By Akshath Sivaprasad

The Expanding Universe

• Discovered by Edwin Hubble in 1929

• Measured redshift (change in star’s spectrum,

caused by star moving away from earth) from

different galaxies

• Concluded that wavelengths became red (stars

were moving away), leaving one possible

definition: the universe was expanding

Background Info

• The Big Bang Theory answers the question: How did the universe begin?

• If the universe is expanding, then it must have in the past too. If we go back in time, the universe shrinks, and we eventually reach a period where the universe is a point.

• The point was infinitely dense, infinitely hot, and infinitely small. This point inflated, expanded, and cooled. is known as the Big Bang.

• From its original size, it expanded and cooled to the size of our current universe.

The Big Bang TheoryBackground

1. The universe must have had some beginning

2. Galaxies are moving away (Hubble’s Law as shown before)

3. Because the Big Bang was so hot, there must still be some remnant of heat. A radiation in 1965 was thought to be this remnant.

4. The hydrogen and helium elements are thought to be products of the Big Bang, which is why we those elements in abundance.

The Big Bang TheoryEvidence

this diagram shows how the universe started of as a point (bottom) and became the universe as we know it today, complete with several galaxies (top)

• the Big Bang Theory• universe was point current universe• shows universe was (and is) expanding

• evidence from Edwin Hubble:• measured redshift from each close galaxy• redshift is when the wavelengths from distant

galaxies lean towards the red spectrum, signifying that the galaxies were moving away

• the galaxies moving away caused the green and blue colors to fall out of the wavelength leaving red (the only durable color) to reach us

• found that galaxies were moving away• known as Hubble’s Law

Why the Universe is Expanding

Information

www.wikipedia.org/wiki

www.big-bang-theory.com

www.skyserver.sdss.org

www.universe today.com

Pictures

www.wikipedia.org/wiki

www.delamangente.files.wordpress.com

Sources