Experiencing Science Notes

Experiencing Science Notes – Semester One 2019

Scientific questioning: Raising questions that can be investigated using scientific method (research in which a problem is identified, relevant data gathered, a hypothesis formulated from the data, and the hypotheses empirically tested).

Fair testing: Part of the scientific method involves fair testing. When a test is fair, only one thing is changed (the independent variable). The scientist decides exactly what to measure (the dependent variable). Everything else is kept the same (the control variables). This way any change observed in the outcome (i.e. the dependent variable that is measured) can be attributed to a change in the independent variable. A helpful acronym to remember this is Cows Moo Softly – Change only one thing; Measure something; Keep everything else the same.

Data integrity: Maintaining and assuring the accuracy and consistency of data over its entire life-cycle.

The Big Bang

• Edward Hubble – The universe is expanding
• Hubble then thought if he could figure out the speed at which the universe is expanding, he could also figure out when the universe was formed.
• Redshift is the lengthening of wavelengths of light. Where visible light and increasing wavelength corresponds to a shift toward the red end of the spectrum.
• Blueshift means that the wavelength of light becomes shorter.
• Astronomers like Vesto Slipher and Edwin Hubble discovered this using spectroscopic instruments to observe spectral lines shifting away from where they would normally be, indicating redshift or blueshift.
• The Doppler effect can be described as the        effect        produced by        a moving source of waves in        which        there        is an apparent upward shift in frequency for observers towards whom the source is approaching and an apparent downward shift in frequency for observers from whom the source is receding.
• Astronomers use information about the shift in frequency of electromagnetic waves produced by moving stars in our galaxy and beyond in order to derive information about those stars and galaxies.
• The idea that the universe is expanding is based in part upon observations of electromagnetic waves emitted by stars in distant galaxies.
• 13.7 Billion Years ago.
• Everything in the universe was squashed into a tiny space (smaller than an atom).
• After Big Bang – Universe at 10 Billion degrees.
• As the universe starts to cool, four fundamental forces appear:

• Gravity
• Electromagnetism
• Strong Nuclear Force
• Weak Nuclear Force

• These strong and week nuclear forces bind the centre of the nuclei in atoms.
• ENERGY – Matter or radiation that’s is capable of exerting force or doing work
• MATTER – Physical substance, a form of congealed energy.
• The universe soon became a plasma universe as electrons and protons could not yet combine.
• PLASMA UNIVERSE – a common state of matter similar to gas but more responsive to electromagnetic forces. Dominated by charged particles.
• These charged particles cling to photons of light = light cannot move freely through the universe.
• Atoms also cannot be formed as of yet.
• Fred Hoyle – A sceptic of the theory described Hubble’s theory jokingly as the Big Bang and it stuck.
• Atomic Weapons – Helped create an idea about what matter and energy would be doing during the big bang as these weapons were all about extreme conditions.
• Einstein – Under extreme heat, Matter and energy are interchangeable.
• (Energy = Mass x Speed of light (2))
• As universe expanded it would have cooled.
• 380000 yrs. after the Big Bang, Temperature of universe = 3000 degrees
• 380000 Years after big bang = Plasma ends = can now form atoms.
• Instead of plasma, the universe is now full of electrically neutral atoms. This means photons of light can move freely.
• First Atoms formed = H, He
• 1960s – Arno Penzias and Robert Wilson were trying to build a sensitive radio receiver when suddenly stumbling across the flash of energy.
• This discovery is now known as The Cosmic Microwave Background (CMB).
• The CMB is the oldest light in the universe.
• The photons in the CMB were “released” to travel freely through the Universe at the time when atoms first formed. Before that time, they were “locked up” in the plasma of the early Universe.
• This discovery was extremely powerful evidence for big bang cosmetology as it supported a strange prediction made in the 1940s.
• The Big Bang is important as it created time, space and the building blocks of our universe.

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