LAB SAFETY AND HISTORY OF THE UNIVERSE

Section A: Lab Safety

Before you read this unit, complete the following mind-map activity on lab safety. Use your prior knowledge of lab safety and describe it on the mind map.

(Attachment 1: Lab Safety Mind Map)

When conducting laboratory experiments, lab safety should always be your main priority. Follow these guidelines to ensure the safety of yourself and others around you whenever you do an experiment.

Clothing and Personal Grooming

Wear well-fitting clothing. Avoid wearing loose or baggy items, as these could get in the way. Wear goggles, gloves, apron, and/or lab coat as specified in each experiment. If you have long hair, pull it back and secure it.

Procedures

Read and follow the procedures for every laboratory experiment. It is important to read the entire experimental procedure before starting any work on the experiment. If you are not sure what something means, ask for help or further directions before proceeding with the experiment.

Laboratory Equipment

Learn how to use each piece of equipment safely and properly; do not play with the equipment. Never touch or taste experiment ingredients unless told to do so.

Cleanliness

Upon completing the experiment, clean up your equipment and work space. Make sure to wash your hands after every experiment.

Behavior

Demonstrate responsible behavior at all times. It is crucial to be aware of your own safety and the safety of those around you. Avoid running and horseplay in the lab setting.

Now, complete the following activity on lab safety.

(Attachment 2: Lab Safety Posters Activity)

Please answer questions 1 through 6 in the question section below before moving on to Section B.

Section B: History of the Universe

Formation of the Universe

A science topic that has been debated for centuries is the formation of the universe. Several theories have been proposed, shared, studied, and debated over time. One generally accepted theory is known as the Big Bang theory. This theory proposes that the universe began with a big bang (explosion or expansion) and has been expanding ever since. The origin of the big bang is one of the greatest mysteries of all time. Theoretical physicists and cosmologists reveal how our understanding of the universe has changed during the twentieth century and ponder how something as complex as our universe could come from nothing.

Was the Big Bang an Explosion

Evidence for the Big Bang Theory

According to the Big Bang theory, the universe expanded quickly and then cooled enough for atoms to form. Gravity pulled the atoms toward one another to form gas clouds that eventually gave birth to stars. This is how galaxies began to develop over long periods of time. As time goes on, the galaxies continue to move away from one another at great speeds, and as thus, the universe continually expands.

There are several types of evidence which support the Big Bang theory:

- Hubble’s Law

- redshifts

- cosmic microwave background radiation.

Hubble’s Law explains that galaxies which are further away from Earth are moving at proportionally greater velocities. The further a galaxy’s distance from Earth, the greater its redshift. Hubble theorized that the universe’s dominant motion has a smooth expansion factor, which is now called the Hubble constant. He originally believed it to be about 500 km/sec/Mpc (kilometers per second per megaparsec). The value today remains uncertain, but is believed to be closer to a range of 45-90 km/sec/Mpc. Note: a parsec is used to measure the large distances from our galaxy to neighboring galaxies and clusters. A megaparsec is one million parsecs.

This chart shows possible scenarios for universal expansion, with the red curve supporting Hubble’s Law: http://wmap.gsfc.nasa.gov/universe/bb_concepts_exp.html

Redshift is based on an understanding of the Doppler Effect. The Doppler Effect is the apparent difference between the frequency at which sound or light waves leave a source and that at which they reach an observer, caused by relative motion of the observer and the wave source. For example, a fire truck is moving toward you. As it approaches, the pitch of the siren appears to get higher, and as it drives away, the pitch seems to be somewhat lower. If you are to apply the principle to moving light, an object that is rapidly moving closer will have more of a blue appearance, while an object moving away will emit a red light. This is known as redshifting. As celestial objects and galaxies move away from the Earth, they displace red light on the spectrum. A longer redshift shows a greater speed of recession from Earth.

Follow the links below for more information on the Doppler Effect and Redshift.

Doppler Effect, explained: http://www.exploratorium.edu/origins/hubble/tools/doppler.html

Doppler Effect, examples: http://www.pbs.org/wgbh/nova/universe/moving_nf_01.html

***Click through and read all four pages associated with the above link.***

Britannica Video
The username and password for Britannica is as follows: (username: vla) (password: student)

Redshift, explained: http://school.eb.com/levels/high/article/62957

Khan Academy Video

Redshift, example: https://www.khanacademy.org/science/cosmology-and-astronomy/universe-scale-topic/big-bang-expansion-topic/v/red-shift

Cosmic microwave background radiation (or CMB radiation) is a remnant glow of radiation from the Big Bang. It is often referred to as “leftover light.” About 380,000 years after the Big Bang, the universe became transparent as ionized hydrogen and helium bonded with electrons to form neutral atoms. This allowed light to travel freely. Closer to when the CMB radiation was initially released, it was emitted as visible and ultraviolet light. But as the universe has expanded and redshifted over billions of years, the wavelengths became longer until the present, when it appears in the form of microwave radiation. It was Arno Penzias and Robert Wilson who discovered CMB radiation when using their microwave radio telescope in 1964. The radiation energy is uniform across all areas of the observable universe, and the temperature is about -270 degrees Celsius, or only 2.7 degrees above absolute zero.

Map of CMB radiation

WATCH THIS Video: “The cosmic microwave background: A new view from the South Pole”

https://www.khanacademy.org/partner-content/amnh/the-universe/universe/v/cmb-new-view-south-pole

Unit Vocabulary Review

Click on the Quizlet icon below to access the quizlet.com vocabulary flash cards. Review the vocabulary before completing your assessment.

Extension: Related article

http://www.astronomy.com/news/2014/11/gravity-may-have-saved-the-universe-after-the-big-bang

After completing all unit activities, answer questions 7-15 in the question section below.