9702 · 25.3
Hubble's law and the Big Bang theory
Prepare to unravel one of the most profound ideas in physics: the **expansion of the universe** and its origins in the **Big Bang Theory**. This lesson will guide you through the key evidence, particularly **galactic redshift**, and introduce you to **Hubble's Law**, which quantifies this cosmic expansion. We'll also explore how astronomers measure the immense distances involved using **standard candles** and examine the crucial evidence provided by the **Cosmic Microwave Background**.
Need to know
What you need to know
- Astronomers investigate objects in space by looking at their emission and absorption spectra.
- Elements in a star's atmosphere absorb specific wavelengths, creating dark lines in its spectrum.
- When comparing the spectra of distant galaxies to those of nearby stars (like our Sun), these spectral lines are found to be shifted.
- For almost all distant galaxies, the lines show an increase in wavelength, a shift towards red.
Explanation
Hubble's law and the Big Bang theory
- Astronomers investigate objects in space by looking at their emission and absorption spectra.
- Elements in a star's atmosphere absorb specific wavelengths, creating dark lines in its spectrum.
- When comparing the spectra of distant galaxies to those of nearby stars (like our Sun), these spectral lines are found to be shifted.
- For almost all distant galaxies, the lines show an increase in wavelength, a shift towards red.