Discussion How are light and time related?

[IronWing]

As always, it's up to the person making the assertion to provide the evidence. I say souls are farts. Once you've completely depleted your reserve of soul, you die.

You’ve killed Sam and Dave for me.

 

[IronWing]

This is definitely one of those "do your own research" situations! I'll report back!
(I probably won't remember)
View attachment 101201

Vegetarian owl pellet?

 

[WelshBloke]

Vegetarian owl pellet?

Ha! That reminds me of a conversation I was having last week.
Medical cannabis is pretty strictly controlled in the UK, you have to have a prescription from a qualified doc (like a consultant psychologist or equivilant) and they communicate with your GP about it.
I was chatting with my GP about it (shes prety chill and was interested) and I was telling her how professional the set up was and generally trying to show that it was a legit medical thing and she asked me what I'd been prescribed and I had to say I have a prescription for "green crack and wedding pop triangle"!

 

[nOOky]

The universe is expanding faster than the speed of light, so if you were traveling towards the edge to see what's out there, you'd never catch up. There are particles that travel faster than the speed of light. Chuck Norris has counted to infinity, twice. He also can catch a boomerang before he throws it, can pick himself 3 feet off the ground by his own collar, and can attend a women's liberation rally and come out with a freshly ironed shirt and a homemade ham sandwich and lipstick on his cheeks.

Anyone got the time?

 

[SteveGrabowski]

Isn't it peculiar that it is thought that time does not flow inside a blackhole and a blackhole is the only known entity that "eats" light? Everywhere else, light either continues on its trajectory forever or until it hits something, then light particles are scattered around but they don't stop. If they are absorbed by some material, their energy is transferred to the material's subatomic particles and that energy as far as I know, does not dissipate into nothingness. It keeps being transferred and flowing, just like time.

Anything with mass causes light to change direction via gravity. Einstein's theory of general relativity was established when we were able to measure that the sun's gravity bent the path of light from distant stars that passed near the sun on the way to Earth. A black hole bends spacetime in on itself so the only path light (or anything else) can move on is directly towards the singularity at the center of the black hole once it has crossed the event horizon. That energy isn't lost. The black hole should eventually emit it back out as Hawking radiation.

 

[SteveGrabowski]

This is almost right, except it's not a tennis ball. It's a light clock.

Light always moves at the same speed for all observers. So if the clock itself is moving...

...time must slow down. 🤔

Yeah if you're looking at this from the outside of the train passing by you see clocks in the train ticking more slowly than the clock on your phone or the watch on your wrist. Seems like lunacy but Einstein's reasoning was if mechanical phenomena obey (Galileo's law of) relativity, eg moving at a constant velocity imparts no force on you so your mechanical laws of physics are the same, electromagnetism should too, and thus light being an electromagnetic wave must also. If light didn't behave this way you could use a light clock to discern whether the train you were inside of was stopped relative to the ground or moving at constant nonzero velocity.

 

[SteveGrabowski]

Wut? Educate me on that last part. I’m not good at reading about that stuff but I am good at understanding explanations.

Hawking radiation is pretty weird. Not a physicist but I think it goes something like this: Think of the event horizon of a black hole - inside the event horizon spacetime is so heavily curved so that the only path anything can take is towards the singularity at the center of the black hole. Outside the event horizon the curvature is lowered enough that its still possible for something moving at or just a tiny bit below the speed of light to make it out. Now quantum field theory tells us we constantly have pair creation events where a pair of particles is created from nothing and very quickly annihilate each other so on average there is nothing there. When this pair creation happens right at the event horizon with one of the particles inside the border and the other outside it the one inside is forced to go towards the singularity while the other outside might escape. That particle outside the event horizon is Hawking radiation when it escapes the black hole and thus can't annihilate with its partner which is stuck moving towards the singularity at the center of the black hole. If I remember right it's supposed to take on the order of a trillion years for a stellar sized black hole, eg a black hole created by the collapse of a dead star, to dissipate its energy/matter from emission of Hawking radiation.

 

[SteveGrabowski]

Relativity is fun. I love this book called Spacetime Physics that is the best description of Special Relativity I have ever seen. Supposedly the second edition isn't nearly as good as this first edition, as seems to be the case most of the time at least when it comes to math books that tend to get bloated with every new edition. Probably similar with physics books.

Amazon.com

 

[[DHT]Osiris]

Wut? Educate me on that last part. I’m not good at reading about that stuff but I am good at understanding explanations.

