Analysis of the Nature of Matter (AQA A Level Physics): Revision Note

Analysis of the Nature of Matter

The Evolving Field of Quantum Mechanics

• The field of quantum mechanics is a relatively new field of research, compared to fields in classical mechanics (Newton’s laws, wave theory etc)

• Around 1900, discoveries such as the electron and the gamma photon began to conflict with the existing models scientists held about the nature of matter

• Soon after, new theories about the nature of matter began to emerge from Max Planck, Niels Bohr and Albert Einstein, who are seen as the pioneers of Quantum Theory

• Unsurprisingly, the understanding of quantum mechanics and the nature of matter has changed over time

  • Scientists use the existing models, such as wave theory, to make predictions 

  • Sometimes the results of their experiments were not as predicted and did not fit with the existing model, for example, the photoelectric effect

  • Scientists then have to change the model so that it can explain the new evidence, for example, wave-particle duality

Development of Scientific Theories

• When a new theory is suggested, such as de Broglie’s idea of particles acting as waves, the theory needs to be evaluated

• Other scientists evaluate the theory in a process called peer review

• When enough experimental evidence is found to support the theory, it is validated

• De Broglie’s theory is currently accepted to be correct until any conflicting evidence is found

Peer Review

• Scientists across the world form a scientific community

• Scientific claims from new research that is published in journals must be peer-reviewed or evaluated by other scientists who are experts in that field of science

• During the peer review process, scientists must check:

  • Validity – does the research achieve what it says it does? Is the method appropriate and how have any errors been addressed?

  • Originality – are the results new or has anyone else already carried out similar research? If so, has their work been credited?

  • Significance – are the findings of the research important or ground-breaking?

Evaluating Scientific Claims

• Claims that are from research that is not peer-reviewed should always be questioned

• There could be a multitude of problems. These could be the method used, the accuracy of results or the conclusions drawn

• Research should also be checked that it is:

  • Repeatable by the same scientists who carried it out

  • Reproducible by other teams of scientists

Timeline of the great advancements in quantum theory since 1900