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Comments
Amoyamoyamoya t1_j9njbva wrote
Fascinating both for the story itself and the world building. Definitely worth a read.
CJ4700 t1_j9nl8v9 wrote
Thanks for recommending this. I just listened to the preview and bought it.
BeepBlipBlapBloop t1_j9nlez8 wrote
You're welcome. I hope you enjoy it. I did.
SW_Zwom t1_j9nkuqn wrote
I wouldn't call it a great book... The book itself is mediocre, imho, but the idea behind it is very interesting, so yeah, it's still worth the read.
Siliskk t1_j9ngh80 wrote
I will look into this! Appreciate it, i hope its on audible
Siliskk t1_j9ngwhi wrote
Perfect, who is the author? Their seems to be multiple books of the same title. Thank you
VitaminPb t1_j9nhv4h wrote
IIRC it was Dr. Robert Forward.
professorjaytee t1_j9nn8hg wrote
He means this Dragon's Egg:
https://en.wikipedia.org/wiki/Dragon%27s_Egg
The science in this book is as factual as hard science fiction can get. Zero handwaving or fantasy physics.
Bob Forward was not just an author, he was a career physicist.
>Robert Lull Forward (August 15, 1932 – September 21, 2002) was an American physicist and science fiction writer. His literary work was noted for its scientific credibility and use of ideas developed from his career as an aerospace engineer. He also made important contributions to gravitational wave detection research.
There aren't many people who can do both those things well.
[deleted] OP t1_j9ngjaj wrote
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[deleted] OP t1_j9nj3sj wrote
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wenkafonte t1_j9npfky wrote
I was just going to recommend this book. Finished it a few months ago on audible and it creeps into my thoughts regularly.
No-Percentage4385 t1_j9ng5pq wrote
You're onto something. Let me get back to you after I unfold my brain from the time/space dimension.
Siliskk t1_j9nge4r wrote
Appreciate the comment! This has been stuck in my mind rhe past few days and i finally decided to ask here
i_can_has_rock t1_j9nlnlp wrote
tl,dr: i agree with you and my similar theory is the same as yours, just a few orders of magnitude out from the center but still applies to what your saying
ive had a very similar thought and took it to the extent that time outside of the reach of the black hole in the center of a galaxy may be almost immeasurably different than anything caught in its field past the very edge of the field. the true time constant. essentially viewing a galaxy from the point of view where you arent affected by dilation at all; to me, would seem that every galaxy would pop in to and out of existence almost immediately. all observable light from other galaxies would essentially be filtered through our own galaxy's black hole dilation gradient; so, its entirely possible that both perspectives are happening simultaneously; which would infer that, if we ever left our galaxy to get to another galaxy, it would have already evaporated because we left the dilation field.
your line of reasoning seems sound to me. the only thing that might vary between your hypothesis and reality would be the varying degrees of dilation vs the distance to the black hole
the whole thread ended really badly for me, so good luck
MrTurdFace69 t1_j9nvcnk wrote
There is no true time constant. It's all relative, as Spacetime is curved by mass/energy. So there doesn't exist a point that isn't affected by mass/gravity, that we know of.
There is no end to the gravitational field a black hole produces. In fact there is no end to the gravitational field that your body produces.
They both extend the entire universe. However, far enough away, their effects become negligible.
If there are two 1kg spheres of metal in space, and they are 1 meter apart. Then, to the human eye, it seems like they experience no gravitational effect.
Yet they will experience the same gravitational effect that 2 earth mass objects would experience when they are 6x10^25 meters apart.
I think what you're trying to understand is sort of what Einstein was trying to understand when he was figuring out how to imagine what happens if you could travel along side by side with a beam of light. Which would basically mean you experience no time.
However, he concluded it's not possible to accelerate to that speed and that the speed of light was constant for all observers, and hence came up with the special relativity theory. Which eventually led to general relativity. Which, ironically in this discussion, predicted black holes haha.
i_can_has_rock t1_j9q9uny wrote
let me simplify
there -is- a true time constant that isnt affected by dilation or relativity
it exists as an abstract by itself and isnt dependent on either of those
is what im saying
MrTurdFace69 t1_j9rwanz wrote
But I'm saying that doesn't exist in reality whatsoever.
