You Are Traveling at the Speed of Light Right Now

You've probably heard the rule that you cannot travel faster than the speed of light (in a vacuum). And this is true.
You may also have heard that you cannot travel precisely AT the speed of light. But this is false...because you are, in fact, ALWAYS traveling at c. Good ol' Relativity can explain why.

Hosted by: Stefan Chin (he/him)
----------
Support us for $8/month on Patreon and keep SciShow going!
Join our SciShow email list to get the latest news and highlights:
----------
Huge thanks go to the following Patreon supporters for helping us keep SciShow free for everyone forever: Reed Spilmann, Odditeas , Garrett Galloway, Friso, DrakoEsper , Kenny Wilson, Lyndsay Brown, Jeremy Mattern, Jaap Westera, Rizwan Kassim, Harrison Mills, Jeffrey Mckishen, Matt Curls, Eric Jensen, Chris Mackey, Adam Brainard, Ash, Piya Shedden, charles george, Alex Hackman, Kevin Knupp, Chris Peters, Kevin Bealer, Jason A Saslow
----------
Looking for SciShow elsewhere on the internet?

#SciShow #science #education #learning #complexly
----------

[MeltiahNye]

That's the best, most easily understood explanation of relativity I've ever heard. Excellent job, SciShow!

[generalZee]

"I'm sorry, officer, it is physically impossible for me to go slower than the speed of light."

[BrackenStrike]

Had this exact conversation in Physics 2. I asked my professor if there was such a thing as a rate of travel through time and he disagreed with me because he didn't think there were units that could describe such a thing. I'm like, "dude, the universe doesn't even care if we have the units figured out."

[EpicGracification]

You had so much fun telling us all were wrong halfway through our answer 🤣 love it

[poshrat]

Awful thing to say to someone who’s panic high

[bballplayer]

It does not slow down… it excites and de-excites in the electron clouds of atoms and that creates a latency or delay that depends of the relaxation time of excited vibrational states of the electrons.

[ariadgaia]

Ugh... I shouldn't have clicked on this one... It's definitely interesting!! But listening to just the first 2:39 of this video has me nauseous from 😢

[hacked]

Glad to see this video reaching the masses. Most people haven't thought this through to understand it

[personwithcommonname]

You know when you're having a really bad week, and your brain hurts super easily and Murphy's law seems to have somehow gotten mixed up with Twitter to produce the most hateful things you've ever read and making you fear how much evil is in the world?

And then your best friend comes over, and says 'check this out, it's so cool!' and instead of a nice simple pun or fun analysis of which dinosaur pooped the most, they start talking about relativity, the speed of light, relative motion, space time, and the time dilation side effect and then they REALLY get going.
I love you SciShow but you're making my head hurt so much and giving me existential dread!

[donaldolin]

Constantly violating the speed limits on my bicycle here.

[Kalaphant]

The history lesson from 2:45 to 6:30 is giving me Speedrun WR Progression vibes and I love it.
(Especially 5:20-6:30)

[Zebred]

Elsewhere I've heard it said by physicists that c is more correctly the speed of causality.

[eloihomier]

Definitely one of the best explanations of the concept I've seen. Thank you!

[matthuber]

I was scoffed at for postulating this to someone long ago, so this is validating. Thanks!

[bosslca]

My thought experiment for this is to define three frames of reference. First to fire a photon/lightwave along a vector/numberline X starting from X=0. This is reference 1. From a Stationary perspective, reference 0, the Lightwave is moving some speed in a postive X direction. The Lightwave arguably can view itself traveling in a positive X direction. That Lightwave, immediately once fired, fires it's own Lightwave behind itself, creating reference 2, in the X vector in a negative X direction. So from the stationary reference 0, Lightwave 1 is traveling +X and Lightwave 2 is traveling -X. From Lightwave 1's perspective while traveling positive, Lightwave 2 is at X=0. And from Lightwave 2's perspective while traveling negative, Lightwave 1 is at X=0.

As such, the only way to rectify how both photons can 'see' the other as stationary is to apply time dilation to such a degree that time has effectively 'stopped' for the other in their perspective.

In other words, Photons travelling at the speed of light do not 'age' in reference to other Photons.

So I ask the question. From the persepective of itself, does a Photon age? and if so, what does it experience? Does it travel to the infinite 'end' of the X vector in one infantesimially small duration of time? A photon from a distant star travels a vacant path till it happens to excite an electron in the cluster of mass that is a Human eye in a degree of time? If a Photon does not 'age', then the distance between the star and the human eye is a non-factor and from a photon's perspective, we still exist inside the singularity?

[Nysyarc]

This really helps to understand why photons don't "experience" time so to speak. For anything, like a photon, to travel only through the 3 dimensions of space at a velocity of C, it must necessarily have a speed of 0 in the time dimension. It may take around 10 minutes from our perspective for a photon to reach us from the Sun, but to the photon the trip is instantaneous, along with all the rest of its entire existence. A difficult concept to make sense of, but thinking of it in terms of C being a value that is distributed amongst the 4 dimensions of spacetime, and photons allocating 100% of that value to only the 3 dimensions of space makes it a bit easier to understand.

When we are at rest in space, we are moving through time at the fastest rate possible. When a photon is moving through space at the fastest rate possible, it is at rest in time, i.e. not moving through time at all.

[John_a_Technocrat]

There is a very large problem with this that I see people making. Consider the following.

If a spacecraft sitting on Earth instantly leaves Earth travelling at 99% the speed of light away from Earth for about 6 months and then instantly reversed direction to come back to the same spot on Earth approximately 6 months in return time, then stopped at the starting point on Earth, the amount of time that past on the spacecraft will have been significantly slower than the time that past on Earth. Thus about 1 year will have past on Earth where as about 14% of 1 year will have past on the spacecraft.

But, if this is truly all relative, the the spacecraft can say it is the one standing still and not moving. So the Earth is the one which moved at 99% the speed of light for 6 months in one direction then 6 months coming back, thus about 14% of 1 year will have past on the Earth while 1 year past on the spacecraft.

See any problem with this?

[TragoudistrosMPH]

This was really well explained! I'm in that knowledge bliss state, right now, thanks to your team!!! ❤️‍🔥
Amazing usage of those equations and graphics, script, and presentation!

[samuela-aegisdottir]

I have heard that c is in fact not the speed of light but the speed of causality. Everything moves by the speed of causality. It is also a maximum speed one object can influence other accross some distance. And only light in vacuum can travel by this maximum speed through space.

[cheifDeisel]

This video didn't help get me out of my speeding ticket but it was still informative so thanks, I guess.