Why It Must Be a Solid
A fluid cannot carry a transverse wave. Light is transverse. The conclusion is unavoidable and it is the oldest difficulty in the subject.
Draft. This memo is a working draft, published for scrutiny rather than as a settled result. Figures, derivations and conclusions are open to revision, and the ledger at the foot records what is derived, what is measured, what is assumed and what remains unanswered. Where a number is carried from a secondary source and not verified against the original, the sources section says so.
The TOE series supersedes the earlier A Classical Aether Model and Governor Atom Model white papers one memo at a time. Where this memo and those papers disagree, this memo is the later position.
Proven in this memo
- The medium carrying light has a non-zero shear modulus, and is therefore a solid rather than a fluid. This follows from polarisation alone.
The resolution of the drag objection in section 5 is an argument, not a proof: it depends on the ruling that matter is clumped Aether, which is assumed here and argued in memo 2.1.
In plain terms
Shake one end of a rope and the wave travels along it while the rope itself moves up and down — across the direction of travel. Push one end of a rod instead and the wave is a squeeze running along it, with the material moving the same way the wave goes.
The first kind only happens in something rigid. Air, water and every other fluid can carry the squeeze but not the shake, because a fluid has nothing to grip sideways with. Slide one layer of water past another and it simply slides; nothing pulls it back.
Light is the shake, not the squeeze — that is what polarised sunglasses are exploiting. So whatever carries light has to be able to grip sideways, which makes it a solid rather than a fluid.
That was the classical aether's worst problem. A solid filling all of space, stiff enough to carry light, and yet the planets sail through it without slowing. The answer here is that they do not sail through it. They are made of it.
1. The numbers
- Fluids carry one wave type; solids carry two.
- Light has two independent polarisation states — a compression wave has none.
- Required shear modulus: 8.089 × 1016 Pa, some five orders above steel.
- Earth's orbital decay from drag, over 4.5 billion years: nil observed.
2. Two kinds of wave, and only solids have both
A medium can carry a disturbance in two ways. In a longitudinal wave the material moves along the direction of travel: alternating compression and rarefaction, which is what sound in air is. In a transverse wave the material moves across the direction of travel.
A transverse wave requires the medium to resist shear — to resist one layer sliding past its neighbour. Fluids cannot. Slide one layer of water past another and nothing pulls it back; there is no restoring force, so there is no wave. This is why sound travels through the ocean and through the Earth, but only the Earth carries the S-waves that seismologists use.
3. Light is transverse
Light can be polarised. A polarising filter passes one orientation and blocks the one at right angles to it, which is why two crossed filters pass nothing at all. That requires the wave to have an orientation across its direction of travel.
A compression wave cannot be polarised. Its motion is along its own axis and there is nothing to rotate — sound cannot be polarised, and no filter has ever been built that would try.
ProofThe medium has shear rigidity
Light exhibits polarisation, with two independent states. Only a transverse wave can carry a polarisation state, because a longitudinal wave has no degree of freedom across its axis to carry one.
A transverse wave propagates only in a medium with a non-zero shear modulus, because the restoring force for transverse displacement is the shear stress. Set G to zero in equation (1) and the wave speed goes to zero with it.
Therefore the medium carrying light has G > 0. A medium with shear rigidity is a solid. This is not a modelling choice about the Aether — it is forced by an everyday property of light.
Chain: polarisation → transverse → equation (1) → G > 0. Premise: that light is a wave in a medium at all.
4. How stiff, and why that was the problem
Memo 1.3 fixes the value: G = ρc2 = 8.089 × 1016 Pa. For comparison:
| Material | Shear modulus |
|---|---|
| Rubber | ~106 Pa |
| Aluminium | 2.6 × 1010 Pa |
| Steel | 7.9 × 1010 Pa |
| Diamond | 5.3 × 1011 Pa |
| The Aether | 8.1 × 1016 Pa |
Five orders of magnitude above diamond. This is the objection that sank the classical aether. Space had to be filled with something rigid enough to carry light at 3 × 108 m/s, and the planets had to move through it for billions of years without measurable drag. Maxwell, Kelvin and Lorentz all knew the difficulty and none of them resolved it.
5. The answer, and what it costs
The objection assumes matter moves through the medium. Under the ruling of memo 2.1 it does not: matter is clumped Aether, so a planet is not an object travelling through the lattice but a pattern travelling in it.
