PEARSON PRENTICE HALL PHYSICAL SCIENCE CONCEPTS IN ACTION

PEARSON PRENTICE HALL PHYSICAL SCIENCE: CONCEPTS IN ACTION CHAPTER 26 EXPLORING THE UNIVERSE Chapter 26. 5 THE EXPANDING UNIVERSE

HUBBLE’S LAW AND RED SHIFTS • Def: The universe is the sum of all matter and energy that exists, that ever has existed, and that ever will exist • In 1929, Edwin Hubble announced that atoms in stars emit light toward the red end of the light spectrum • Hubble’s Law says that the speed at which a galaxy is moving away is proportional to its distance from us • This helped to formulate the evidence to support the Big Bang Theory

DOPPLER EFFECT • The Doppler effect is used to determine how fast stars are moving toward or away from Earth • Def: the Doppler effect is the change in wave frequency and wavelength as an object moves toward or away from you • Def: Red shift is a shift toward the red end of the spectrum in the observed spectral lines of stars or galaxies • When a object moves away from Earth, the light source moves away & wavelengths become longer toward the red end of the spectrum http: //www. astro. ucla. edu/~wright/doppler 2. gif http: //wps. pearsoned. com. au/wps/media/objects/8331/8531591/_images_/ch 8 b. jpg

THE DOPPLER EFFECT CLIPS https: //www. youtube. com/watch? v=h 4 On. BYrb. Cj. Y https: //i. makeagif. com/media/10 -08 -2015/ogr 3 b. Y. gif https: //www. youtube. com/watch? v=p-h. BCcm. CUPg

EXPANDING UNIVERSE • The red shift means that every galaxy is moving away from Earth & that the universe is expanding • Every galaxy is also moving away from each other implying that the universe is expanding and was once much smaller http: //www. astro. ucla. edu/~wright/balloons. gif

THE BIG BANG • The Big Bang was not an explosion in space, as theory's name might suggest. Instead, it was the appearance of space everywhere in the universe, researchers have said. • According to the Big Bang theory, the universe was born as a very hot, very dense, single point in space. https: //www. space. com/13320 -big-bang-universe-10 -steps-explainer. html https: //i. makeagif. com/media/8 -06 -2015/a 0_lyj. gif

BIG BANG AND COSMIC BACKGROUND RADIATION (CBR) • It is unclear what happened before this moment but a key part of this comes from observations of the cosmic microwave background, which contains the afterglow of light and radiation left over from the Big Bang. • This remnant of the Big Bang saturates the universe and is visible to microwave detectors, which allows scientists to piece together clues of the early universe.

COSMIC BACKGROUND RADIATION CONTINUED • When the universe was only a hundredth of a billionth of a trillionth of a second — it underwent an unbelievable expansion (inflation) • It grew exponentially and doubled in size at least 90 times, as it was expanding it became cooler and less dense • As it continued to grow it grew at a slower rate and matter was formed. https: //www. space. com/13320 -big-bang-universe-10 -steps-explainer. html

BIG BANG AND COSMIC BACKGROUND RADIATION (CBR) • Light chemical elements were created within the first three minutes of the universe's formation. • As the universe expanded, temperatures cooled and protons and neutrons collided to make an isotope of hydrogen which then combined to make helium. • Atoms crashed together with enough force to break up into a dense, cloudy plasma of protons, neutrons and electrons that scattered light like fog. • About 380, 000 years after the Big Bang, matter cooled enough for electrons to combine with nuclei to form neutral atoms ("recombination") and the absorption of free electrons caused the universe to become transparent. • The light that was released at this time is detectable today in the form of radiation from the cosmic microwave background. https: //www. space. com/13320 -big-bang-universe-10 -steps-explainer. html

COSMIC BACGROUND RADIATION • We will assume the universe is about 14 billion years old • In this theory there is no time, no space and nothing at all before the Big Bang • Def: Cosmic background radiation which is a steady, dim radiation detected at microwavelengths is believed to support this theory • Expansion is cooling the universe • The red shift also supports theory • Scientists believe that the universe is still expanding today https: //sos. noaa. gov/images/Solar_System/wmap. jpg

DARK MATTER • Whether or not the universe continues to expand depends on the amount of mass of the entire universe • It is not known for how long the universe will continue to expand • If there is not enough mass, gravity will be too weak to stop the expansion • If mass is just right, expansion will slow down but never stop

DARK MATTER PART 2 • If there is too much mass, gravity will take over and the universe will contract again, causing a “big crunch” & the whole thing could happen again • The amount of matter is determined by matter that can be seen such as stars, and matter that cannot be seen • Def: Dark matter is matter that cannot be seen directly, but its presence can be detected by observing its gravitational effects on visible matter • Dark matter is matter that does not give off radiation https: //img. purch. com/w/660/a. HR 0 c. Dov. L 3 d 3 dy 5 zc. GFj. ZS 5 jb 20 va. W 1 h. Z 2 Vz. L 2 kv. MDAw. Lz. Ax. NS 8 w. MDQvb 3 Jp. Z 2 lu. YWwvbm 9 yb. WFs. LWRhcmstb. WF 0 d. GVy. L WNvb. XBhcmlzb 24 uan. Bn

EXPANSION ENDS? • The universe contains a lot of dark matter • This amount of matter indicates that there is enough mass to keep the universe expanding • In the past, scientists have discovered that the rate of universe expansion may be increasing • Galaxies are moving apart faster than expected • Scientists have named the mysterious force causing this “dark energy” • If expansion is accelerating, it’s likely that the universe will expand forever

WHAT ARE THREE MAIN CONCEPTS THAT HELP SUPPORT THEORY OF BIG BANG 1. the red shift of light from galaxies as an indication that the universe is currently expanding, https: //i. makeagif. com/media/1008 -2015/ogr 3 b. Y. gif 2. the cosmic microwave background as the remnant radiation from the Big Bang, and https: //sos. noaa. gov/images/Solar_System/wma p. jpg 3. the observed composition of ordinary matter of the universe, primarily found in stars and interstellar gases (from the spectra of electromagnetic radiation from stars http: //abyss. uoregon. edu/~js/images/spectrum_binary. gif