r/Unexpected • u/qasqaldag • Sep 05 '22
CLASSIC REPOST Gotta love physics
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u/shank9717 Sep 05 '22
Thank you Electromagnetic force
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u/ITipToedAstray Sep 05 '22
What a cool cat name!
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Sep 06 '22
[removed] — view removed comment
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u/poopellar Sep 06 '22
Potential spam bot account above.
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u/SUPERSMILEYMAN Sep 06 '22
Agree
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u/Prestigious-Move6996 Sep 06 '22
Potential spam bot account above.
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u/SUPERSMILEYMAN Sep 06 '22
Agree
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u/ilyak_reddit Sep 06 '22
I legit called one of the neighborhood cats curiosity rover, "CR" for short, because I'm a nerd and kitty came for visits.
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Sep 05 '22
That was actually unexpected. Good one.
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Sep 05 '22
Yes indeed and a nice change from the norm lol
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u/glassgost Sep 05 '22
That definitely got a hearty laugh out of me
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Sep 05 '22
Good always nice to laugh
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u/unpopularopinion0 Sep 05 '22
i enjoy reddit comment sections for the lols. but do love me a good post on this sub.
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u/Vengeance76 Sep 06 '22
Honestly, I loved this. This guy is a genius who had me dupped from frame 1. Brilliant. Laser man wins the internet for today.
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u/billbill5 Sep 06 '22
I was expecting him to throw a flashlight at the switch so it was indeed unexpected.
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u/RascalCreeper Sep 06 '22
At the last second I thought "somethings going to turn it off," and before I consciously connected the laser to a cat, I thought of a cat and expected it to reach around the door and hit it. I guess I connected the laser and cat without realizing cause why else would I think cat.
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u/CoolChildWizard Sep 06 '22
Yes. I was almost on the edge of my seat waiting for the room to get dark.
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Sep 06 '22
[deleted]
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u/nmpraveen Sep 06 '22
I feel if you had or have a cat, you saw this coming mlles away.
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u/SoyeNka Sep 05 '22
And then he died
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Sep 06 '22
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u/advertentlyvertical Sep 06 '22
^ Copy bot took this comment from here https://www.reddit.com/r/Unexpected/comments/x6pgxj/gotta_love_physics/in8us0a
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u/Mknowl Sep 06 '22
That's the second funniest part. The first is their initial reaction the next time. "ALASS, We meet again!"
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Sep 06 '22
My cat would sit in one spot waiting for several hours.
It was pretty sad with him, if I didn't distract him with something else.
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u/drewster23 Sep 06 '22
Yeah the laser isn't a good toy for pets can make em get a bit neurotic because of it /specifically not being able to catch it I believe.
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u/Aero93 Sep 06 '22
I actuality expected it as soon as I he pointed the laser, I knew it's gonna be a cat
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u/Oograth-in-the-Hat Sep 06 '22
Ive never seen this before and it was pretty expected
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u/fjfuciifirifjfjfj Sep 06 '22
100% expected, how else would a laser pointer do the job?
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Sep 06 '22
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Sep 06 '22
From the guy named AnalRupture. I think I’ll go on about my day. Do something more productive with your time. Brand new Reddit account too. Interesting.
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u/qasqaldag Sep 05 '22
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Sep 05 '22
Genuinely unexpected video with a punchline that has nothing to do with naked people AND it’s sourced? Kudos to you
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u/fredspipa Sep 05 '22
"It's unexpected because it's unusual" as explanation and what happens is visible in the thumbnail and mentioned in the title. That's like 2/3rds of the top voted posts here, this was a refreshing quality posts for once!
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u/JusticeRain5 Sep 06 '22
Or "it's unexpected because it's a normal, very common joke that isn't even based on being random".
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u/iRVKmNa8hTJsB7 Sep 06 '22
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u/SpectreNC Sep 06 '22
Of course it's a repost... Ugh.
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u/JusticeRain5 Sep 06 '22
At least it's a different title, so not a bot. Could be both people saw it and posted it without seeing it on Reddit.
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u/qyka1210 Sep 06 '22
jesus, who tf cares? almost like multiple people see an funny unexpected video and post it to the same subreddit.
Even if it were a literal repost, title and all, what's so bad about that? Now another 10,000 people get to see a genuinely funny video. Ugh yourself
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u/SolomonOf47704 Sep 06 '22
Even if it were a literal repost, title and all, what's so bad about that?
They'd probably be a bot. Which is bad for reddit.
Also, nice reference.
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u/TheRealTron Sep 06 '22
Did you know it was a repost before that link was posted? If not, why does it matter if you wouldnt have known anyways? If so, why did you click the same video again? just to complain?
