# Could dark matter be like ether?

Could dark matter (and dark energy) be proven wrong as ether was? Is it possible that we actually misunderstand how gravitation works, and that our current model is wrong? The fact that we need an invisible matter to make the laws of physics work looks like what we've done with ether. Since the laws of physics don't seem to work at microscopic scale or galaxy scale (or at least we need different laws), is it possible that they happen to work at our scale because that's the one in which we were when creating them?

Yes, it's possible and there exist papers that claim to explain many effects normally attributed to dark matter to other parts of new physics like MOND – the Modified Newtonian Gravity. They either add new fields and new local interactions or completely nonlocal interactions, or perhaps try to link these novelties with the holographic principle or other interesting ideas in physics.

But physicists usually think that all these alternative models are heavily disfavored. Some observations of dark matter's motion seem "almost direct". In general places of the cosmos, the dark matter seems pretty much "independent" from the visible one, and so on.

Equally importantly, physicists mostly don't share your (and others') preconception that there's something wrong about dark matter – that it's a new artificial addition one should normally not expect. Dark matter is just some matter that isn't easy to see through electromagnetic radiation. There's nothing artificial about it. Indeed, it would be unnatural to think that all forms of matter may be pretty much visible by the same technology/field that is used in our eyes.

If the electric charge of new particles is zero, their interactions with the electromagnetic field is highly reduced. And theories exist that naturally predict, in some cases, whole sectors of particles uncharged under the electric field but charged otherwise, and so on.

Some particular classes of dark matter may be ruled out or disfavored, perhaps even neutralino-like WIMP may be getting to that stage. But there are others that remain viable, axions, gravitinos, and so on. Physics would only move towards your alternative theories if there were some new evidence – e.g. some independent measurement of deviations from the Newton's gravitational law. I think it's very unlikely which means that it's very probable that non-dark matter theories of similar phenomena will be considered fringe theories for years to come. And they may get killed almost completely by a discovery of some details about the composition of dark matter.

There are suggestions for ways to explain the observed redshift without dark energy. One example is the suggestion that the redshift is related to light undergoing redshift as it passes through matter that is not distributed homogeneously.

You say that the laws of physics don't work at the microscopic scale. This is false. Systems at the microscopic scale can often be described with high accuracy by classical continuum mechanics since a system of size $10^{-6}$m is large compared to the scale of single atoms ~$10^{-10}$m. And in cases where that doesn't work, quantum mechanics can be used to describe and explain what is happening. So the laws of physics work quite well at the microscopic scale.

In cases where we don't understand the laws of physics, the regimes in which they are not understood are characterised in a more complicated way than just looking at the size of objects. For example, we don't understand what happens in black holes, but black holes can vary a lot in size, depending on their mass. A black hole the mass of the sun would be about 3km in radius. A black hole of 4 million solar masses would have a radius of about 12 million km.