There's been several theories brought up over the years, but one developed in 2001 is that classical black holes are actually gravastars, otherwise to be considered 'dark matter' stars.

Black hole singularities defy physics. New research could finally do away with them.

Black hole singularities defy the laws of physics. New research presents a bold solution to this puzzle: Black holes may actually be a theoretical type of star called a 'gravastar,' filled with universe-expanding dark energy.

www.livescience.com

TLDR: might match our observations better than a black hole does, and doesn't require physics-defying singularities.

I suspect the whole mess is drek, nothing but false objects projected by our simulation.

 

[igor_kavinski]

Theres not a lot to research. Where do you start? Theres no physical presence at all and theres no physical process that needs a soul to explain it.

There was this: https://www.discovermagazine.com/mind/the-man-who-tried-to-weigh-the-soul

That's the problem with modern science. Certain stuff will be categorized under the term "pseudoscience" by extremely vocal opponents and immediately declared a waste of time to research it any further, even though no convincing evidence is provided to refute the proposed notion.

 

[SteveGrabowski]

I love this video narrated by Ronan Plesser from Duke in this free online astronomy course he gave maybe ten years ago showing what approaching and later falling into a black hole would look like and how much a black hole's gravity warps light.

The course was amazing btw and didn't require any math higher than highschool algebra. I'll link the entire playlist for the course too:

Introduction to Astronomy - Ronen Plesser

Share your videos with friends, family, and the world

www.youtube.com

 

[igor_kavinski]

Here's another "can of worms" thought experiment:

Microgravity causes the process of aging to accelerate. This means that the proper physiological functioning of living organisms depends on the strength of gravity.

Does gravity make you age more slowly?

If you're at sea level, or you age more slowly or faster than someone at the top of Mount Everest?

www.livescience.com

What happens when the gravity is higher than that of Earth? What would happen to someone living near a blackhole?

Immortality or spaghetti? What happens if you park inside a black hole?

Black holes are awesome. They make great inspiration for 1990s grunge rock anthems, they're really good at having gravity, and they make spaghetti.

thenextweb.com

So if we assume that gravity does increase lifespan, we can now tackle another matter: https://www.jw.org/en/library/magazines/wp20101201/Did-People-in-Bible-Times-Really-Live-So-Long/ <<< link just an example. I'm not of JW faith.

If we take that at face value, it would seem to suggest that Earth had more mass in earlier times due to which it had much stronger gravity and this gave rise to lifespans measured in hundreds of years. So how would a planet lose its mass over time? Could be hot gases escaping the gravity well of the planet. Can anyone think of any other process(es) that would reduce the mass of a planet?

 

[BoomerD]

The light shines on the clock, which allows you to see the time. If it was not for light we wouldn't know what time it is.

Does anybody REALLY know what time it is? Does anybody really care?

I'm not too sure time and light are related other than the time it takes for photons to travel...but I damned well know space and time are connected...and there's a rift just outside of Cardiff, allowing the "flotsam and jetsam of the universe since the dawn of time" to pass through.

 

[ssokolow]

PBS Space Time has excellent videos on all of this if you want a gradual ramp into understanding the physics of this sort of thing, presented by an actual professor with an engaging style and very intuitive animated diagrams.

The gist of it is that, from its own perspective, light is emitted and absorbed at the same instant and "the speed of light" is a misnomer because it's actually the speed of causality. (i.e. the maximum speed at which cause and effect can propagate through space)

For example:

The True Nature of Matter and Mass talks about how matter itself doesn't have mass... mass is actually how we perceive the side-effects of the presence of energy binding the pieces together... and that's why wound springs and faster moving things weigh more than unwound springs and still things if you've got a sensitive enough instrument to measure it. (And also why you can't reach or surpass the speed of light. When you get to relativistic speeds, the energy of your momentum gets significant and it starts taking exponentially more fuel to accelerate more.)


When Time Breaks Down uses the light clock to explain how the flow of time emerges from motion and how time dilation emerges from that cosmic speed limit.

...and both cross-reference other relevant videos.

 

[ssokolow]

Here's another "can of worms" thought experiment:

Microgravity causes the process of aging to accelerate. This means that the proper physiological functioning of living organisms depends on the strength of gravity.

Does gravity make you age more slowly?

If you're at sea level, or you age more slowly or faster than someone at the top of Mount Everest?

www.livescience.com

The problem is that you're conflating two different effects. Microgravity is bad for human health for a variety of reasons that have nothing to do with time dilation and everything to do with "operating the system outside design tolerances"... similar to how overvolting a CPU shortens its lifespan or running a system with too much or too little cooling can cause cracking due to stresses between materials that expand/contract at different rates for the same amount of temperature change. (eg. the XBox 360 Red Ring of Death was from chips cracking loose from the solder points on the circuitboard due to excess heat IIRC.)

