What would we see at the speed of light?
Why Physics Stack Exchange recommends it
Physics Stack Exchange users link it when asking about relativistic visual effects such as light aberration, and as a reference animation of what an accelerating observer sees.
Recommended by 1 people across 1 different months, 2023 to 2025.
What it is
A 15-minute animated explainer from ScienceClic English, narrated by Octave Masson, on what an observer would see while accelerating toward the speed of light. It covers aberration of light, the Doppler effect, time dilation, length contraction, the light-speed limit and a brief look at warp drives.
What people said
Recommends user9343456 · 2023-04 · Physics Stack Exchange · on “How would we perceive a pulse of light if we accelerated constantly in the same direction?”
I'm watching this video [this video] (the link starts at the relevant timestamp) and am confused about one thing. Let's say I'm going at a constant speed of $0.99c$ in $+x$ direction (w.r.t Earth), and a pulse of light is also moving in the same direction. Of course, I'd see the pulse moving away from me at $c$ , since I'm in an inertial frame. But let's say I'm accelerating with some constant acceleration $a$ - my own speed will approach $c$ but never reach it, but in this scenario, how would I perceive the pulse of light? Will I still see it as moving away from me at speed $c$ ? For me, can I say that for an infinitesimal duration $dt$ (duration measured in my frame), I'm in one inertial refere
Cites user6760 · 2024-01 · Physics Stack Exchange · on “Is there aberration of sound?”
I watched a [this video] by Scienclic showing a spaceship experiencing a peculiar optical illusion when going faster and faster in space, I wonder is there a version for the sound? Like I'm driving faster and faster on a busy traffic then I think most of the sound are coming from ahead despite the sources are actually at the sides?
Cites Last American Hero · 2024-11 · Physics Stack Exchange · on “Does an uniform rod hinged at the center rotate when released from any angle?”
It depends on the specific details of the gravitational field and the observers. If the field is perfectly uniform and barring any air resistance (e.g. assuming a vacuum) you can model this by thinking about in terms of it being in a falling elevator. This is the common thought experiment used to explain the universality of free fall (UFF) within the context of the Equivalence Principle [LINK] which is still a topic of exploration [LINK] . Essentially, without any other force acting, you will not see a rotation. However, as objects under uniform acceleration approach the speed of light the will encounter certain optical effects [this video] (note: this is a link to a youtube video explaining what
Cites BPilot · 2025-05 · Physics Stack Exchange · on “Is aberration of light counteracted by length contraction at relativistic speeds?”
When travelling at a significant fraction of the speed of light, the view ahead is squeezed in front of you and appears further away, while behind you it is stretched and enlarged. This is due to the aberration of light [LINK] . However, another relativistic effect is that everything is Lorentz contracted in the direction of travel, making the distance you're travelling appear shorter. So looking ahead, aberration is making things appear further away and at the same time Lorentz contraction is squeezing it shorter. Are these visually opposite effects counteracting each other? For context, what prompted this question is that there are quite a few interesting animations online, such as this vi