experimentally ruled out.

 

[Dale]

Is the array sensitive enough to detect any slight variations of energy that may imply the existence of dark energy?

It is always possible to hypothesize the existence of an effect so small that it cannot be detected. So no experiment can ever rule out “any slight …”. All we can ever say is that if there is such an effect it is negligible in any experiment to date.

Negative energy would have major implications for the standard model.

How so? Binding energies are already negative, as is gravitational energy, and the Casimir effect. Do you have a peer reviewed paper that explains this “major implication”? I personally don’t see it.

 

[weirdoguy]

It doesn’t seem like this possibility is taken into consideration.

With all due respect, negative energies appear already at high-school level physics, so if you don't know that then I don't think you should waste your time on fantasizing about new undiscovered physics. Learn the basics first.

 

[Quarker]

It is always possible to hypothesize the existence of an effect so small that it cannot be detected. So no experiment can ever rule out “any slight …”. All we can ever say is that if there is such an effect it is negligible in any experiment to date.

How so? Binding energies are already negative, as is gravitational energy, and the Casimir effect. Do you have a peer reviewed paper that explains this “major implication”? I personally don’t see it.

Because theory says that the energy created by destructive interference should be zero.

 

[Dale]

Because theory says that the energy created by destructive interference should be zero.

Sure, but you were claiming it “would have major implications”. Please provide a professional scientific source that describes said “major implications”.

 

[Quarker]

Sure, but you were claiming it “would have major implications”. Please provide a professional scientific source that describes said “major implications”.

I’m not going to speculate about something that hasn’t been detected yet. If there is a negative energy associated with areas of destructive interference, people may not agree on where that negative energy comes from.

 

[renormalize]

I’m not going to speculate about something that hasn’t been detected yet.

Yet you said earlier:

Negative energy would have major implications for the standard model.

How can that statement be anything other than a personal speculation since you've offered absolutely no outside references to support it?

 

[weirdoguy]

If there is a negative energy associated with areas of destructive interference, people may not agree on where that negative energy comes from.

How about this:

Learn the basics first.

?

If there are pink unicorns ruling whole universe, people may not agree on the shade of the pink they have. Personally, I don't belive in pink, everything is black.

 

[Ibix]

A steady state EM wave obeys the law of conservation of energy,

Does it? How do you know?

The same issues arise with all EM waves. The theory says that they all respect conservation of energy but experimental verification of this only has so much precision, and this is true whether there's interference or not. And since you can Fourier decompose anything except a perfect eternal sine wave into components that produce the observed wave form by interfering, every wave can be seen as a product of interference. So it's not clear to me that the distinction you think you are making between a "steady state EM wave" and destructive interference is at all meaningful.

Essentially you are asking if the theory could be an imperfect description of reality. Sure it could, but that's true of literally any theory so the answer tells you nothing. Instead, you can ask to what precision some claim (e.g. "EM respects energy conservation") has been tested, but often the answer will be "hard to say". Some aspects of EM theory have been tested to absurd precision (e.g. tests of Gauss' law, which impose constraints on a hypothetical photon mass of ten to the minus fifty-something kilograms), and that imposes constraints on what an alternative EM-theory can look like. But to what extent it constrains energy conservation violation in every circumstance I'm not sure.

Fundamentally, if you want to suggest that EM doesn't obey mainstream theory you need to propose a new theory (not here, obviously). That's because, as above, wondering if the mainstream theory is exactly matched by experiment is a waste of time. When you propose a new theory it is possible to use it to make predictions like "energy conservation is violated by one part in a million if you do experiment A and two parts in a million if you do experiment B". Then (if you can convince scientists your work is worth testing and it isn't already ruled out due to its predictions on experiment C that we've already done) we can see if we can do A and B to the necessary precision. Otherwise, if you don't have a theory, you end up with an endless game of "maybe energy conservation is violated by a slightly smaller amount than the minimum we can detect... Oh, we've improved our precision? Well, how about just smaller than that?" Rinse and repeat.

 

[sophiecentaur]

I’m not going to speculate about something that hasn’t been detected yet. If there is a negative energy associated with areas of destructive interference, people may not agree on where that negative energy comes from.

There are many examples of negative and positive potential energy; it can be when describing attractive and repulsive forces or when describing the change in gravitational energy change when moving from the surface of one planet and another. To simplify matters, gravitational potential energy is described relative to 'infinity' and this gives negative values everywhere (nicely consistent but arbitrary).

Trying to associate these ideas with 'negative' or 'dark' energy and what happens during diffraction of waves is pretty nonsensical. The point about learning the basics first has already been made but Science is not magic.