If you have mass (or even light itself does this) in this universe, then you will effect the time dilation of other mass objects and they will effect you. These effects permeate all of the universe.
Sure, you can imagine such a place. But so what? It wouldn't apart of this universe, because by definition it can't be.
If you're just using this as an imagination technique to describe what you'd see the universe do if you experience no time, then ok. But I don't think referring to relativity is necessary in that instance. I mean you could just instead say "what would the universe look like if I experienced no time?"
[deleted] OP t1_j9t86dj wrote
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CommentToBeDeleted t1_j9nh11x wrote
Absolutely!
In fact we already know this to be true. Our satellites experience time at a different rate than we do on earth and for that reason we must account for it when making calculations.
Your head and get agree differently too just due to their proximity to the earth.
Generally these things are so miniscule we will never be able to perceive them.
Siliskk t1_j9nha56 wrote
What about the fictional planet from interstellar, where 1 hour is 7 earth years on the planet? If thats possible, i see no reason to not believe that there are planets experiencing many years in the matter of a short time for us
Ape_Togetha_Strong t1_j9nrass wrote
> i see no reason to not believe that there are planets experiencing many years in the matter of a short time for us
Well, one good reason is "time dilation doesn't work like that". You can't have negative velocity or negative mass, so nowhere in the universe is significantly faster than on Earth.
Know0neSpecial t1_j9nlem5 wrote
This could be the case.. however any civilization that does this puts themselves at risk of being inferior to the civilization that 'had more time' to develop superior technology while they were in proximity to the gravity well
[deleted] OP t1_j9ngas3 wrote
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Delicious_Wrap4944 t1_j9ng8wk wrote
It’s relative to gravity/speed time is slower on the space station than on the earth surface. It’s only really noticeable on the extreme scales of gravity or speed such as 99% the speed of light or a blackhole.
Siliskk t1_j9ngcw0 wrote
Assuming galaxies spin around their black holes, wouldnt a planet closer to the center move alot faster and therefore experience time alot faster?
Nerull t1_j9nh2oj wrote
A planet near the black hole would experience time much slower, not faster. Being in a gravity well slows down time relative to a point far away from it.
Delicious_Wrap4944 t1_j9ngjm6 wrote
Yes but again it’s really only noticeable towards to unimaginable extremes with things like that we are talking only a few seconds maybe different for an entire year max. You probably can’t get to or will not survive anything that’s in the extremes
Siliskk t1_j9ngs4u wrote
Sorry for the continued questions but would this apply to galaxies further out towards the edge of the expanding universe considering the universe is expanding so fast that galaxies are moving away from us at (cant remember the exact speed) lets say lightspeed? Appreciate your time, just a boggling thought
Delicious_Wrap4944 t1_j9nhcwe wrote
To the observer us say a galaxy moving away at the speed of light time would stop for them as we view it because the light would no longer be able to reach us as they are traveling away just as fast as light. They out there on the other hand would kinda see the same thing of us time would stop as they are moving away to fast even though it would appear we are moving away to fast because everything is moving away from everything else all at the same time.
Siliskk t1_j9nii82 wrote
Makes sense, i hope we find more answers soon! Very captivating stuff
DudeWithAnAxeToGrind t1_j9npceg wrote
Those galaxies moving away from us are not moving through space. They are carried away by expanding space. That's a very important difference. A lot of this stuff applies only to things moving through space.
ptglj t1_j9nrvv1 wrote
We are "the edge of the expanding universe" from the perspective of the galaxies you are mentioning. Any given location in our universe looks like it's the center, so the edges of our own observable universe would not be experiencing anything different than ourselves.
Siliskk t1_j9nh507 wrote
Another thing to note is the interstellar movie, where on the planet 1 hour is 7 years on earth. If a civilization lived on a planet like this but opposite, where 1 hour on earth is 7 years on their planet, or perhaps more, it could be very likely
apple-pie2020 t1_j9nkovy wrote
It’s been a while since I saw the movie. I believe the one hour on the other planet created a +7 year earth time for the astronauts because an hour on that planet plus the trip home at near light speed was what caused the time. It’s a function that accounted for the delayed trip home and the travel at near light speed
[deleted] OP t1_j9npflu wrote
I think you may be misunderstanding the movie...(or I'm misunderstanding you...) There was no lightspeed travel. It was a wormhole. The time dilation was solely due to the proximity to the blackhole.
apple-pie2020 t1_j9owp0d wrote
Ok. It’s probably me. It’s been a good five years since I saw it. I’ll rewatch it, it was entertaining
DudeWithAnAxeToGrind t1_j9nrtvc wrote
It was very over exaggerated in the movie. The effect is real. There's time dilation due to both special relativity (the speed of satellite) and general relativity (how deep in the gravity well the satellite is).
