Eli5: How can light not experience the passage of time if it travels at 670 million MPH – a measurement of time (and space)

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If light travels at 670 million miles per hour, then that means in one hour it will travel 670 million miles. At 2 hours it will travel 1214 million miles etc. This to me sounds like a measurement of time, just on such a huge scale that we can’t comprehend it. But in the grand scheme of the cosmos this is not that crazy of a scale. I would think it’s just saying light doesn’t experience time *relative* to us. But Einstein says no- no matter what, light’s speed doesn’t change and, what, relativity just doesn’t matter? It feels like a paradox

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18 Answers

Anonymous 0 Comments

Transversal electrical magnetism (Light) is a coaxial circuit that transverses electrical magnetic energy around a transverse longitudinal pulse perturbation.

Light doesn’t have a “speed”, it has a rate of induction, just like Magnetism. Magnetism causes us to experience “time” through it’s rate of induction. Force & Motion = time

When the rate of induction is equal to your velocity, “time” equalizes to zero, it’s effect is null. Like running as fast as a bullet to not be shot.

Anonymous 0 Comments

Space and time are the same thing. To say something experiences “time” is just saying that it’s moving in the physical direction (space) tangentially to our three dimensions of space. Since light is considered “infinitely fast”, it simply does not have a moment of its existence that is capable of moving in the direction of “time”, it is only “moving” relative to “space” – seemingly “instantly”.

Spacetime is oft misunderstood. People hear that space and time are the same thing but for some reason vehemently refuse to accept that they are indeed, literally, the same thing – our conscious awareness merely exists three dimensionally, so any spatial direction perpendicular to our three dimensions is experienced as “time”.

This video does an absolutely amazing job at describing this in an easy to conceptualize manner that builds upon itself, reducing the requirement for you to integrate all these separate thoughts yourself with intuition.

[Hyperbolic rotations of spacetime](https://youtu.be/qdycfWfAtsM)

Anonymous 0 Comments

Your calculation for 2 hours makes me laugh and I see what mistake was made. It would be 1340 not 1214.

Anonymous 0 Comments

The speed of light (causality) is the same for all reference frames. Regardless of how fast or slow we’re traveling compared to other things with mass, we all experience light moving at the same speed.

‘Length conraction’ and ‘ time dilation’ are observations from a frame of reference that can be stationary. At the speed of light in a vacuum the space shortens to zero and time stops. Not because the distance and time are zero, but because as a result of the ‘zero’ there is no valid reference frames.

Time is a side effect of moving slower than the speed of light. In 4D spacetime, everything moves at the same rate. Only so much of that can translate into motion in 3D space + time when mass is added.

Anonymous 0 Comments

Here is something I wonder about time and relativistic speeds-If I were to travel say at 99.% the speed of light in a giant loop for say 5 years in my ship and come back to Earth I understand It would be about 36 years later for my fellow earthlings and I would have aged just 5. If I brought a computer with me and used it to solve an extremely difficult math problem, say mining a bitcoin, would it represent 36 years worth of “work” on the computer problem or just 5?

Anonymous 0 Comments

The speed of light is not about light. Light just happened to be something that we discovered traveled at this speed so we called it the speed of light. Light can actually move slower than the ‘speed of light.’ This is why this term can be confusing. The real way to look at this, it is the speed of causality. The speed at which information can propagate and information can only travel at 3.0*10^8 meters/s. Sun disappears, it will take 8 minutes for gravity and illumination to change on Earth. So we will keep revolving around the non-existent Sun and see non-existent light because that information hasn’t reach Earth yet.

The speed of causality works on the Pythagorean theorem. A^2+B^2=C^2. Our location in space is a dimension, our location in time is a dimension. If you are perfectly still, you are then moving through time as max velocity, but as soon as you begin to move, your passage through time changes. Back to Pythag. A, your velocity in space, B your velocity in time, and A^2+B^2=C^2 where C is the speed of light/causality. The faster you move through space, the slow you move through time, so if you happen to be moving at 99% the speed of light/causality, any information you are giving to others is flying away from them rapidly and as a result, the information is stretched out so they see you moving through time slower. Like a doppler effect, but for cause and effect.

This is why many scientists say FTL travel is impossible. It would require time to move backwards. That you experience an effect you caused, before you caused it, i.e. A^2+B^2=C^2 but A > C, then B^2 needs to be a negative number, so now B must be an imaginary number so its square becomes negative and this is why the whole FTL concept breaks down.

Anonymous 0 Comments

In one hour it will travel 670 million miles *from your perspective*. Time is relative. For you, it takes an hour for the photon to travel 670 million miles, but from the photon’s perspective it’s instant. And this is because the faster something travels, the more spacetime contracts.

Anonymous 0 Comments

You’re movement through space and time are related, think of them as two numbers that add up to 1, change one number and the other will always change to balance the equation. I’m a way you’re always moving at the speed of light, but you’re experience of time is nearly 1 and your speed is low.

So if you’re not moving at all your speed is 0 and your perception of time is 1, you experience time as drawn out as possible. If you accelerate to half the speed of light your experience of time drops and the journey seems to take half as long as others would perceive it.

Take that to its final extreme and traveling at the speed of light the experience of time drops to zero so from your perspective your journey will be instant even though though years could have passed traveling.

As for why this happens, no idea, if you figure that out go collect your Nobel prize.