Technically everything moves at c (the speed of light) through spacetime, all the time. Most objects that have mass spend the majority of their motion in the time part, and thus move relatively slowly in space. If an object moves fast in space (where fast is a significant fraction of c) then it moves noticeably slower in time because the total spacetime vector value is always c.
Photons, being massless, do not move through time at all, and move through space at c.
That’ll break a few brains. To elaborate with an example: From the perspective of a photon, it’s “life” is over as soon as it begins. Even though it takes about 8 mins for a photon to travel from the sun to the earth from our perspective, no time at all has passed for it.
Light is generally better modeled by a wave, so I would say the wave doesn’t experience time. Photons are the smallest unit of energy that can be transferred between a light wave and a different particle. They have momentum and direction, but they don’t really travel exactly. They just mediate the force between light waves and matter.
Worded differently, a fermion (massive particle) within an electromagnetic (light) wave with a frequency of f may absorb some multiple of h x f joules of energy, where h is a very small constant. There is no way for the wave to transfer less than hf joules to the particle at a time. There is no need to think of photons as anything other than the smallest possible quantization of the electromagnetic wave rather than a particle of light. There’s no need to think of it existing for any amount of time or space.
Photons are the smallest unit of energy that can be transferred between a light wave and a different particle.
That is a much better description than what I have heard for the last 30 years: “A photon is a packet of energy”. That made no sense to me back then, and makes no sense to me now and, IMHO, doesn’t quite give a good visualization. It’s a placeholder, and I suppose it is slightly accurate depending on how “packet” is defined.
That’s awesome, and I totally agree. Everyone already intuitively knows that waves carry energy. We’ve all heard of tsunamis and earthquakes. The only difference on the quantum scale is that the amount of energy transferred is discretized.
I’m reasonably sure that Einstein’s breakthrough was more that he assumed light only travels at the speed of light and the all the equations worked.
Every experiment since has confirmed it.
Technically everything moves at c (the speed of light) through spacetime, all the time. Most objects that have mass spend the majority of their motion in the time part, and thus move relatively slowly in space. If an object moves fast in space (where fast is a significant fraction of c) then it moves noticeably slower in time because the total spacetime vector value is always c.
Photons, being massless, do not move through time at all, and move through space at c.
That’ll break a few brains. To elaborate with an example: From the perspective of a photon, it’s “life” is over as soon as it begins. Even though it takes about 8 mins for a photon to travel from the sun to the earth from our perspective, no time at all has passed for it.
(Correct me if I misspoke.)
Light is generally better modeled by a wave, so I would say the wave doesn’t experience time. Photons are the smallest unit of energy that can be transferred between a light wave and a different particle. They have momentum and direction, but they don’t really travel exactly. They just mediate the force between light waves and matter.
Worded differently, a fermion (massive particle) within an electromagnetic (light) wave with a frequency of f may absorb some multiple of h x f joules of energy, where h is a very small constant. There is no way for the wave to transfer less than hf joules to the particle at a time. There is no need to think of photons as anything other than the smallest possible quantization of the electromagnetic wave rather than a particle of light. There’s no need to think of it existing for any amount of time or space.
That is a much better description than what I have heard for the last 30 years: “A photon is a packet of energy”. That made no sense to me back then, and makes no sense to me now and, IMHO, doesn’t quite give a good visualization. It’s a placeholder, and I suppose it is slightly accurate depending on how “packet” is defined.
That’s awesome, and I totally agree. Everyone already intuitively knows that waves carry energy. We’ve all heard of tsunamis and earthquakes. The only difference on the quantum scale is that the amount of energy transferred is discretized.
To add to this, this is always relative to an observer. If an object moves fast in space compared to you then it moves slower in time compared to you.
Any speed that light travels is the speed of light
The real breakthrough
The other way around. Experiments said that light always moves at C and he deduced what follows from that for space time.