In the previous two sessions we looked at scientific theories that challenged a literal reading of the bible. Today I want to look at some science that was developed earlier than either of those – perhaps took longer to get to the wider public but in the long run had an even greater effect on beliefs.
So today we are going to have a look at some physics. We are particularly going to look at motion – how things move, how they come to move etc. I am sure many of you are better physicists than I am – feel free to correct me – but what I am really interested in tonight is the effect the physics, and the maths that goes with it, had on our view of the world. So I will be generalizing and simplifying – to try to say something useful in 15 minutes.
Until about the 15th or 16th century – much understanding of physics was based on ideas put forward by Aristotle over 2000 years ago. Ideas that turned out to be wrong – but which many of us still kind of believe – because they seem intuitively right.
- Things that are moving will eventually come to a stop.
- For things to keep moving – they need to keep being pushed.
- Heavier things fall faster than lighter things.
- Things fall because it is their natural state to be on the floor.
These ideas were eventually challenged – particularly as people studied the movements of the planets. One person made a huge contribution to our understanding – Isaac Newton.
Legend has it that he sat in an orchard – an apple fell on his head – and lo…I’m sure there was more to it than this – but apparently he wondered why it fell down, not up or across – in other words, why does it seem that things ‘want’ to be on the floor? This led to his discovery of the force of gravity which we experience pulling things towards the earth.
This idea and many others were explained in his book Mathematical principles of Natural Philosophy published in 1686.
Apart from the idea of gravity, I want very briefly to pick out 3 other things he discovered about how things move – called his Laws of Motion.
- “Every object persists in its state of rest or uniform motion in a straight line unless it is compelled to change by forces impressed on it.”
So if things are still – and we don’t exert a force on them – they won’t move. Seems obvious – but leads to surprising things.
- Jenga – you’ve probably played it – and been amazed by how you can remove one brick without affecting others. You aren’t putting a force on them – so they will stay where they are until it becomes unbalanced.
- There are other ‘tricks’ you can do to demonstrate this – stack of cups, coins, eggs dropping into water. Google ‘demonstrations of Newton’s first law’ and you will find lots on you-tube – including the infamous ‘table cloth trick’.
But also if things are moving – and we don’t stop them – they will go on moving for ever…we don’t need to keep pushing. This is counter-intuitive of course because normally things are stopped by friction but they don’t stop just when we stop pushing them. In space, however – where there is virtually no friction – things keep moving – which is why astronauts on space walks are firmly attached to the space ship!
- For a constant mass – force equals mass times acceleration. F = ma
This is more complicated to demonstrate or explain – but it describes motion – movement – in terms of maths. This means if you know two of the things in that equation – you can calculate the other one. It led to Newton showing that despite what Aristotle – and probably most of us think – if we drop two objects – the heavier one doesn’t fall faster! Again there are lots of demonstrations online.
- For every action there is an equal and opposite reaction.
This again seems odd – but if you push your hand down on a table, the table pushes back at you. The harder you push, the harder you can feel it pushing back. If you sit in an office chair with wheels – and throw a heavy ball away from you – you will move backwards – in the opposite direction to the ball. You push the ball, and the ball pushes you.
Newton’s laws are great for party tricks – but the point about them is that Newton found ways of describing them in maths, and found that in every situation he came across, they worked – which meant they can be used to predict what will happen in certain situations even predicting things that haven’t yet happened…
Edmund Halley used Newton’s Laws to predict the arrival of the comet named after him. He didn’t live to see it – but he was right.
Rosetta probe was launched on 2nd March 2004 – on 12th Nov 2014, after travelling 6.4 billion km, it’s lander landed on a comet 4 km across, travelling at 135,000km per hour… all predicted by Newtonian mechanics!
Newtonian mechanics led to an important idea – every thing that happens has a cause (determinism) nothing is uncertain – we may just not have worked out yet what the cause is.
This evidence for fundamental laws of nature, and the beauty of the universe gave rise to the idea of the ‘Divine Watchmaker’ (if you found a beautiful watch on the floor, you would deduce the existence of a watchmaker) and the feeling that if God created a perfect universe, there is no need for further intervention.
Knowledge of the laws of physics left less room for God as anything but Creator. As Darwin said “the more we know of the fixed laws of nature – the more incredible miracles become.”
So what do we do about miracles?
- Suggest that God just works through our minds – he can persuade but not intervene – and explain the miracles a different way? Loaves and fishes…
- Accept that Jesus could overcome the laws of nature – but assume miracles were only for biblical times?
- Abandon our faith?
- Pretend Newton never existed…
I would like us to have a look at a number of miracle stories from the bible – and think about our reaction to them, what they might tell us about God. I haven’t printed whole stories as there would be far too much to read – I suspect you are all familiar with the stories I’ve chosen.
Bible Study – Miracle stories
There are many miracle stories in the gospels – for example:
Jesus heals the paralysed man (Mark 2)
Jesus feeds 5000 (Mark 6)
Jesus walks on water (John 6)
Jesus raises Lazarus from the dead (John 11)
How do you relate to these miracle stories? Do you find them difficult or easy?
Thinking about previous discussions – in what way do you consider them to be true?
Is it possible to interpret any or all of these in ways that are ‘scientifically plausible’?
If we do this – does it alter our view of Jesus? How?
Perhaps the ultimate miracle story is the resurrection of Jesus (Matthew 28, Mark 16, Luke 24, John 20).
Do you think of this as a miracle – or something else?
There are also miracle stories not involving Jesus directly:
Peter and John heal the crippled beggar (Acts 3)
The apostles heal many people (Acts 5)
Peter is freed from prison (Acts 12)
Paul is freed from prison (Acts 16)
Is it easier or harder to accept these as miracles?
Is it possible to accept miracles and Newtonian mechanics?
Do you think miracles happen today?
Has anything happened to you that you would describe as a miracle?