What You Would SEE if You Traveled Near the SPEED of LIGHT

References:

Chapters:
0:00 - All light is basically the same
1:44 - Our slow-mo world
2:38 - Doppler effect
4:38 - How colors distort near speed of light
8:09 - Relativistic aberration (searchlight effect)
8:58 - Surprising time and length effects near c
09:05 - Things are NOT as they appear
13:58 - What is really true?

Summary:
All the light that we see are electromagnetic waves. All different wavelengths are equivalent, except that waves of higher frequencies are more energetic. The speed of all these EM waves, however, is the same. It's the maximum speed allowed in the universe.

This speed limit sets the max rate at which information can flow in the universe. This assures that causation is preserved. Einstein showed that the world would look very different as you near this speed. We don’t see this because our terrestrial speeds are very low compared to the speed of light.

What would happen if we traveled closer to the speed of light? Strange things.

When an ambulance approaches you, the wavefront made by its siren gets packed together towards the direction of movement. This causes a higher pitched sound. Similarly, the wavefronts get further apart in the opposite direction. This results in a lower frequency sound. This is the doppler effect.

Something similar happens with light. As seen from earth, most galaxies are redshifted, thus the wavelength is stretched. The galaxies are moving away from us. This is called the relativistic doppler effect, and it happens thanks to relativity. If we built a fast spaceship that traveled near the speed of light, this effect will change how you see the world compared to person who is not moving!

A red traffic light at 25% the speed of light we would be seen as green. If we moved away from the red light at 25% the speed of light, we wouldn't see it at all because it would be infrared, something our eyes can't see.

This also means that infrared light that we currently can't see in the cosmos would become visible in the front window of our spaceship.
Likewise, natural high energy ultraviolet light which is also invisible to us now, would become visible from our rear window. So we might see unexpected objects and colors both in front and in back our spaceship.

Another effect would be on the side window of the spaceship, called relativistic aberration, or the searchlight effect. From the side, you would not only see the colors distorted, but the light would appear brighter towards the direction of motion, and darker away from the direction of motion. This is because, if you are going very fast forward, then you are racing into more photons.

Special relativity also shows that time and length are also different for a moving observer, compared to a stationary one. At 60% the speed of light, time will slow down compared to a stationary observer, but you will not experience anything different. From your frame of reference, time will tick just like it does on earth.

1 meter for a stationary observer would only be 80 centimeters for the moving observer. This is called length contraction. This SHOULD mean that objects would look squished together. This is what’s happening, but NOT what you will see. Instead, you see objects curving away from you, and rotating towards you. The reason is because the photons from the front of the building are reaching your eyes earlier than the photons in the back of the building, so you see it curved. This is an optical illusion. the object in fact contracted.

This same effect means that spherical objects like earth don’t appear squished like a pancake, even though they are contracted, but remain spherical-looking. But they will appear rotated towards you.

This is again an optical illusion, because in reality the object is contracted. What you will experience is that distances are reduced, so a trip to Proxima Centauri, 4.5 light years away, will only be 3.6 light years.

The interesting thing is that even though things would be closer to you, they would actually look farther away when you viewed them from your front window. Likewise looking out the back window things will appear to be a lot closer.
#speedoflight
#specialrelativity
This seems to be a paradox, but as the spaceship moves faster, length contraction in the direction of motion means that objects on the side of the ship move towards the front. In fact, all the light from the side and even behind the ship would shift forward.

Your field of view increases in the direction of movement and decreases behind the spacecraft. Looking forward in the spacecraft would be like looking through a fisheye lens and looking out in the back would be like looking into a zoom lens.

