Where Are All the Aliens?

Public summary: 

CBS Talk 2017/18

Where might aliens live, how can we look for them and why haven't we found any?
Useful information
Kit List: 

Diffraction Grating
Elastic bands
Tuning fork

(Polystyrene planets)
(Sun/moon/earth hats)
(Pulsar model?)
(Active Expression Handsets?)


1. Rubbing hands together for frictional heating
2. Cooling water in two different sized beakers to show that high surface area to volume ratio cools things quicker – volunteers to pick beaker and perform measurement
3. Swinging ball in front of a torch to simulate transits
4. Volunteer swinging an object on a rope to show how Newton’s third law causes a star to wobble – they can’t hold their arm still
5. Demonstrator swinging a tuning fork on string to demonstrate Doppler Effect
6. Shining a laser pointer through a diffraction grating to show how spectra are taken
7. Torch rotating on twisted elastic bands to emulate pulsar jets OR using new pulsar model.
8. Using of Active Expression Handsets to vote on whether/where/how many aliens there are.

Previously included:
• Model planets, possibly held up by volunteers
• Squeezing/stretching a squash ball or elastic band to show heating effect
• Getting volunteers to orbit one another, one holding a torch to illustrate day/night and year

Risk Assessment
Date risk assesment last checked: 
Tue, 06/02/2018
Risk assesment checked by: 
Andrew Sellek
Date risk assesment double checked: 
Tue, 06/02/2018
Risk assesment double-checked by: 
Risk Assessment: 
2a. Scalding/burning from hot water
Let water cool to lukewarm before using in demo. Do not overfill vessels and leave away from edges of tables. Do not handle hot vessels.
In case of scalds/burns contact first aider.
2b. Spillages of water
Leave vessels away from edges of tables where they might be knocked, only handle if comfortable temperature.
If spillage occurs, dry up immediately if safe temperature or cordon off area until safe to do so.
2c. Breaking of glassware or thermometers
Leave vessels away from edges of tables, make sure thermometers will not topple or roll before leaving.
Clear up any breakages and spillages. In case of injury or contact with thermometer contents, call first aider.
3a. Torch being shone in eyes
Use a fairly low power LED torch as these are safe. Demonstrator to ensure torch is stably mounted facing wall.
If someone is dazzled by lights, switch off lights and sit them down until they have recovered. Check they are ok before letting them walk around again!
3b. Ball coming free of attachment
Use low velocities, light bluetack ball.
In case of injury, call first aider
4/5. Swinging object on rope: potential for object to fly off / rope to snap / object to be dropped on foot leading to potential injury or breakages.
Use light object. Only have demonstrator use heavier turning fork – make sure rope securely attached to hand by wrist strap – each object to have suitable attachment to rope. Perform in lots of space and keep low/horizontal.
If causes breakage – clear up any dangers.
If causes injury then contact first aider.
6. Laser pointer being shone in eyes
Only allow demonstrator to touch the laser pointers; point the laser pointers towards the front wall so that nobody is facing the beam; do not shine at mirrored surfaces; ensure everybody is sitting down before shining it so that nobody moves into its path.
In case of accident contact first aider.
7a. Torch being shone in eyes
Since this involves rotating beam, poor direction inevitable. Try to keep pointing downwards and if judged too bright, cover with paper to attenuate.
If someone is dazzled by lights, switch off lights and sit them down until they have recovered. Check they are ok before letting them walk around again!
7b. Flashing lights
Warn before demonstrating that the rotating torch will have the effect of flashing - it can get quite fast. Those sensitive to flashing should look away.
In case of seizure, call first aider.
7c. Elastic bands snapping/torch dropping/swinging into demonstrator.
Don't overwork bands and check before use. Hold torch clear of body and feet.
In unlikely event of injury, call first aider
7d. Fire risk from confined lights in model
Switch off when not in use.
In case of burns call fist aider. In case of fire follow venue RA procedure.
8. Assorted risks due to voting devices
Check separate RA for "Use of active expression handsets"
Follow procedures in RA for "Use of active expression handsets"
Electrical Hazards – kettle, lamp, computer, voting devices
Keep water demos away from electrics. See electrical parts RA
In case of emergency, turn off power at wall and call first aider. See electrical parts RA.
Tripping or falling on dropped planets or squash ball
If using volunteers, ask them not to throw balls or run after them.
If ball dropped, demonstrator (not audience) to pick up immediately. In case of accident contact first aider.
Swallowing of or choking on small parts used for some planets
Don’t give small planets to children.
In case of ingestion, call first aider.
Tripping, falling or feeling dizzy when emulating orbits/diurnal rotation
Ensure that actions are carried out slowly e.g. by walking, not running
If dizziness occurs, sit down until recovered. Call first aider in event of injury.
Elastic band snapping – unlikely possibility of injury
Encourage volunteers not to over stretch bands
In unlikely event of injury, contact first aider.
This experiment contains mains electrical parts, see separate risk assessment.