From the tinest possible expanse to the farthest reach, from the Planck length to the edge of the universe; somewhere in the middle, there is the world inhabited by humans.
1. Planck: The Planck length is the length at which classical ideas about space-time and gravity cease to be valid. Quantum effects dominate. The quantum length is the smallest measurement of length with any meaning. This distance is in the order of 10^-35m.
2. Neutron: Massively greater in scale compared to the Planck length, (by 20 orders of magnitude), the femtometre or fermi describes the atomic scale, the radius of a proton or neutron. This distance is in the order of 10^-15m.
3. Violet: We start to approach the visible but we are still in the nano-realm of the microscopic. The wavelength of ultraviolet light is shorter than that of visible light, but U-V can cause substances to glow, and it has several biological effects. The track features the voice of my daughter, Violet. This distance is in the order of 10^-7m.
4. Human: Another leap of many orders of magnitude brings us into the scale of the human, and our familiar world. Lying in the centre of our number system, this distance is in the order of 10^0m, that is, one metre - or two; a doubling is insignificant in the context of the leaps in magnitude between the distances described.
5. Chang'e: The Chinese goddess of the Moon, and in modern times, the namesake of the Chinese lunar exploration program. A constant companion to the humans of Earth since the earliest days, our Moon is at a distance from us in the order of 10^8m, and is therefore as great a leap up in magnitude away from the human scale as the leap down to the ultraviolet, or between the ultraviolet and the fermi or atomic scale.
6. Proxima: The nearest star to Earth (other than the Sun) is Proxima Centauri, a red dwarf, tiny compared to our Sun and invisible to the human eye, but still a roiling mass of super-hot plasma, and with an estimated lifespan far greater than that of our own Sun. When we, our Earth, and our Sun are long gone, Proxima Centauri will continue to spill weak light into the universe for billions of years. The distance to Proxima Centauri is in the order of 10^16m: as the distance to the Moon is to human scale, and the human scale is to the ultraviolet, so is the distance to Proxima centauri. The leap up in distance magnitude to Proxima Centauri from human scale is similar in order to the leap down from human to atomic scale.
7. GN-z11: At the very upper limit of what it is possible to observe, where to peer into the distance is to stare into the distant past, there is a galaxy at the edge of the universe, GN-z11. We see it from Earth as it existed 13.4 billion years ago, just 400 million years after the Big Bang; by comparison our Earth formed a mere 4.5 billion years ago, with the first land animals - our ancestors - appearing around 400 million years ago. The distance to GN-z11 is, however, far more than 13.4 billion light years; taking into account redshift, the distance to GN-z11 is in the order of 10^26m, and is therefore effectively at the edge of the observable universe. GN-z11, a vast mass of stars, millions upon millions of worlds, may today no longer exist: we observe it only in its distant past.
The leap in magnitude from the human scale to the distance of GN-z11 is still far short of the leap in magnitude from the Planck length to human scale, by 9 orders of magnitude - a billion times. Yet still we humans are able to conceive of the unconceivable, to imagine the unimaginable, these Distances.
released May 4, 2016
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