'Cosmic Metamaterial' to Zoom In on Early Universe


He’s baaaaack! University of Maryland physicist Igor Smolyaninov made headlines a year ago by suggesting that so-called “metamaterials” might be able to simulate the effects warp drive would have on the path of light. He’s also mused on the possibility of creating metamaterial analogs of black holes and quantum foam.

Now Smolyaninov has got a new paper on the arXiv proposing that the quantum vacuum of space itself might behave a bit like a metamaterial, in that it can act as a sort of “superlens” under certain conditions.

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Even better, this “cosmic metamaterial” could have left detectable imprints in the large-scale structure of the universe.

Metamaterials are special because they have been engineered to exhibit unusual properties, particularly with regard to how light behaves when it passes through such materials.

For instance, scientists have created metamaterials with a negative index of refraction (known as “left-handed materials”). The effect is a bit like dropping a pebble in a calm body of water and having the ripples spread inward, rather than outward.

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That property could potentially reflect light in such a way to make ordinary objects invisible to the naked eye, or to “cloak” objects from radar.

Metamaterials can also provide a means of simulating how light would behave under extreme gravitational conditions — for instance, in a black hole, or in the phenomenon of gravitational lensing.

The latter was first observed in 1979, when astronomers noticed that a large galaxy could interrupt the line of sight to a distant galaxy and warp the resulting image. Per general relativity, matter bends spacetime and as light travels through this bent spacetime, the light’s path will be deflected.

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Like a glass lens being placed in front of a light bulb, the light will distort from our viewpoint — the heavier the mass, the greater the distortion. So it produces an image of a distant quasar, for example, or another galaxy that is magnified and split by the foreground galaxy.

Gravitational lensing has become an important tool for astrophysicists keen on measuring the mass of distant galaxies, or perhaps for mapping dark matter. Smolyaninov thinks it might be possible to play equally exotic tricks with light by exploiting unusual properties of the quantum vacuum.

At the subatomic scale — the quantum world — space is not the smooth, flat geometric entity that Einstein envisioned when he devised relativity. It is frothing with virtual pairs of particles and antiparticles that pop into existence for the briefest of moments before annihilating back into nothingness. But if you apply a strong electric field, for example, some of those virtual particle pairs can manifest as “real” — something comes out of nothing.

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Recently, physicists realized that if you apply a powerful magnetic field to the quantum vacuum, you can produce a certain type of charged mesons that act like a superconductor — conducting electrons with almost zero resistance — as it follows the lines of the magnetic field. Smolyaninov noted the similarity of this effect with that of a metamaterial on light.

Specifically, he theorizes that if such a strong magnetic field were to propagate through space in just the right way, it could create a “superlens” for focusing light — or perhaps even trap light completely, just like with a black hole.

The catch: it’s no small feat to generate that powerful of a magnetic field; it’s far beyond our current technological capabilities. But in the earliest moments of our universe, Smolyaninov proposes, fractions of a second after the Big Bang, there would have been magnetic fields of that magnitude.

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And that means that there should be evidence of all this focusing and trapping of light through a “superlens” in the universe we see today, imprinted onto its large-scale structure. Ah, if we only had instruments capable of detecting those imprints from those few fractions of a second of the birth of the cosmos.

The Cosmic Microwave Background Radiation — that faint afterglow leftover from the Big Bang — only lets us see as far as 380,000 years after the Big Bang. And by measuring the abundance of light elements, physicists have been able to roll back the clock to within a few seconds after the Big Bang. But that’s where our “eyes” fail us, at least to date.

There’s always a caveat, isn’t there? But it’s an interesting paper, nonetheless, and a nice addition to Smolyaninov’s growing body of work in this area.

Image credit: NASA

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