The wave, not the water
A wave crossing the ocean travels thousands of kilometres. The water does not. Each parcel of water rises and falls and ends up where it started; what moves is the pattern.
Ask how much drag the wave suffers from the water and the question does not quite make sense — the wave is not passing through the water, it is a shape the water is holding. On this account a planet is the same kind of thing, at a different scale.
That resolves the drag problem, and it is the single strongest reason to adopt the clumped-Aether ruling rather than treating matter and medium as two substances. It is not free. Three costs follow, and two of them are load-bearing elsewhere in the series.
A solid carries a longitudinal wave too. There is no way to have the transverse wave without it, and it necessarily travels faster — √3 c here. That is the subject of memo 1.5.
Rigidity implies a rest frame. A solid has a frame in which it is at rest, and motion relative to it should be detectable. Rotating optical resonator experiments bound Earth's speed through any such frame below about 0.95 m/s, against an orbital speed of 29,800 m/s. This is the most serious unanswered objection to the whole framework and it is the subject of memo 5.7.
The medium must be lossless to an extraordinary degree. Light from the most distant quasars arrives undimmed, and memo 4.2 puts a number on what that requires.
6. What would falsify this
- A demonstration that light is not transverse would remove the requirement entirely. Polarisation has been observed since Bartholin in 1669, so this is not a live prospect.
- Measurable orbital drag on a planet or a spacecraft, beyond what is accounted for by known effects, would falsify the wave-not-water answer in section 5.
- Detection of an aether rest frame above the 0.95 m/s bound would confirm the rigidity and simultaneously overturn special relativity; detection well below it, with improving precision, keeps the objection open indefinitely.
7. Sources
Reference codes read source.work.passage and resolve on the Master Source Register, which carries every source used across this series.
- L. D. Landau & E. M. Lifshitz. Theory of Elasticity, Course of Theoretical Physics Vol. 7. Transverse and longitudinal wave speeds in an isotropic solid, and the requirement that a transverse wave needs a non-zero shear modulus. 75
- J. C. Maxwell. On Physical Lines of Force, Philosophical Magazine Series 4, vols 21 and 23 (1861–62). The wave speed of an elastic medium as the square root of rigidity over density. 79
- S. Herrmann et al. Rotating optical cavity experiment testing Lorentz invariance at the 10−17 level, Physical Review D 80 (2009) 105011. The modern bound on motion relative to a preferred frame, cited in section 5. Volume and page recorded from secondary sources and not verified against the original.
- E. Bartholin. Experimenta crystalli Islandici disdiaclastici (1669). The first observation of double refraction, from which polarisation follows.
Verification register: the Herrmann 2009 citation is carried as reported and has not been checked against the original. The shear moduli in section 4 are standard handbook values and are not individually sourced.
Ledger — memo 1.4
- Derived
- That the medium carrying light has a non-zero shear modulus, and is therefore a solid
- That its shear modulus is five orders of magnitude above diamond
- That the drag objection dissolves if matter is made of the medium rather than moving through it
- Measured
- Light is polarised, with two independent states — observed since 1669
- Speed of light (defined) 72
- Bound on motion relative to a preferred frame, ~0.95 m/s
- Handbook shear moduli for the comparison table
- Assumed
- That light is a wave in a medium at all. The whole memo rests on this. Standard physics treats the electromagnetic field as a field rather than a disturbance in a substance, and nothing here compels the substance reading — it is the premise of the series.
- Void density ρ = 0.9 kg/m3, carried from memo 1.1, which sets the absolute value of G. The conclusion that G > 0 does not depend on it; only the number does.
- That matter is clumped Aether (memo 2.1). Section 5's answer to the drag objection fails without it, and the classical objection returns in full force.
- Open
- The rest frame. A solid has one, and it has not been found. This is the most serious unanswered objection to the framework, and it is not resolved here or anywhere else in the series yet — see memo 5.7
- The longitudinal wave that comes with rigidity is dealt with in memo 1.5 but its non-detection is argued, not demonstrated
- Whether a medium can be simultaneously this rigid and this lossless is a requirement stated in memo 4.2, not a derived result
- Prior art
- A. Fresnel, 1820s — established that light is transverse, and that this forces the aether to be a solid. The difficulty in this memo is his, not new
- Maxwell, Kelvin, Lorentz — all worked with an elastic aether and none resolved the drag objection. The answer offered in section 5 was unavailable to them because it requires matter itself to be made of the medium