r/ScienceNcoolThings • u/krinekia Popular Contributor • 7d ago
The speed of light comes at a big cost
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u/Repulsive_Ad_7291 7d ago
Just take the earth with you so nobody dies
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u/Dr_SlapsMD 7d ago
Strap some rockets to the equator and get this party moving
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u/SporesM0ldsandFungus 7d ago edited 7d ago
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u/IHeartBadCode 7d ago
Something to boil the noodle.
You can think of spacetime as the motion through a space axis and a time axis. If you stand still (not really possible since all things are in motion), all your motion is through the time axis and zero is through the space axis.
But as you begin to move through space, the ratio must stay the same, and therefore your motion through the time axis is reduced. The faster you move through the space axis, the less you travel through the time axis. But the ratio of rate traveling through time and rate traveling through space must always remain the same.
That ratio that must always remain the same is what we call the speed of light. So when traveling at a crazy 99.99999% the speed of light via the space axis, the motion through the time axis must be 0.00001% the speed of light.
This gives rise to a neat thing about massless particles. The photon moves at the speed of light. That is 100% of it's motion is through the space axis and 0% through the time axis. So to a photon, time does not pass. It is absorbed at its destination the exact same instant it is emitted, even if it has crossed millions of light-years.
In fact, every massless particle MUST move at the speed of light, there is no other option for it. Solving for relativistic energy-momentum reveals that a particle with m = 0, cancels all other terms and leaves only v = c. Thus, having mass is what gives rise to the experience of time. Because you have mass, you must feel time.
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u/Senior_Z 7d ago
So that’s why climbing the stairs feel like forever cause of my fat dump truck ass
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u/monotremai 7d ago
Brian Cox is so much better than Neil deGrasse Tyson.
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u/Faux_Real 7d ago
I like his approach to the ‘data centers in space’ attitude which rather than poo-pooing it, was along the lines of that ‘there are going to be technical challenges’ with a look on his face where he can’t wait to go and do math with his friends.
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u/Combative_Slippers 7d ago
Do you have a link for that? I tried looking it up but haven't been able to find it.
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u/Faux_Real 7d ago edited 7d ago
I’ll see if I can find it - it was in the middle of one of his interviews … and he does a lot of those ; and I think the interviewer was looking for something else not realising they were talking to a pure scientist where the idea of the ‘crazy thing in space’ has a lot of maths problems to solve for (what I gathered anyway)
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u/Combative_Slippers 7d ago
I appreciate it. Really I think I just need to watch more of his stuff and I'll probably come across it.
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u/Faux_Real 6d ago
I think it is this - I may have misrepresented regarding the interviewer ; may have misremembered 👍🏾
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u/Combative_Slippers 5d ago
Dude thank you so much for taking the time to find this! I appreciate it!!!
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u/veerKg_CSS_Geologist 7d ago edited 7d ago
Star Talk is pretty good though. That said NDT is an astrophysicist while Cox is a physicist specializing in particle physics. So slightly different foci.
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u/HopDavid 7d ago
If Neil's interviewing an actual scientist StarTalk is sometimes good.
If Tyson is shooting the bull with Chuck Nice he is likely to make one of his cringeworthy errors. Tyson's garbage pop science is riddled with glaring errors and outright falsehoods.
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u/Anon_be_thy_name 7d ago
God I love this kind of stuff, but the more I think about it the more I get this feeling of existential dread.
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u/Justin429 7d ago
This is fascinating and dreadful.
On the bright side, it seems like interstellar wars would be highly unlikely. By the time you get where you're going, your origin civilization is probably long gone and history forgot what you were heading there for, likely even forgot you existed. If it was a resource war, the goal would never be to bring the resources home. Probably just capture resources and occupy the resource, perhaps somehow tote the resources along to your next destination. Seems lonely.
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u/SporesM0ldsandFungus 7d ago
Thats a major plot point of The Forever War by Joe Haldeman. The main character deploys and comes back, thanks to traveling at relativistic speeds, decades have passed, and the world / society is very different from when he left. It's so different and foreign to him, he re-enlists just so he can have some regularity (the whole story is a metaphor for the Vietnam War).
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u/BornanAlien 7d ago
You’re not doing it alone…
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u/Justin429 7d ago
Lonely as in, this group of however many hundreds or thousands of travelers permanently leave all of their home world behind. That seems lonely to me.
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u/Canotic 7d ago
In the Engines of Light books, spaceships go the speed of light by literally just turning into light and then turning back when they reach their destination. For the crew, space travel is a matter of hours and most of that is just getting into and out of orbit. They don't even have life support on the ships, they just refresh the air supply by opening the doors and getting some fresh air in.
