 A dimension is something that we use to help explain where a point in space is  For example, the point below is at (2, 3)  The elevator is at the lower level (LL)

 If something exists in 1 dimension, we can describe where it is using only a line  There is no height or width in 1 dimension, only length  Number lines are 1 dimensional  Example – The point is at -2

 We describe our houses locations in 1 dimension much of the time.  For example, Mr. Sandor’s favorite restaurant is located at rd Ave N Shapes are not possible in 1 dimension. There can only be 1 one line.

 If something exists in 2 dimensions, we need to use 2 lines to describe where it is.  A graph would be 2 dimensional. We need 2 lines to describe where a point is.  In 2 dimensions, there is length and height but no width.

 We can describe where the school is located using 2 dimensions  WMCI is located at the corner of Preston Avenue S and Taylor Street

 A 2 dimensional person would have no idea of “over” or “under”  They also could not have a 1 way digestive system because it would cut them in half

 If you need to use 3 lines to describe something, it is 3 dimensional  If something is 3 dimensional, it has length, width, and height.

 We are 3 dimensions. We have length, width, and height.  We can describe where someone is using 3 dimensions  Example Homer is on the corner of Preston Ave and Taylor on the 3 rd floor.

 The 3 dimensions we can move in are what make up space  This is not space as in outer space.  This is space as in the amount of space we take up  If you move through space, what you are really saying is that you are moving through 3 dimensions

 The 4 th Dimension that exists is time  When we need to describe the position of an object using length, width, and height as well as describe where it is and where it used to be, this is 4 dimensions

 Mickey is on the Ferris wheel in London. He is riding for 10 minutes.  He starts at the bottom of the wheel

 After 5 minutes, Mickey is at the top of the wheel  Not only did Mickey move through space, he also moved through time.

 We are 3 dimensional  We live in (at least) 4 dimensions  This means that we can control where we move in space (3 dimensions) but we cannot control how we move through time  We can witness ourselves move through time in ‘moments’

 Imagine a 2 dimensional person  That person has no idea what ‘above’ or ‘below’ are.  Imagine a 2 dimensional person seeing a 3 dimensional object (like a balloon)  They would only see ‘sections’ of the balloon.  To a 2 dimensional person, a balloon would first look like a dot, then a circle that grows larger, then a dot again.

 We are much the same as the 2 dimensional person  We are 3 dimensional but see only moments in the 4 th dimension  If we could see ALL of the 4 th dimension, we would see long ‘snakes’ that trail ahead and behind of everyone.

 Space and time are both connected  You cannot move through space without moving through time  You also cannot move through time without moving through space  People often refer to space and time as one thing called Spacetime Continuum (or spacetime)  Everything in our Universe is moving through the Spacetime Continuum

 As well as spacetime, our Universe also consists of 4 fundamental forces  Strong Force  Weak Force  Electromagnetic Force  Gravitational Force (or Gravity)

 Strong Force  This force holds protons and neutrons together in the nucleus of atoms  It is the strongest force  It has the shortest range Weak Force – This force causes radioactive decay (causes the nucleus to be unstable at certain times) – It is the not as strong as the strong force – It has a very short range Electromagnetic Force – This is the force that causes magnets and electricity to attract and repel objects – Only works on objects that have a charge – Has an infinite range Gravitational Force – This causes any objects with mass to be attracted to each other – Effects all objects with mass – Has an infinite range – Is the weakest force

 Everything is space is very far apart  only affected by forces with an infinite range  Not everything in space has a charge but everything has mass  Not everything affected by electromagnetic force  Everything affected by gravity  Because of these 2 reasons, gravity is the dominant force in the Universe  Everything in the Universe was made and shaped by gravity

 Gravity causes anything with mass to attract any other object with mass  The Moon is attracted to the Earth by the Earth’s Gravitational pull  The Earth is also attracted to the Moon  As the Earth pulls you down, you pull the Earth up  Gravity means that everything in the Universe is attracted to you, and you are attracted to everything in the Universe!

 Gravity depends on how much mass an object has  The greater the mass, the greater the gravitational pull

 Mass causes gravity by distorting (bending or reshaping) spacetime  Imagine spacetime like a giant sheet of fabric  If you add mass on the fabric, the sheet will droop  If you add greater mass onto the fabric, it will dip even further down creating a ‘well’

 Spacetime is actually curved and reshaped by all of the mass around it  This curved nature creates gravity  This means that even though it looks like a straight line from here to a star, it may actually be a curved path

 The Earth has enough velocity (speed) to keep going without ‘falling’ into the Sun  This is also why the Moon doesn’t run into the Earth

 One example of extreme gravity is a black hole  A black hole is something that has so much mass packed so tightly that it pulls everything close to it strongly to the point that even light cannot escape its gravitational pull

 Light is both a particle and a wave  We call the particles photons  To understand space, we need to understand light  Light is how we observe space. We look at the light given off by stars and galaxies. We examine the colours of light that reflect of planets, moons, and nebula. This is how we learn about space is through light

 Light acts as a wave.  Every wave has some properties that we need to know  Wavelength  Amplitude

 Waves go up and down over time.  Waves transmit energy  Amplitude is how high or low a wave goes  Amplitude is what determines how powerful a wave is  It is often referred to as peaks (ups) and troughs (downs)

 The wavelength of a wave is how long it takes for a wave to complete a cycle  The length from peak to peak or trough to trough  The shorter the wavelength, the greater the energy  The longer the wavelength, the less energy

 The amplitude of a light wave determines brightness  A 100W light bulb gives out light with greater amplitude than a 40W light bulb  The wavelength of a light wave determines the energy and the colour  The shorter the wavelength, the higher the energy  The longer the wavelength, the less the energy

 The colour of the light is determined by how long a wave is.  Shorter waves look blue  Longer waves look red

 There is more light than what our eyes can see  We see a tiny portion of all the light that exists. We only see visible light  Other forms of light include X-rays, gamma rays, radio waves, microwaves, infrared, ultraviolet

 Each element gives off its own colours  Each element emits and absorbs specific colours of light  This is why copper burns green and strontium burns red  We can determine what stars, planets, nebula, etc. are made of by the colours of light they emit

 Waves must travel through a medium  Ocean waves transmit energy through water  Sound waves transmit energy through air  Light waves transmit energy through space  Light travels through space so it is affected by gravity’s bending of space

 Nothing can travel faster than the speed of light  The speed of light is like a cosmic “speed limit”  If things get fast enough to approach the speed of light, other values such as time, length, and mass of an object will change  Light moves at 300 million metres per second

 Light takes time to travel from one place to another  It takes 8 minutes for light to reach Earth from the Sun  To measure distant objects we use the measurement light- years  Light years are the amount of distance light travels in 1 year – about 9.5 trillion kilometres

 The nearest star to Earth other than the Sun is Proxima Centauri  4.24 light years from Earth  When we see Proxima Centauri, we are actually seeing what it looked like 4.24 years ago  That is the amount of time it takes light to get here from that star

 The furthest object from Earth ever seen was billion light-years  This means it took billion years for the light to travel to Earth for us to see it.  This object was a protogalaxy – a cloud of gas that began to form one of the first galaxies