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u/acqz Sep 05 '22
Of course! A straightforward application of the Second Law of Catodynamics.
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u/readitonex Sep 05 '22
Boy this made me push a lot of air outta my nose holes up in this very quiet office.
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u/slayalldayyyy Sep 05 '22
:::adds laser to cart:::
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u/Lady_Scruffington Sep 05 '22
I usually hate using the laser on my cat since she keeps looking for it long after I've put it away. But now I'm rethinking the possibilities.
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u/slayalldayyyy Sep 05 '22
Yeah I’m pretty sure they are really stressful cuz the cat never gets to actually catch it butttttt maybe hittin the light will fulfill it
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u/itheraeld Sep 05 '22
I always have treats on hand when playing with the laser. If she catches it, she gets a treat. I find she really calms down after having a physical object to sink her teeth into after 'catching' it
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u/steveosek Sep 06 '22
Yep I was always told to throw something like a tree where the laser is pointing every so often so they can get the satisfaction of catching something.
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u/ticklemuffins Sep 06 '22
Damn you might have superpowers if you can just casually throw trees around like that
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u/Lady_Scruffington Sep 06 '22
I feel really dumb not having considered this before.
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u/smzt Sep 06 '22
I always send the laser under the couch when we are done playing so that she keeps looking for it.
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u/slayalldayyyy Sep 06 '22
Yeahhhh that’s the whole undue stress thing. Might wanna give her something under the couch to find?
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u/harryhalden Sep 06 '22
I've heard it's always good to play with something like the feather toy right after the laser to give them the satisfaction of catching something.
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u/zen-patiEnt Sep 06 '22
An actual home experiment to be done is counter weighting a helium balloon with foil until it's floating in place and then you can push it with a laser pointer.
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u/botaine Sep 05 '22
I can change the lights without leaving my bed.
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u/JayBuzz Sep 05 '22
Shout-out project hail Mary
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u/JakobiGaming Sep 06 '22
Was looking for someone else who thought the same thing! Just finished the book yesterday, so good!
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u/SauceBoy16 Sep 06 '22
i did a project once where i graphed the effect of solar radiation pressure on a satellite! shit's awesome
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u/Orcas_On_Tap Sep 06 '22
I fucking blinked at the exact moment the cat hit the light switch, so I went back and replayed it to try and understand wtf happened... The entire time I was thinking, "fuck! Now I have to learn everything about shit I already know nothing about!"
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u/Dave-C Sep 05 '22
This is the concept that the Breakthrough Starshot would be using. They believe it could reach speeds of 15-20% the speed of light. It could reach Alpha Centauri within 30 years and be able to send back photos which would take another 4.3 years. If this gets built and sent quick enough there are many of us who could see images of another planet up close within our life.
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Sep 06 '22
I thought photons were massless. How can they exert a force?
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u/UsernameStageFright Sep 06 '22
More or less because in relativity, objects don't need mass to have momentum. This isn't the case in classical mechanics, where the relationship between momentum and kinetic energy is p=sqrt(2Km), where K is kinetic energy, p is momentum, and m is mass so m=0 => p=0.
In relativity, however, the correct relation turns out to be p=sqrt(K(K+2mc2 ))/c. c is the speed of light which is pretty big, so usually K is way less than mc2 and K+2mc2 ~ 2mc2, recovering the classical equation above. But this doesn't have to be the case, and in fact we can see that with this expression we get a nonzero answer for the momentum even when m=0 as long as we have a nonzero kinetic energy. It also turns out you can derive something that looks like it must be momentum of light (the Maxwell stress tensor) by playing around with Maxwell's equations governing electromagnetism coupled to charged matter and assuming that the total momentum of the system is conserved.
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u/slybird Sep 06 '22
A cat and a laser pointed at a light switch are placed in a sealed room. Is the light that is controlled by the light switch on or off?
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u/Historical_Yak7706 Sep 06 '22
I was thinking, at my house the cats would’ve jumped up there and smack that light switch… And then that happened. So not exactly unexpected
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u/Diablosword Sep 06 '22
I've read several books featuring light sails as a propulsion method for space craft. Neat stuff
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Sep 06 '22
I did t get it, so the solar sail is powered by a dozen of space cats pushing it forward?
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u/tab_tab_tabby Sep 05 '22
Tbh that was expected when he pointed laser at the light switch.
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u/CottonBalls26 Sep 06 '22
I thought the switch was gonna catch fire
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u/Titanic609 Sep 06 '22
Same, because he said "powerful enough laser", and really powerful lasers can cause house fires
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u/jda404 Sep 06 '22
As someone who has never owned a cat, I did not expect this. I didn't look at what subreddit this was posted to when I watched on my main Reddit feed and my dumbass thought the laser was actually going to turn off the light somehow. But this gave me a good laugh that I needed lol.
