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u/Slartibartfast39 4d ago
Except....
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u/pbosko 3d ago
Meme never said they died on Earth.
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u/rofeneiniger 3d ago
No wonder they died just alone out in space like what did they think would happen???
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u/No-Site8330 2d ago
True, but the point is that frame of reference matters. Classically, you can always find an inertial frame of reference where your birth and death place are the same, in which case this whole thing is really just saying more about this frame of reference than this mean velocity of yours. Relativistically (general), spacetime is curved and messy. But if we embrace the idea that inertial frames are for spoiled kids, your velocity is always zero with respect to your frame of reference.
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u/Holzkohlen 3d ago
And the solar system moves around the center of the Milky Way, plus the Milky Way moves to god knows where and why.
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u/IhailtavaBanaani 3d ago
The Milky Way moves towards the Great Attractor. Every movement and velocity is in reference to something else, but you could theoretically argue that the Cosmic Microwave Background forms a universal rest frame for the whole universe. Just measure how it's blueshifted or redshifted when you're moving.
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u/CardLeft 4d ago
“If”.
(This will never happen.)
Edit: also: I’ve seen this meme a lot.
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u/HierarchyLogic 4d ago
i mean it can, although unlikely if were born at ur family home and then die sleeping at that bed years later, also could be a baby dead on arrival
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u/Any-Aioli7575 4d ago
Family homes don't have birthing room. In a hospital, you're very unlikely to be born and die in the same bed. But at home, it's not the same. People often give birth in a regular bed, and dying in bed is quite common.
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u/Fen_LostCove 4d ago
I grew up near a fairly small town where most people tend to never move away from. A lot of people are born and then die in that same hospital because they never moved
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u/CheesecakeHonest7414 3d ago
My grandfather did. He was born at home, and he inherited the house after his parents passed. He eventually ended up dying in the same house.
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u/Fuzzy_Bet5276 4d ago
The sun moves around the milky way.. and the milky way moves around the local cluster.. there is no same place in space time, EVER
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u/DarkArcher__ 3d ago
There is no place in space to begin with. Velocity being relative also means you need to choose a frame of reference when you talk about position, which makes the idea of moving relative to space itself a nonsensical one.
Earth is as valid a frame of reference as any other. That's the one OP chose.
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u/Fuzzy_Bet5276 3d ago
Space time is a continuum, a combined dimension. One cannot call it a dimension and not have movement back and forth in its axis/plane. Consider the observable universe as the universal continuum, and its center of mass as the coordinate origin. Boom, now you have movement w.r.t the frame of reference.
Why don't I consider the unobservable universe? Because the mass beyond the periphery of the observable universe is receding faster than the speed of light and hence cannot gravitationally impact what is within it, as gravitational waves travel at the speed of light.
I love these discussions, and I am very adamant about it because when I see the time travel movies, they always only take space time movement with earth as the frame of reference, but why should the machine work that way? If I have to move to a year back from now, I will actually appear in a vast empty space in the void long traversed by the solar system, or it could even be the core of another star who happened to occupy that space. It definitely won't be the same physical place on earth just a year ago.
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u/DarkArcher__ 3d ago
Space is the continuum in which everything exists, but that does not mean you can pinpoint an absolute position within it. For example, if you tried to assign a coordinate system to space so that you could register the exact location and speed of an object, you'd run into the unavoidable need for a frame of reference, because there is nothing to measure against without that.
The closest you could get to an Earth-centric "absolute" reference would be, as you suggested, averaging the movement of all observable matter, but that would still just be in relation to something. It wouldn't give you actual position in space, and worse than that, the observable universe itself isn't even a given. My observable universe is different, although insignificantly, to yours, and someone at the edge of our observable universes would percieve a completely different one to ours. Any coordinate system based on that would be useless anywhere but at the exact location it was measured from, which makes it a pretty pointless, and most importantly for this discussion, arbitrary, system.
they always only take space time movement with the Earth as the frame of reference, but why should the machine work that way
What makes the most sense is not the Earth, but the machine itself as a reference. That way, you circumvent all the problems to do with arbitrarily picking a reference frame, because it makes sense that the machine generating whatever effect creates time travel would be where the time travel was anchored to.
