P1 topic 3&4

Question 1

What does the steady state theory entail?

Answer 1

the universe is expanding; has unchanging density; spontaneously created matter (especially hydrogen) from empty space to maintain the same density; has no beginning and will never end

Question 2

who proposed the Big Bang theory?

Answer 2

a group of scientists including George Gamov in 1948

Question 3

What does the Big Bang theory entail?

Answer 3

the universe is expanding; is finite and ever changing; was created about 14 million years ago from an event called the Big Bang; may have an end, depending on its density

Question 4

why do most scientists today believe in the Big Bang theory?

Answer 4

it explains the red shift of light from distant galaxies and the existence of cosmic microwave background radiation

Question 5

cosmic microwave background radiation

Answer 5

the left over radiation from the Big Bang- radiation coming very faintly from all directions in space

Question 6

What can CMB be detected with?

Answer 6

a radio telescope- it’s the same strength in all directions

Question 7

What is the evidence that the universe is expanding?

Answer 7

The light from all distant galaxies is red shifted- this means that all galaxies are moving away from us and each other- the further away the galaxy, the greater the red shift. This means that the more distant galaxies are moving away more quickly

Question 8

What happened at the moment of the Big Bang?

Answer 8

all matter expanded from a hot, dense singularity; after the first few seconds, hydrogen and helium were produced; as the universe expanded, it cooled; stars and galaxies formed

Question 9

Why is the Steady State theory rejected?

Answer 9

although it can explain the red shift of distant galaxies, it can’t explain the presence of CMB radiation or the abundance of light elements such as helium in the atmosphere

Question 10

What is the evidence for the Big Bang theory?

Answer 10

red shift is prove of expansion; temp of universe was predicted to be -270, confirmed by the COBE satellite in the ’90s; original radiation created in Big Bang would have been gamma, Doppler effect stretched wavelength to become microwave (wavelength of about 1mm)

Question 11

When was the steady state theory proposed?

Answer 11

it was proposed by a group of scientists including Fred Hoyle in 1946

Question 12

What animal uses ultrasound for communication?

Answer 12

dolphins

Question 13

what animal uses infrasound for communication?

Answer 13

whales

Question 14

How does foetal scanning work?

Answer 14

different body tissues reflect ultrasound by differing amounts and the echoes are used to create an image

Question 15

how is infrasound produced naturally?

Answer 15

by volcanoes, avalanches, ocean waves, hurricanes, earthquakes, meteorite explosions and animal movements

Question 16

how is infrasound produced by human activity?

Answer 16

drilling for oil and nuclear or chemical explosions

Question 17

how do humans use infrasound?

Answer 17

to detect and monitor animal movements in remote locations and volcanic activity/meteorite strikes

Question 18

inner core

Answer 18

very hot and dense solid iron

Question 19

outer core

Answer 19

very hot, dense and liquid, mostly iron

Question 20

mantle

Answer 20

hot, less dense and a mixture if solid and molten rock

Question 21

crust

Answer 21

a very thin layer of solid rock

Question 22

what does the crust float on?

Answer 22

a hot liquid called magma

Question 23

why do the tectonic plates move very slowly?

Answer 23

due to the convection currents in the magma

Question 24

who first suggested the movement of the earth’s crust?

Answer 24

Alfred Wegener in 1915

Question 25

What evidence supports Wegener’s ideas?

Answer 25

ancient rocks found in East Africa were identical to those found in South America; fossils found in both regions were the same species of ancient aquatic reptile

Question 26

Why are earthquakes and tsunamis so unpredictable?

Answer 26

scientists can’t measure the pressure between the tectonic plates; the fault lines are often deep within the Earth’s crust

Question 27

spectrometer

Answer 27

a device used for looking at the spectrum of light

Question 28

what do modern telescopes have built in?

Answer 28

sophisticated spectrometers

Question 29

how can scientists identify the chemical composition of stars?

Answer 29

by examining the light they emit with a spectrometer

Question 30

What EM waves are not absorbed at all by the atmosphere?

Answer 30

radio waves- this is why they are used for communications

Question 31

which EM waves are almost all

absorbed by the atmosphere?

Answer 31

gamma and x-rays

Question 32

Doppler effect

Answer 32

the change in wavelength/frequency of a wave as a result of relative motion between the source and an observer

Question 33

blue shift

Answer 33

the wavelength of light decreases (and frequency increases) as a light source moves towards an observer

Question 34

red shift

Answer 34

the wavelength of light increases (and frequency decreases) as a light source moves away from an observer

Question 35

what happens the faster the source is moving?

Answer 35

the greater the Doppler shift will be