A primary constant of the Universe
Lucio Cavallari, August 2023
Midsummer sky by the ocean is all blue, the horizon line that once defined water from air has disappeared. Suspended, afloat, muffled by the water, belly up, playing dead I and the sea. This is one of my favourite views of the world, an early peek to the first light that comes in.
Serene, in utero.
A perfect realm beyond the limitations of our physical world. It does look tangible from down here, when in a good mood you almost can have the feeling of touching it, yet from outer space… that’s another story.
A one way dream. An always bluer invisible cloak.
150 million Km and 8 minutes later, scattered by some tiny air molecules, bouncing all around, absorbed, reflected, almighty light is here but there. Golden tongues quietly scream, shimmering infinite, eternal: like a belly dancer on steroids, serpentine moves from outer space mesmerise any sight dizzyingly. Light is fast, finite fast. These quanta of light are long way travellers.
How far is 150 million Km? If we were to visualise the distance with lined-up apples of a diameter of 8cm, according to chatGTP, we’d need approximately 1.875 trillion apples. And then you may ask yourself: how long would it take for a human to eat all these apples? Well, if the calculations are correct, chatGPT says it would take around 6.77 billion days and adds: to put this in perspective, an average human lifespan is around 70 to 80 years (which is about 25,550 to 29,200 days). So, eating 1.875 trillion apples at the speed of 5 minute each it would take from 262,000 to 282,000 times the span of a human lifetime!
Keep in mind that this is a fun hypothetical calculation, and in reality, the apples would likely spoil long before they could all be consumed, chatGPT said and go find a human that would spend an eternity eating apples I say. Anyhow who cares about apples, I do apparently, as I kept asking chatGTP how many photons would fit in one of these apple: 1.91 quadrillion visible light photons – based on some rough estimations. Every second a staggering number of around 7.91 x 1035 visible light photons reach Earth. Over the course of 24 hours, that number would be even more immense.
Big data. Lot’s of particles.
The geometry and trajectories seems pretty solid, yet massless. Fried Air “Aria Fritta” as we say in Italian. Well turns out that the universe is all about energy, and some of it is well old. Sometimes I wish we could shoot particles from our eyes as fingers touching surrounding objects as Greek philosophers once thought, and I’m ok knowing we are almost blind as we only perceive a tiny segment of the optical radiation, and that we can forget real-time as we can sense only the past – due to the finite speed of light and the considerable delay the nervous messages reach the brain1,
BUT overall I think we can consider ourselves pretty lucky photons are not as hard as apples.
- R L. Gregory, Eye and Brain : The Psychology of Seeing. Princeton, N.J., Princeton University Press, 2015, 10. ↩︎