Does light have an infinite lifetime? • Hacker News Board

Re: Does light have an infinite lifetime?

#81

Post by akomtu » Sat, Apr 20, 2024, 2:22 AM UTC

x86x87 wrote: post #80

akomtu wrote: post #29

Isn't it a meaningless question? Photons aren't things, but loosely localized areas of motion energy that's temporarily assumed the shape of a photon. Upon collision with other similar waves, it may change shape and become another partickey like an electron. But the light itself is a motion itself, which is a pure abstraction. At the end of the universe, photons probably will keep spreading over larger and larger are…

Yeah, this is like asking if energy has an infinite lifetime.

My suspicion that everything is made of pure abstract motion can be backed with a thought experiment. A spaceship with a light sail uses kinetic energy of photons that hit the sail. We know that anything can be dissolved into photons, we even know the exact amount of those photons from the e=mc2 formula, and when all those photons hit the light sail, they vanish from existence and become the kinetic energy of the spaceship. And what is kinetic energy? It's not even real. And as we know from the relativity theory, even as an abstraction, kinetic energy can't be measured with an absolute number, it has to be measured with respect to some imaginary reference frame.

Re: Does light have an infinite lifetime?

#82

Post by akomtu » Sat, Apr 20, 2024, 2:54 AM UTC

dataflow wrote: post #70

henry2023 wrote: post #67

From the perspective of a photon, there is no such thing as time. It's emitted, and might exist for hundreds of trillions of years, but for the photon, there's zero time elapsed between when it's emitted and when it's absorbed again. It doesn't experience distance either.

Something about this doesn't make sense. This means that, from its own perspective, every photon is emitted at time T at location x, then absorbed at time T at location y, meaning there is no time "in between" those... yet somehow, at a distinct point in between those events, an object can get in the way and block the photon from reaching point y. Meaning you have two points in time that have the same value but aren'…

If time doesn't exist objectively, then there's no puzzle. What if photons are thin threads connecting distant things. The entire web of these light threads remains still, like an art sculpture. We may explore thin slices of this sculpture, one after another, and this slideshow will create an illusion that a few points, where the light threads cross the slices, move. We may try to find such a slice of this sculpture that the light threads would be seen in their entirety. Such a slice exists, but the light thread on it appears so densely packed that it fills the entire slice. It's truly everywhere on the slice. It's quite possible that in this sculpture all the light threads are really one thread.

Re: Does light have an infinite lifetime?

#83

Post by _factor » Sat, Apr 20, 2024, 3:16 AM UTC

doodlebugging wrote: post #37

Where do the photons that hit my retina go when I finish with them? If they have infinite lifetimes then does each one carry a memory of it's creation event? When I burn a log in my fireplace and a cinder flares and pops creating a spark, does the photon exist after the spark energy flares out and the cinder is no longer illuminated enough to be detected by my eyes? If photons are infinite then harvesting light would…

What makes you so sure the photon didn’t originate from your eye and finish where you saw them?

Re: Does light have an infinite lifetime?

#84

Post by ipqk » Sat, Apr 20, 2024, 3:33 AM UTC

cwoolfe wrote: post #42

pc86 wrote: post #22

Earlier quoted context omitted.

Do you have something constructive to add related to the content of the article or are we just quoting random bible verses on HN for no reason?

"The light shines in the darkness, and the darkness can never extinguish it. God sent a man, John the Baptist, to tell about the light so that everyone might believe because of his testimony. John himself was not the light; he was simply a witness to tell about the light. The one who is the true light, who gives light to everyone, was coming into the world. He came into the very world he created, but the world didn’t…

cool story, bro.

Re: Does light have an infinite lifetime?

#85

Post by bobbylarrybobby » Sat, Apr 20, 2024, 4:09 AM UTC

akomtu wrote: post #81

x86x87 wrote: post #80

Earlier quoted context omitted.

Yeah, this is like asking if energy has an infinite lifetime.

My suspicion that everything is made of pure abstract motion can be backed with a thought experiment. A spaceship with a light sail uses kinetic energy of photons that hit the sail. We know that anything can be dissolved into photons, we even know the exact amount of those photons from the e=mc2 formula, and when all those photons hit the light sail, they vanish from existence and become the kinetic energy of the spa…

The light also doesn't have an absolute energy though; like the ship's kinetic energy, the light’s frequency (hence energy) also depends on your relative speed.

None of this stuff is “real”, but boy does the bookkeeping seem to work out...

Re: Does light have an infinite lifetime?

#86

Post by bobbylarrybobby » Sat, Apr 20, 2024, 4:12 AM UTC

xyzelement wrote: post #51

ClarityJones wrote: post #31

Earlier quoted context omitted.

