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- https://phys.libretexts.org/Courses/University_of_California_Davis/Physics_156%3A_A_Cosmology_Workbook/01%3A_Workbook/1.04%3A_Spatially_Homogeneous_and_Isotropic_SpacetimesWe introduce the cosmological principle and the geometry of homogeneous and isotropic spacetimes with three spatial dimensions. This will allow us to go on to calculate distance-related observables, a...We introduce the cosmological principle and the geometry of homogeneous and isotropic spacetimes with three spatial dimensions. This will allow us to go on to calculate distance-related observables, an important step toward predicting observable consequences of the expansion.
- https://phys.libretexts.org/Courses/University_of_California_Davis/Physics_156%3A_A_Cosmology_Workbook/01%3A_Workbook/1.09%3A_A_Newtonian_Homogeneous_Expanding_UniverseRetreating to the use of Newtonian concepts, we show that for a universe to be filled with an expanding fluid that remains homogeneous over time, the flow must be what we call a Hubble flow, with rela...Retreating to the use of Newtonian concepts, we show that for a universe to be filled with an expanding fluid that remains homogeneous over time, the flow must be what we call a Hubble flow, with relative velocities proportional to distance. Thus we derive Hubble's law using Newtonian concepts, setting ourselves up for the next chapter in which we use Newtonian dynamics to relate the expansion rate to the contents of the cosmos.
- https://phys.libretexts.org/Courses/University_of_California_Davis/Physics_156%3A_A_Cosmology_Workbook/01%3A_Workbook/1.37%3A_RedshiftsWe begin to work out observational consequences of living in an expanding spatially homogeneous and isotropic universe. In this and the next two chapters we derive Hubble's Law, v=H0d, and a m...We begin to work out observational consequences of living in an expanding spatially homogeneous and isotropic universe. In this and the next two chapters we derive Hubble's Law, v=H0d, and a more general version of it valid for arbitrarily large distances.
- https://phys.libretexts.org/Bookshelves/University_Physics/University_Physics_(OpenStax)/University_Physics_III_-_Optics_and_Modern_Physics_(OpenStax)/11%3A_Particle_Physics_and_Cosmology/11.07%3A_The_Big_BangThe universe is expanding like a balloon—every point is receding from every other point. Distant galaxies move away from us at a velocity proportional to its distance. This rate is measured to be appr...The universe is expanding like a balloon—every point is receding from every other point. Distant galaxies move away from us at a velocity proportional to its distance. This rate is measured to be approximately 70 km/s/Mpc. Thus, the farther galaxies are from us, the greater their speeds. These “recessional velocities” can be measure using the Doppler shift of light. According to current cosmological models, the universe began with the Big Bang approximately 13.7 billion years ago.
- https://phys.libretexts.org/Courses/University_of_California_Davis/Physics_156%3A_A_Cosmology_Workbook/01%3A_Workbook/1.03%3A_RedshiftsWe begin to work out observational consequences of living in an expanding spatially homogeneous and isotropic universe. In this chapter we introduce the concept of redshift and work out the relationsh...We begin to work out observational consequences of living in an expanding spatially homogeneous and isotropic universe. In this chapter we introduce the concept of redshift and work out the relationship between it and the history of the expansion.
- https://phys.libretexts.org/Courses/University_of_California_Davis/Physics_156%3A_A_Cosmology_Workbook/01%3A_Workbook/1.06%3A_Distances_as_Determined_by_Standard_CandlesThe consequences of expansion are recorded in the relationship between distance and redshift. Here we introduce the so-called standard candle method of distance determination. We work out the theoreti...The consequences of expansion are recorded in the relationship between distance and redshift. Here we introduce the so-called standard candle method of distance determination. We work out the theoretical relationship between flux, luminosity, curvature constant k, coordinate distance between observer and source, and the redshift of the source. This moves us one step closer to being able to infer the expansion history from observations.
