Expansion of the Universe, the Hubble relation and its limits
How it works
The expansion of the Universe describes that galaxies are, on average, moving away from one another on large scales. The Hubble relation (v = H₀·d) links the recessional velocity v of a distant galaxy or a distant galaxy cluster with the distance d. H₀ is the Hubble constant, whose value is determined experimentally. The relation is approximately valid on average on large scales. Within bound systems such as solar systems, galaxies, or within a galaxy cluster, the motion does not simply follow the Hubble relation, because gravity and peculiar motions are important there. Expansion does not mean that we are at the center, but that space itself is expanding. At very large distances or at very early times, the simple linear Hubble relation reaches its limits, since the expansion rate of the Universe has changed over the course of time.
The Hubble relation describes approximately the linear relationship between the distance d and the recessional velocity v on large scales: v = H₀·d. For motions within bound systems, this simple relation does not apply.
An example
Which statement correctly describes what is meant by the expansion of the Universe?
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50 Exercises · three difficulty levels · selection and number input
To the learning unit →Own explanation and own practice exercises by AmyMath. Subject reference framework: KMK Educational Standards Mathematics ESA/MSA. The topic assignment may vary by federal state.