The time dilation in the movie is so extreme, that I'm not sure a planet could even exist so close to the event horizon. There is such thing as innermost stable orbit around black hole; I wouldn't be surprised if for such extreme time dilation, a planet would need to orbit closer than innermost stable orbit (which would be impossible).
The clocks are slowed down by orbital speed, and also slowed down by how "deep" in gravity well they are. This means anything in orbit will experience its clock slowed down depending how fast it moves. Further away, the slower it moves, the less the clock in the satellite is slowed down compared to the surface of the body it orbits. However, the further away the satellite is, higher in the gravity well it is, and faster its clock ticks compared to the clock on the surface of the body it orbits. In case of Earth, there is an orbit where these two effects cancel each other. See this graph https://en.wikipedia.org/wiki/Gravitational_time_dilation#/media/File:Orbit_times.svg
DudeWithAnAxeToGrind t1_j9q4l6z wrote
Here's where somebody actually did the math:
TL;DR For such extreme time dilation, the planet would need to orbit just outside of photon sphere. There are no stable orbits that close to the event horizon; the planet would either fall into the black hole, or it'd be flung out into space.
The photon sphere is a sphere around the black hole where gravity is so extreme, photons are orbiting black hole in circles.
The black hole would need to be supermassive. Because anything smaller (e.g. solar mass black holes), the tidal forces that close to the event horizon would be so large, they'd shred the planet into tiny pieces... Or basically anything else, such as spaceship or a human.
For entire solar system to be so deep in the gravity well to experience time dilation as extreme as in the movie, and not be either destroyed or stripped of its planets, the black hole would need to be many orders of magnitude larger than anything we have ever observed. From what we know, no such black hole can exist. There was simply not enough time since Big Bang for any to grow that large, and due to the expansion of universe, no black hole will ever be able to grow to such a large size.
gucciglock92 t1_j9ni077 wrote
I've always wondered what the experience of an individual was when falling into a black hole past the event horizon. From their/its perspective would it seem as if space was expanding infinitely away from them as they fall further into the singularity?
Xanderak t1_j9nlmtg wrote
Not noticeably faster, but yes it’s possible that other planets may experience time a bit slower than us. Time slows down with lots of mass nearby (this is what causes gravity). So if another planet was orbiting near a neutron star, it’s time would go slightly slower relative to our point of view.
There is also relativity, where if the planet is moving away/towards us very fast, its time will be relatively slower. For the real mind trip, we’d also be going slower from their point of view!
There will be planets out there whose time goes eg 0.000000000000001% faster than us, because they have less nearby mass.
backwardog t1_j9niiit wrote
Side question: what would communication or observation look like?
I mean, between two planets experiencing a big difference in relativistic effects like this. If you were to try to observe, or communicate with, a planet where time is moving much faster using EM waves how would this play out exactly?
Standard-Meet5543 t1_j9nkpup wrote
I believe time dilation is significant only under very extreme gravity. I can't really vouch for how accurate Interstellar would be.... I would tend to think that a planet near a black hole where time dilation is strong just couldn't be compatible with life and I cannot imagine it surviving as a planet.
explodingladybugs t1_j9nl54n wrote
You're absolutely right, basic theory of relativity. Time is a construct of humans. Does the universe know what time is?
EntropicallyGrave t1_j9nl5c9 wrote
No; no - it's a much milder effect than that in all the relevant ways. Basically we're going as fast as possible - light speed, straight in to the future, relative to nearby, stationary, objects. When you provide a velocity, you need to specify what observer is measuring it; that is something we see immediately from relativity.
Everything moves at the same speed, in a certain sense - "c", we call it. That seems counterintuitive, but it isn't, if along with the rotations you can picture there is another dimension in which one might steer - or rather, steer away from. We could take some of our speed through time and exchange it for some speed through space. This is time dilation. It is one piece more complex than that, as we are really talking about imaginary time, here. But "imaginary" in the complex plane sense. Flipping our perspective so that linear motion in one direction represents translation in complex time is called a Wick rotation.