As for time dilation, the problem there is one of scale. The time dilation we experience in any normal environment is measurable but miniscule.

What happens when the gravity is higher than that of Earth? What would happen to someone living near a blackhole?

Immortality or spaghetti? What happens if you park inside a black hole?

Black holes are awesome. They make great inspiration for 1990s grunge rock anthems, they're really good at having gravity, and they make spaghetti.

thenextweb.com

If you go somewhere like near a black hole, then tidal forces start to become a concern even before spaghettification. (i.e Where the gravity on one end of your body/ship is different enough from the gravity on another that the difference can tear you apart.)

A related phenomenon is the Roche limit which refers to how close something like a moon can get to a planet before the tidal forces overcome the self-gravity holding the moon together and pull it apart.

Larry Niven wrote a short story named Neutron Star where tidal forces were the central driving force of the plot that I highly recommend if you're into science fiction. Among other places, it's part of Cosmic Critiques: How & Why Ten Science Fiction Stories Work.

So if we assume that gravity does increase lifespan, we can now tackle another matter: https://www.jw.org/en/library/magazines/wp20101201/Did-People-in-Bible-Times-Really-Live-So-Long/ <<< link just an example. I'm not of JW faith.

If we take that at face value, it would seem to suggest that Earth had more mass in earlier times due to which it had much stronger gravity and this gave rise to lifespans measured in hundreds of years. So how would a planet lose its mass over time? Could be hot gases escaping the gravity well of the planet. Can anyone think of any other process(es) that would reduce the mass of a planet?

First, to have the desired degree of time dilation, Earth would have to have so much more mass that the solar mechanics would break... also, there's no plausible mechanism for that mass to go away without something like a world-ending impact.

Second, if you're inside the gravitational field, you won't perceive time flowing any differently. You'll still live to 60 or 70 or 80 or whatever... you'll just see the sky changing more slowly.

 

[ssokolow]

There was this: https://www.discovermagazine.com/mind/the-man-who-tried-to-weigh-the-soul

That's the problem with modern science. Certain stuff will be categorized under the term "pseudoscience" by extremely vocal opponents and immediately declared a waste of time to research it any further, even though no convincing evidence is provided to refute the proposed notion.

...though the definition "proper" (i.e. unbiased) scientists use for science vs. pseudoscience is something along these lines:

Because even scientists fall prey to the human tendency to fool ourselves occasionally (see N-Rays, Polywater, and Cold Fusion), we have to be very careful to design our methodologies to push back against that.

The core of the distinction between science and pseudoscience is: Scientists aim to gather data first, then hypothesize, then test that hypothesis, while always looking for opportunities to falsify what they believe to be true. The "truth" is whatever is currently resisting falsification most strongly. Pseudoscientists have something they want to be true, and then seek out evidence to support it.

The problem is that history has shown us it's far too easy to convince ourselves of the truth of something that isn't true to our own satisfaction. (See, for example, epicycles.)

EDIT: Throw in Occam's Razor (that history has shown that the explanation that introduces the least new unproven complexity is almost always the correct one) and the Sagan Standard (stated less punchily but in a more difficult-to-take-incorrectly way as "claims out of the ordinary require evidence that's out of the ordinary to the same degree") and something like the existence of the soul becomes a case of "We don't currently observe anything that would justify such a whole new facet of reality."

(Things like "paranormal" run afoul of "If it has an effect on anything science can measure, then it can be theorized about and tested. If it can be theorized about and tested, then it's science. Conversely, if it has no measurable effect, then it's indistinguishable from fiction for all intents and purposes." Basically, the scope of science grows to encompass anything that can be proven to exist.)

 

[WelshBloke]

There was this: https://www.discovermagazine.com/mind/the-man-who-tried-to-weigh-the-soul

That's the problem with modern science. Certain stuff will be categorized under the term "pseudoscience" by extremely vocal opponents and immediately declared a waste of time to research it any further, even though no convincing evidence is provided to refute the proposed notion.

But that's entirely the wrong way round and totally "pseudoscience".
An actual science thing would be someone notices that the body loses weight at the moment of death and then conducts experiments to work out why.
In your example someone has decided (without any supporting evidence or even need) that the soul exists and they are going to find things that support that.