Have you ever wondered how fast the Earth is moving?
Did you know that the “net speed of the Earth through the universe” is approximately 368 to 370 kilometres per second (about 1.3 million kilometres per hour). Because velocity is entirely relative – meaning a specific reference point to measure against must be chosen – this net speed is calculated relative to the Cosmic Microwave Background (CMB). The CMB is the leftover radiation from the Big Bang that fills all of space, acting as the closest thing the universe has to an “absolute” cosmic backdrop.
When satellites like NASA’s WMAP or Europe’s Planck space observatory look at the cosmos, they observe what is termed a dipole anisotropy in the CMB: because of the Earth’s net movement, the light ahead of the Earth is slightly blue-shifted (compressed and warmer), while the light behind is red-shifted (stretched and cooler). By measuring this shift, the exact speed and direction through the cosmic rest frame can be calculated.
Nested Gears
The net speed is not a simple sum of all cosmic movements because these motions point in completely different directions and change over time. They act like nested gears:
Lower Net speed
The Net Speed is Lower Than the Galaxy’s Speed because the Sun’s orbit around the centre of the galaxy currently points in a mostly opposite direction to the path the galaxy is traveling through the universe. As a result, the orbital speed around the galaxy partially cancels out the galaxy’s speed through the cosmos. Furthermore, because the Earth changes its direction around the Sun every six months, the net speed fluctuates slightly by about 30 km/s throughout the year.
No such thing as “absolute space”
In these calculations, it is important to remember that there is no such thing as absolute rest or absolute space. While the CMB feels like a “universal frame of rest,” Einstein’s theory of relativity dictates that it is just a convenient frame of reference, not a ‘legally preferred’ one by the laws of nature. The CMB is simply the radiation left over from the early universe. Because it fills all of space evenly, it can be used like a giant grid to measure Earth’s speed against. Moving through it gives a relative speed to the radiation, but it does not mean that the Earth is moving through “absolute space”, as, according to Einstein’s Theory of Relativity, there is no such thing as “absolute space”: space is not a physical grid or a rigid stage; rather, it is defined entirely by the relationships between things.
Space and time not the basic building blocks of the universe, but something created by deeper things
Further, it seems that space, or rather spacetime, the unified four-dimensional fabric of the universe, is not, itself, fundamental, but rather an emergent property, a visual manifestation of some underlying form of quantum connectivity: it is possible, with quantum information and entanglement, that the four-dimensional fabric of the universe is woven together by quantum entanglement, acting as the underlying connectivity that generates spatial distance and the temporal flow of events, positioning spacetime as a geometric map of evolving information; alternatively, with loop quantum gravity, it may be that the four-dimensional fabric of the universe is woven from a microscopic network of quantized geometric bits, with intersections in this network creating discrete packets of volume, while the links between them create areas of space, all changing from one state to the next in discrete ticks, manifesting as time.