[NTmatter]

There's a game called "A Slower Speed of Light" that simulates relativistic doppler shift, lorentz aberration, and length contraction. The speed of light is set to a brisk jog, allowing the player to explore a human-scale environment at light speed. It's a bit of a trip, but it might help to build an intuitive understanding of relativistic effects. Or, sign up for Brilliant :)

[paulwalsh]

As per usual, I knew about 80% of what was covered in this video from explanations I read for decades...
... but also as per usual, they were never explained so perfectly as when Arvin Ash does it in his videos !
Arvin has become one of the greatest popular science educators in my lifetime !

[felicityc]

There is a fantastic game the MIT lab made and released open source called A Slower Speed of Light. Because you really can't model what looking that fast would be like reasonably, it instead slows light down to show both the color shift as well as the 'latency' and looking forward but in the past.

Moving faster than all blue light is a very strange idea. Realizing the issue isn't going that fast but rather hitting slower things at that speed (tachyons) can reframe why moving so fast can be bad no matter what way you look at it, but I think messing around with the game can put the general theory into.

The demonstrated doppler effect with colors is incredibly beautiful. One could imagine how it might be perceived if our eyes had more concepts for a wider range of radiations.

[FaizanAli-opxe]

The fact that we can calculate how it would look when travelling closer to speed of light and use that info to create exact images using CGI is so cool and exciting. Great video. The amount of effort gone into making this video is appreciated.

[bhushan]

Saw video on similar topic on very popular channel but barely understand anything. Your explanation is very simple, even a kid can understand. Keep going!

[Roberto-REME]

Fantastic video, Arvin. You're the best. The time spent on this video's production is greatly appreciate.

[erwinmanzano]

Arvin,
I commend your elucidation in this video. I haven't watched any video as clear as you did explain. You answered my curiosity on how I would see the surrounding while traveling at light speed. Thanks a lot. You are awesome and gifted.

[Grandunifiedcelery]

Thank you for the easy-to-understand video and explanation😃
I felt like traveling in space in 2022🛸👽

[mohitsoni]

This was such a great question to answer.. Perspective on objective reality made me think about our mere existence again.. Thank you..

[InfinityAndParadox]

Arvin, so are you telling me that taking one hit of LSD is equivalent to traveling near the speed of light? 9:52 Ahahah, just kidding! Love your channel!

[jonathanhensley]

Issac arthur also explained like this video has by saying it the speed at which information can travel but we call it speed of light. Love how u make this topic easy for anyone to understand.

[haniamritdas]

Another question about light and expansion of space. When we see deep space, we are seeing the "distant past", the stuff that happened in our light cone. So when we "measure the expansion of space" and see acceleration, does it not mean that we are confirming that earlier inflationary period? I mean visually, we are not seeing that space is now expanding in all directions, we are seeing that it was expanding in the past. Anything happening "now" at a great distance away is not in our light cone, so there is no equivalent of the Hubble constant for present states of the distant universe. Those events are not in our light cone...???

[Eztoez]

One of the best physics video's I've seen in a long time. Well done, Arvin.

[mequavis]

lol, I love it, just posted on your last video like a day ago asking when the next video was coming out, and here it is lol

[hynesie]

When an explosion is big enough, dust becomes sentient and starts making YouTube videos.

[tomcato]

The frame at 3:50 Just Blew My mind
After many Years I finally understood what's redshifting of light
Thanks Man You Really Explained A Complex Question Simply with A Picture

[elmolewis]

Another well-done video. Thanks for putting out such high-quality videos.

[macronencer]

Brilliantly explained. I'm also pleased to have confirmation that I got things pretty much right in a short story I wrote about someone travelling at almost light speed :)

[florh]

Another lesson her should be hanging a warning sign on the front window like they do for rearview mirrors, "warning stars are closer to you than they appear when you're near light speed"

[Stroheim]

"Everything is relative", I said to my teacher in history of science. He (who was also a phycisist) corrected me: "Everything is relative -- except the speed of light!" And of course he was right, C is a universal constant. But now I wonder: Would there be any relativistic effects at all, if even the speed of light was relative? And if _nothing_ was relative, how should that universe looks like?