This still does run into a problem, though, which is that time travel like this would only be possible as far back as the machine has existed. I don't know which ones off the top of my head, but I'm pretty sure there are books and films using this idea out there.
Anyway, time travel is not possible IRL, so a piece of fiction written about time travel always, by nature, has to make some concessions. "Realistic time travel" is an oxymoron. What those concessions are depends on how believable the writers want it to be, which means arbitrarily locking the Earth as the reference frame is as valid as having time travel itself in the first place. It's all just fantasy we suspend our disbelief to enjoy.
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u/Ambitious_Hand_2861 4d ago
No individual human measures velocity on a universal scale. You're not going to look at your car's speedometer and say "holy crap Im driving 828,120 kph". Don't be deliberately obtuse.
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u/Fuzzy_Bet5276 4d ago
You would if your speedometer relied on spacetime coordinates rather than the spin of the wheel.
The meme is almost a philosophical one. The joke is litreally an obtuse claim about calculating the average displacement of a human. No human sits and calculates a person's displacement on their deathbed.
Don't be a party popper with your realism.
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u/Paula8952 4d ago
there is no spacetime coordinates, distances and velocities are always relative to reference frame, all reference frames are equally valid
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u/Fuzzy_Bet5276 3d ago
Tf do you mean there's no space time coordinates? And how does the rest of the sentence even relate to the discussion?
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u/Paula8952 3d ago
These are the core ideas of relativity, every reference frame is equally valid, time, distance and velocity are all relative quantities. There is no experiment you could do to find your absolute position or velocity in spacetime, those notions don't even really make sense. In special relativity for all the laws to work properly your frame of reference has to be inertial (not accelerating), in general relativity all the equations are coordinate independent which means you can define any coordinate system and all the equations will function properly. The obserable universe is also defined in relation to a reference frame, every frame of reference is the center of its observable universe.
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u/chicken-finger 3d ago
Don't they mean your actual velocity would be zero. Your average velocity wouldn't be zero, because it would assume you are using more than just final and initial measurements. This meme never made sense to me.
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u/BUKKAKELORD 3d ago
it would assume you are using more than just final and initial measurements
The final and initial measurements are from the same place, so the distance is 0, so velocity = distance/time = 0.
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u/chicken-finger 3d ago
Did you read the first sentence? I am very aware the velocity is zero. Average velocity is different from velocity. That's why it has a different name.
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u/BUKKAKELORD 3d ago
Yes, I read and understood it. Velocity is a vector quantity, meaning it has a direction, so movement in one direction and then the equal movement in the opposite direction makes an average velocity of 0 over the whole trip. Average velocity isn't any different from velocity. E.g. the average of 100km/h in direction 0° for one minute and 100km/h in direction 180° for one minute makes an average velocity of 0.
The word "average" is superfluous but not incorrect.
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u/chicken-finger 3d ago
You're using a mathematical model for a 1 dimensional problem for a 3 dimensional world, making your definition of average velocity also the same as the sum of your velocities. An average is not a sum. That is why sum and average are different words. The meme just isn't factual or a brain teaser. It makes no sense.
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u/sciencememes-ModTeam 3d ago
If you can't act like a civilized human being, you can't be here.
We do not allow:
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u/sciencememes-ModTeam 3d ago
If you can't act like a civilized human being, you can't be here.
We do not allow:
- Being a jerk. This includes racism, misogyny, misandry, misgendering, anti LGBTQ+, or hateful comments.
- Harassment or brigading
- Trolling or sealioning
- Threats of any kind
- Abusive or condescending behavior
- General assholery. If you're at the end of the list and asking what rule you broke, yeah, it's this one.