You're thinking in terms of gravity, and I'm answering with geometry; but they are equivalent descriptions.
If you could sit somewhere near our observational horizon - say, 13 bly away, or somehow protected and hauling around a black hole, then we would appear to slow greatly - but also we would be very redshifted, and it would be very hard to get back. So practically you can kind of ignore it; but there is something there, if you really really want to run the world ahead into the future a little faster, and you are allergic to anesthetics.
Limos42 t1_j9nlrgr wrote
OP, I think you'll appreciate this video by Dr Kipping (Cool Worlds channel on YouTube) that discusses time dilation via space travel.
Lots of very cool stuff in there to ponder! And his whole channel is a big rabbit hole. A gravity well so deep, you might even call it a black hole. 😏
Standard-Meet5543 t1_j9nlywk wrote
A planet could orbit a black hole like in interstellar, but I don't think time would be dilated on the planet. Time really wouldn't be dilated until you get very close to the black hole. I'm talking in generalities, I'm not really sure how far that distance would be. A planet orbiting a black hole wouldn't receive any heat or sunlight from the black hole, so I would imagine it would just be a cold world, not really hospitable to life.
AutomaticOrange4417 t1_j9nmar9 wrote
I've wondered this too are planets closer to the center of the galaxy, i.e. higher gravity, experiencing time slower than we are
[deleted] OP t1_j9no8ne wrote
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IndyJacksonTT t1_j9npnth wrote
Technically you’re right
Time does move slightly slower at your feet than your head for example
And slower in denser regions of space than less dense ones
psychonaut375 t1_j9nqwsq wrote
I have the same question from a diferent perspective. The more matter you have around you/the deeper you are in a gravity well (same thing), the slower time runs. This question asks about time on planets; I want to ask about time in the center of megagalactic voids. Time runs faster there than it does inside a cosmic thread of galaxies. So when I see a claim that the universe is 13.8 billion years old, I wonder how old it is depending on where you are. Has anyone seen a contour map of what time it is in the universe?
AnotherDreamer1024 t1_j9nqxp3 wrote
Just move away from any gravitational body, and the clock will speed up. There are some nice documenteries on atomic clocks put in aicraft and flown around for a few hours and then compared to their ground based brethren.
An even more up to date drift comparison is the ground based clocks used to keep the GPS satellite constellation atomic clocks aligned.
TheMiddleBoogerHook t1_j9ns69y wrote
Time has great influence on perspective.
Ive always wondered if time moved slower for flies than humans. So them buzzing around dodging my hand means I move slower by their perspective as if they are able to finish a conversation before moving out of the way.
Or whales move slow because they are big. But they feel time faster.
Scientists found that adrenaline changes perception of time... how time is perceived can be different.
I think time dilation is a real mechanism depending on location but most importantly, time is perspective by the observer.
So maybe if a planet on the outer rim of a galaxy, travelling slower, might be larger in size and gravity have more effect making them shorter and smaller. Maybe what feels like 30 minutes to us feels like 25 minutes to them simply because their size difference and chemical makeup inside whatever mechanism their body uses to perceive time.
A thought ive had since I was a child.
space-ModTeam t1_j9ns8km wrote
Hello u/Siliskk, your submission "Time dilation question" has been removed from r/space because:
- Such questions should be asked in the "All space questions" thread stickied at the top of the sub.
Please read the rules in the sidebar and check r/space for duplicate submissions before posting. If you have any questions about this removal please message the r/space moderators. Thank you.
cdRepoman75 t1_j9nk4ci wrote
Sure bud watever seems neato to you cuz thats all that really matters hail to you king of reddit and comprehender of time elsewhere !
Siliskk t1_j9nkwgf wrote
Dont need to be sarcastic, just asking a question based on science. Nothing wrong with learning, its all we really have in the end
Standard-Meet5543 t1_j9nl6zs wrote
Thank you for your thoughtful reply.
BeepBlipBlapBloop t1_j9ng91w wrote
Yes, it's very possible. You should read the book "Dragon's Egg". It deals with this exact idea.
Also, it's a great book.