Before viewing

(Class or group discussion.)

Students may find it useful to pool their existing knowledge of:

• gravity and its effects on the physical world
• how gravity influences the living world

(Students may find it helpful to jot down key words while watching the programme, as a basis for a discussion of the programme’s underlying ideas (see ‘Background’ section).)

(Class or group discussion.)

Discuss what the programme reveals about:

• the effects of gravity on Earth and throughout the Universe
• the difficulty of determining a precise value for the gravitational constant, G
• the influence of gravity on human shape and movement
• changes in scientific ideas about the forces acting in the Universe

(Individual or group activity.)

When Einstein put forward his general theory of relativity, astronomers were sure that the Universe was neither expanding or contracting. To make his theory fit with this static model, he invented a new parameter, a cosmological constant representing a repulsive force.

Edwin Hubble discovered that the Universe is expanding, and the speed at which galaxies are receding is proportional to their distance from us. This discovery overthrew the static model of the Universe, and cast doubt on Einstein’s theory.

Hubble suggested that the two variables — speed (v) and distance (d) — were directly proportional, linked by the Hubble Constant (H), a number which determines the size and age of the Universe.

The Hubble formula looks simple enough:

v = Hd

The bigger the Hubble constant, the faster any particular galaxy must be travelling away from our planet (and from everywhere else), and the less time it will have taken to get to where it is now. So, in terms of the Big Bang model, the higher the value of H, the younger the Universe must be.

Hubble’s original value for H was around 500. Modern techniques have shown this value to be much too high, but there is still no agreed value for H. To calculate it, all we need to know are values for speed and distance.

Why is it so difficult to determine the Hubble Constant?

Why did Hubble’s observations throw doubt on Einstein’s General Theory of Relativity?

What evidence is emerging that Einstein was correct to include a cosmological constant to accommodate the static theory of the Universe?

(Individual or group activity, leading to short presentations.)

Have a look at:
http://members.spree.com/antigravity/index.html

Use the website to build up resources to support a short computer-assisted presentation called ‘Anti-gravity — the propulsive force of the future’.

Activity 4: Are physics and God mutually exclusive?

(Individual or group activity, leading to short presentations.)

Read the lecture transcript at:
http://www.leaderu.com/real/ri9404/bigbang.html

Create a poster or computer-assisted presentation giving your view of whether physics and God are mutually exclusive.