We All Travel Through Spacetime at the Speed of Light
Our speed through spacetime is constant. The more we move through space, the less through time and vice versa.
Everything travels through spacetime at the speed of light. Me, you, the cat (even Schrödinger's cat), the Earth, the sun, bits and bytes, and any particles including photons (light particles).
Note that I said spacetime. Of course, we travel at different speeds through space, we might even be standing still in our frame of reference. This frame of reference is moving relatively in other frames of reference, for example you might be sitting still while reading this, but you are on Earth (I’m guessing), which is spinning at 1,600 km/h at the equator, and Earth is also moving around the Sun (107,000 km/h), and the Sun is moving around the center of the Milky Way (828,000 km/h). Milky Way is also moving in relation to any other galaxy at 600 km/s or 2,160,000 km/h.
But none of the above mentioned, except for photons, travel at the speed of light through space (which is 300,000 km/s or 1,080,000,000 km/h for comparison). Our motion through spacetime, on the other hand, is different.
We all travel at exactly the speed of light through spacetime.
