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Does light have an infinite lifetime?

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Re: Does light have an infinite lifetime?

#71

Post by favflam »

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'…

Think of time as defined by how many times a photon bounces between two mirrors. If the two mirrors move at the speed of light with the photon, the photon will never reach the mirror to bounce. Therefore, the photon experiences no time.

There is no universal time T in space time. Time is relative to the observer.

I suggest reading https://en.wikipedia.org/wiki/Minkowski_space for the mathematics.

Re: Does light have an infinite lifetime?

#72

Post by dylan604 »

westmeal wrote: post #53
doodlebugging wrote: post #52

Earlier quoted context omitted.

I covered all those bases. I'm not 100% sure what happened but when I initially tried to start the vehicle I had it connected to a solar battery maintainer in full sunlight. It should've had bazillions of photons sacrificing part of themselves to be stored electrons but instead I got nothing. After disconnecting that from the battery and testing all the fuses I made another attempt to start it up and it worked fine.…

I find pouring electrons into a funnel usually helps by avoiding an electron spill all over your battery. Glad it works tho!

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

Re: Does light have an infinite lifetime?

#73

Post by cmsj »

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'…

I am not a Physicist, so please don't rely on this, but my understanding is that this comes down to the frames of reference in special relativity.

If you're in a car on the highway, an observer standing still outside the car sees you moving at 50mph, but an observer inside the car with you, sees you not moving at all, but the world rushing past at 50mph. These are two different reference frames, and the second one is called a rest frame - any object can be considered to have a rest frame of reference where it isn't moving at all. Any object that is, which has mass.

Massless objects are always observed to be moving at the speed of light by any observer in any frame of reference. This is one of the most mind-bending parts of relativity, but it ultimately connects to the part of special relativity where speed affects time - the faster you go, the slower your clock runs compared to things moving slower than you, and the closer you get to the speed of light, the closer your clock gets to zero. Massless particles only travel at the speed of light, and thus have no clock, therefore they experience no time.

I hope I got that right, but even if I did, I still don't feel like I actually understand it at all!

Re: Does light have an infinite lifetime?

#74

Post by cmsj »

AlexAndScripts wrote: post #44
prettydeep wrote: post #34

Earlier quoted context omitted.

Roger Penrose has a theory about a cyclical conformal universe, which requires that the universe eventually only contains photons. As photons travel at the speed of light, they do not experience the passage of time, so they also do not experience distance (space). So in the deep remote future, when only photons are left, the difference between the very large and miniscule disappears, and you get all photons in the un…

https://en.m.wikipedia.org/wiki/Conformal_cyclic_cosmology It seems the paper made mistakes, using a non-standard model of the CMB that failed upon replication. It's an interesting theory thoughb.

As a non-Physicist, I absolutely love the CCC hypothesis and I really hope it turns out to be true. It seems like such a beautiful alternative to the idea of the heat death of the universe just lasting forever and nothing ever happening again.

Re: Does light have an infinite lifetime?

#75

Post by pavel_lishin »

barfbagginus wrote: post #10
gwern wrote: post #2

Interesting. I had no idea that the universe would eventually be basically just photons. I wonder if that is why Stephen Baxter had his 'photino birds' as the final form of life in his Xeeleverse?

The photino birds want the universe to be populated with white dwarfs, because they can feed off their gravity wells without the risk of deadly supernovas and black holes, which can kill them. After the xelee and humans leave, the universe becomes a cold place dominated by photino birds living in the cold pinpricks of white dwarfs. Eventually matter evaporates into photons, and the photino birds die. However, it turn…

> However, Photino Birds carry with them one unassailable advantage the Xeelee could not overcome; they are not bound by time. They can freely exist in and travel to any point in time. The creatures do not age nor die naturally, not even by the end of the universe; they just travel back to the beginning of time, including to points so soon after the Big Bang that baryonic matter (including the Xeelee) could not yet exist.

Where is this described in the books? I don't remember the Photino Birds having this ability.

Re: Does light have an infinite lifetime?

#76

Post by doodlebugging »

DennisP wrote: post #57
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…

If you haven't yet, you should definitely read the famous little scifi story Light of Other Days . Full text: https://www.physics.utoronto.ca/~jharlow/slowglass.htm

Wow. Now that's nice. Someone thought outside our box for that story.

Part of the reason that I initially posted on this thread was to ponder the question about a world where mirrors have a memory function. A mirror with a memory would have perfect fidelity though the image would be a mirror image of reality, like looking into a replay from a mirror image universe. I wrote a poem on that subject a couple years ago and the whole question about photons and their potential infinite existence triggered the memory.

Re: Does light have an infinite lifetime?

#77

Post by doodlebugging »

westmeal wrote: post #53
doodlebugging wrote: post #52

Earlier quoted context omitted.

I covered all those bases. I'm not 100% sure what happened but when I initially tried to start the vehicle I had it connected to a solar battery maintainer in full sunlight. It should've had bazillions of photons sacrificing part of themselves to be stored electrons but instead I got nothing. After disconnecting that from the battery and testing all the fuses I made another attempt to start it up and it worked fine.…

I find pouring electrons into a funnel usually helps by avoiding an electron spill all over your battery. Glad it works tho!

So sorry for the delayed reply. I had to hit several O'Reilly stores to find someone who had any idea what I was looking for. I finally found one with a college-looking kid behind the counter instead of all those old farts like me and after I explained what I wanted he knew just which aisle it was on.

Turns out that an electron funnel isn't a fancy new tool. Instead, I already have several of them in my shop but just didn't make the connection. It became clear though when he handed me the plastic funnel after rubbing it through his hair vigorously for a few seconds and I got shocked by the crackling electrons streaming from the funnel to my fingers.

If this power thing ever happens to my battery again I'm just gonna get the big funnel from the set, rub it through the remnants of my hair and pour some electrons at it till it charges enough to start the engine.

Thanks for this suggestion about a new way to use an old tool.

Re: Does light have an infinite lifetime?

#78

Post by doodlebugging »

dylan604 wrote: post #72
westmeal wrote: post #53

Earlier quoted context omitted.

I find pouring electrons into a funnel usually helps by avoiding an electron spill all over your battery. Glad it works tho!

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.

Re: Does light have an infinite lifetime?

#80

Post by x86x87 »

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.
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