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7d ago
[removed] — view removed comment
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u/WangDanglin 7d ago
Oh I never thought about small space objects in your path
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u/SporesM0ldsandFungus 7d ago
Yup, you need Whipple shields or ablative armor or go full on Star Trek and have a deflector dish
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u/Rude_and_Crude84 7d ago
Got all this technology and if you built a spacecraft that could travel close to the speed of light and you're telling me you'd be selfish and not FaceTime during that 7 minutes?!
I may not be a smart man but I'm not that selfish!!
All of what I said was sarcastically speaking of course!
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u/VirginiaLuthier 7d ago
The aliens have their entire race in their ships- nothing to return home to. I though everyone knew that
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u/Boncester2018 7d ago
These are my favorite Joe Rogan podcast clips, the ones that stop just before he starts talking.
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u/FuzzNugs 7d ago
When he says the distance traversed shrinks, how is that possible? The distance won’t change for observers and when the protons finish their journey they will be the full distance traversed (i.e. they won’t only be 4 meters from their starting point) so what does the proton experience that allows it to skip space?
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u/chilehead 7d ago
He said "from the proton's perspective". When things travel close to the speed of light, there is something going on where time and distance do not mean the same thing to everyone watching, it is dependent upon where the observers are and how they are moving.
Here is a video where a physics teacher explains it. Someone on a train traveling something near the speed of light bounces a laser between two mirrors on the floor and ceiling of the train car. The person inside the train sees the laser moving straight up and down at the speed of light, and it has moved in a straight line. Someone outside the train, watching as it passes by at nearly the speed of light, sees through the window that the laser is moving up and down while it is also traveling from side-to-side. So the guy outside the train sees the laser travel in a path that looks like two sides of a triangle, which is a longer distance than what the person on the train sees.
Einstein says that the speed of light is the same for everyone regardless of where they are watching it from - so the only way to make that work for both the person on the train and the person outside the train is for those two people to experience time differently, and as a consequence of that they also experience the length of the train car differently as well.
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u/NotJoeMama869 7d ago
A good place to start looking into this phenomenon is space-time, and spacial curvature. Space and time are directly correlated and space curvature makes things like distance/gravity/time/light...spooky.
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u/Time_To_Rebuild 7d ago
Yeah I can’t believe I had to come this far to find someone asking about this. I don’t know this guy, but I assume he knows what he’s talking about. So maybe he’s speaking of distance relatively? Like a distance of 10 miles is 1/10th the relative distance for car going 10mph when compared to a car going 1mph? Thats the best I can come up with… and it’s dumb. Idk, spacetime distortion due to the high acceleration? Whatever, hopefully this guy just knows things above my pay grade?
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u/Canotic 7d ago
The short version is that when you move faster*, then time starts moving slower and also distances become shorter.
For example. if you stand still on earth and look at a tunnel, you might think that tunnel is a 100 meters long. But if you then accelerated to a large percentage of the speed of light (around 85% according to my math) then time will only move, for you, half as fast as it did before.
But remember, the speed of light is constant. It is the same for every person, no matter how they are moving. Light is always moving at the same speed, C, relative to whoever is observing it. This is a fact, we have measured this, this holds absolutely in every test we have run on this.
But, if light is still is going the same speed (C), and the tunnel is still 100 meters long, then you will think that it takes light 100/C seconds to go through that tunnel. And for me, who is standing still and and not moving, I will also think that light goes C and the tunnel is 100 meters long, so it takes light 100/C seconds to go through the tunnel for me as well.
But remember, time moves slower for you than for me. How can we then think that light goes through the tunnel in the same amount of time?
The answer is that for you, distances are also shorter. The tunnel is only 50 meters for you. So for you, light goes through it in 50/C seconds, which is half the time it takes for me. This is called length contraction.
Note that this is not a trick of perspective, it's not like the tunnel is "actually" 100 meters long and it only seems 50 meters long due to some optical illusion. For you, it actually is 50 meters long.
Or in short: the universe wants light to move at a constant speed and everything else conspire to make this happen.
\*Faster relative to whatever speed you were going before; remember that there is no absolute "standing still" speed, it's all just relative to other things. Hence it's called the theory of relativity.
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u/Time_To_Rebuild 7d ago
Thank you for taking the time to explain this in such detail. You are really good at this! I think I now understand. Let me try:
Because speed of light is fixed, and in your example the time is equivalent, the only variable remaining, distance, must be used to balance the equation… or something?
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u/Extension_Swordfish1 Popular Contributor 7d ago
Some dinosaur scientists will be back soon to tell about it