It wasn't exactly random. The topic of the article is that light is eternal, and the commenter shared a quote from over a thousand years ago stating the same thing. So, the idea of light having an infinite lifetime is apparently not new... even if the mechanics of light are better understood these days.

This is in line for me with the moment of "creation." For most of the history of science as a thing, the scientific view held that the universe was infinitely old cosmos without a beginning or end. The greek model. It was only in 1900s that big bang was theorized (by a catholic priest) that science now views that there was a moment before which the universe didn't exist and after which it did. The fact that someone r…

Broken clocks...

Re: Does light have an infinite lifetime?

#87

Post by Leftium » Sat, Apr 20, 2024, 4:28 AM UTC

dataflow wrote: post #70

henry2023 wrote: post #67

From the perspective of a photon, there is no such thing as time. It's emitted, and might exist for hundreds of trillions of years, but for the photon, there's zero time elapsed between when it's emitted and when it's absorbed again. It doesn't experience distance either.

Something about this doesn't make sense. This means that, from its own perspective, every photon is emitted at time T at location x, then absorbed at time T at location y, meaning there is no time "in between" those... yet somehow, at a distinct point in between those events, an object can get in the way and block the photon from reaching point y. Meaning you have two points in time that have the same value but aren'…

If something blocks the photon, that was "agreed" upon before the photon was created.

A photon travels between an electron that emits it and an electron that absorbs it. These two electrons must agree on the photon transfer beforehand. This has some strange implications:

- When you see a star at night, it's because photons from the distant star hit your eyes.

- These photons started traveling billions of years ago, when neither you nor your eyes existed yet.

- Yet the electrons in your eyes and the electrons in the star (which may no longer even exist) must have agreed to transfer these photons.

- From the photon's perspective, it traveled instantaneously from the star to your eye; it traveled through billions of years of time!

Source: https://www.youtube.com/watch?v=bAedYtUredI&t=2630s

Re: Does light have an infinite lifetime?

#88

Post by Leftium » Sat, Apr 20, 2024, 4:35 AM UTC

urbandw311er wrote: post #66

Anybody care to attempt a TL;DR of this?

Kagi Summary:

The passage discusses whether photons, the quantum particles of light, have a finite or infinite lifetime. It explains that while photons can be created and destroyed through various interactions, they cannot truly be "killed off" entirely. Even as the universe expands and photons redshift to lower and lower energies, new photons will continue to be produced, ensuring that photons will always exist in some form. The passage also dismisses the "tired light" hypothesis as a way for photons to lose energy, as it is not supported by observational evidence. Overall, the passage concludes that based on our current understanding of physics, photons appear to have an infinite lifetime and will continue to exist in the universe indefinitely.

Re: Does light have an infinite lifetime?

#89

Post by rkagerer » Sat, Apr 20, 2024, 6:02 AM UTC

doodlebugging wrote: post #78

dylan604 wrote: post #72

Earlier quoted context omitted.

I wonder if that's how they get electrons into the particle accelerators too?

They gotta get'em somewhere. Seems easy enough to do it like that.

Yeah but they just don't make 'em like they used to.

MBA's took over and cut corners everywhere - sourcing production from subpar isotopes, skimping down how much charge you get in each one, shrinkflation schemes packing less in every bag of amps, particle dilution with off-brand fake leptons... QA was downsized 'till all you got was beta junk that decays in no time. Now they just rent seek that single universal virtual electron, unlocked by keys you're forced to tie to the cloud, and it can be glitchy and pop in and out of existence from time to time especially driving through tunnels. Sorry to hear about your car, try upgrading to the new positron model on the roadmap for next year, they launched the presale NFT last week.

Re: Does light have an infinite lifetime?

#90

Post by fnordpiglet » Sat, Apr 20, 2024, 6:23 AM UTC

doodlebugging wrote: post #37

Where do the photons that hit my retina go when I finish with them? If they have infinite lifetimes then does each one carry a memory of it's creation event? When I burn a log in my fireplace and a cinder flares and pops creating a spark, does the photon exist after the spark energy flares out and the cinder is no longer illuminated enough to be detected by my eyes? If photons are infinite then harvesting light would…

Photons don’t experience time, from their relativistic frame they are created and destroyed instantly. This is because they are massless and therefore always travel at the speed of light. Due to relativity they experience a different simultaneity - in our reference frame we can observe their emission and absorption as energy and existence and measure them etc but, even given they can’t experience anything anyways, time doesn’t pass for them. This is one of the weirdnesses of relativity.