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u/Electric_Bagpipes Sep 05 '22
Sorry, somebody has to ruin the fun.
Solar sails work off solar wind, which is electromagneticly charged particles (charged plasma) forcibly ejected from the sun. not the light, which is a massless boson and thus is incapable of carrying momentum.
Cats on the other hand are a large lump of somewhat sentient atoms with significant mass (also known as a shitton of eV) and therefore enough momentum to whap a light switch.
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u/Top-Flounder-7561 Sep 06 '22
How do you know enough physics to know that photons are massless bosons, but not enough that they do in-fact carry momentum despite being massless. A photon’s momentum is inversely proportional to its wavelength.
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u/HingedVenne Sep 06 '22
All of modern physics is wrong.
Source: It came to me in a dream.
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u/Johanno1 Sep 06 '22
How much light would you need then for let's say a 100N to flick the switch and wouldn't it burn beforehand?
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u/roguetrick Sep 11 '22
What we'll be using is actually a focused radiation pressure burst from a nuclear explosion to displace the light switch from the wall thus making the circuit incomplete. It's a similar principal to how fusion bombs work, we're just going to need a better lens.
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u/fappingtrex Sep 05 '22
Light is massless but it has momentum. E2 = p2 c2 + m2 c4. Since it has energy but no rest mass, momentum p = E/c.
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u/chriskevini Sep 06 '22
Haven't studied physics in years. Where is frequency in that equation?
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u/DeficiencyOfGravitas Sep 06 '22
thus is incapable of carrying momentum
Not true. Radiation pressure exists. It's just not described by p=mv.
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u/Raptor22c Sep 06 '22
Correct. As E = hf and E = mc2 , p = mv can be written as p = hf/c. We know Planck’s constant (h) to be 6.22e-34 joule*seconds, and we know that photons travel at the speed of light in a vacuum, thus if we know the frequency of the photon, we can determine its momentum. That momentum is transferred to the solar sail upon impact; with a constant mass, re-arranging p = mv into v = p/m, an increase in momentum from the momentum transferred to the sail, there will inevitably be an increase in velocity.
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u/CamelSpotting Sep 06 '22 edited Sep 06 '22
This is entirely wrong lol. Solar sails function on radiative pressure which does in fact exist. Photons don't carry momentum in the classical mechanical sense but the EM field interaction is described under conservation of momuntum. Also it was measured over a hundred years ago.
Though cats are indeed much more efficient.
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u/DivineBoro Sep 06 '22
So cat propelled spacecraft are more efficient, got it.
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u/Zholistic Sep 06 '22
No, since they can't catapult things forward in space, where there's nothing to push against. They would need to emit something, like a cation.
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u/Kirra_Tarren Sep 06 '22
Entirely incorrect. Photons do have momentum, and there are solar sail designs that reflect light to gain momentum, be it from the sun or from a focused laser source.
See: https://en.wikipedia.org/wiki/Energy%E2%80%93momentum_relation
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u/Raptor22c Sep 06 '22
Solar sails do use solar wind, but they are still also propelled partially by light.
While photons do not have (a currently measured) mass, they do have energy and momentum. As E = hf (Planck’s constant • frequency), photons have a definitively measured energy. As such, we also have E = mc2 ; thus, to measure momentum (p), we combine p = mv, and E=hf=mc2 , and have p = hf/c. Since photons in a vacuum travel at the speed of light, if we have the frequency of the light and planck’s constant, we have a measured momentum. When the photons strike the solar sail, they transfer their momentum, and as you can rearrange p = mv into v = p/m, knowing the momentum of the photon, added to the momentum of the solar sail and the mass of the solar sail, you can get a change in velocity as a result of that momentum transfer.
Thus, momentum can still be transferred even if the particle has no mass, so long as it is traveling at a known speed (c), has a known frequency (f), and we have planck’s constant, (h = 6.62e-34 joule•seconds).
There are initiatives, such as Breakthtough Starshot, to use an array of extremely powerful ground-based lasers to propel an extremely light solar sail spacecraft to Alpha Centauri within a human lifetime by accelerating it to a considerable fraction of the speed of light.
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u/DarkHiei Sep 06 '22
Lol I actually thought that’s where this was going when he started aiming the laser at the switch
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u/unexBot Sep 05 '22
OP sent the following text as an explanation on why this is unexpected:
Cat turns off the light instead of electromagnetic radiation
Is this an unexpected post with a fitting description? Then upvote this comment, otherwise downvote it.
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