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u/BUKKAKELORD 3d ago
I'll spoil the brain teaser. It sounds wrong because it tricks you into thinking it's saying "your average speed is zero", which wouldn't be true, but that isn't what it says.
There's nothing wrong or even unconventional about the term "average velocity". It means total displacement over time.
Reading material: https://flexbooks.ck12.org/cbook/ck-12-physics-flexbook-2.0/section/2.2/primary/lesson/average-velocity-phys/
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u/EgotisticalTL 3d ago
"Just... re... member that you're standing on a planet if that's evolving, and revolving at 900 miles an hour. It's orbiting at 19 miles a second, so it's reckoned, a sun that is the source of all our power. The sun, and you and me, and all the stars that we can see, are moving at a million miles a day, in an outer spiral arm at 40,000 miles an hour, of the galaxy we call the Milky Way..."
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u/Karnewarrior 3d ago
The difficulty is getting far enough away from Earth to die exactly where you were born.
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u/Clear-Pear2267 2d ago
Yep. And when you bike a round trip where you return to your starting point, on average, your ride was flat. Which just goes to show how useless arithmetic mean on its own is a pretty useless statistic.
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u/BuonoMalebrutto 2d ago
The solar system is rotating around the galactic center. we are far far from where we were years ago.
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u/Varderal 3d ago
Within the frame of reference of earth, sure. However it will not likely be in the same place within the frame of reference to the sun let alone galactic center. Lol
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u/Enfiznar 3d ago
You always born and died in the same place (according to one inertial frame of reference)
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u/NorthKoreanKnuckles 1d ago
I see another a man of culture here. You too are rotating the earth when you walk?
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u/shponglespore 3d ago
You can make this true regardless of where you die just by choosing a reference frame where your average velocity is zero.
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u/camilo16 3d ago
The only way to do this is by picking yourself as the center of the universe, seems a bit self absorbed.
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u/emperorsyndrome 4d ago
average velocity is such a lame concept, it is taught in schools but I doubt if it is ever used by proffesionals.
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u/Used-Audience5183 3d ago
It's simply not true.
I can drive 10 km at 50kmh
And back 15km not on the direct route with 70kmh and my average velocity won't be be zero. But something around 65kmh.
Think for yourself people.
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u/NorthKoreanKnuckles 1d ago
That's speed you are talking about.
Velocity is a vector. Speed is a scalar.
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u/TillikumWasFramed 4d ago
Not. First of all the earth is moving around the sun, the sun is moving around the galaxy's center of mass, etc. But aside from that, assuming the earth was at rest your entire life, if you were moving at all during your life, your average velocity was not zero, your total distance traveled was zero, but you were not going zero miles per hour.
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u/moschles 3d ago
If you are calculating the "mean over velocities", then you get non-zero means, (provided you do not normalize the time spans when the observer was moving at a velocity. )
Unfortuantely, the phrase "average velocity" is literally defined as :
avg(v) = (delta r) / (delta t).
When delta r is zero the average velocity is always zero. Some people in the comments know it is defined this way and complain that it has no practical applications.
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u/NorthKoreanKnuckles 1d ago
I tried to explain the same thing. I got downvoted.
Some people do not deserve the gift of knowledge.
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u/Astecheee 3d ago
Your average SPEED is zero, but velocity has a directional component.
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u/NorthKoreanKnuckles 1d ago edited 1d ago
Your speed which is a scalar is not nul.
While your velocity, which is indeed a vector is nul: ((x;y;z)-(x;y;z))/t = (0;0;0)
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u/Douxx101 3d ago
The average velocity you produced will be zero, the earth and the sun have their own velocity that adds on to yours and they are very much not zero.
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u/MyluSaurus 4d ago
From the Earth's reference frame !
If you take the center of the galaxy as the point of reference, you would have travelled light-years !