We are now able to deduce the Lorentz transformation, relating two inertial frames. We examine three paradoxes, namely the famous twins paradox, the pole-in-the-barn paradox, and the so-called Bell's spaceships paradox. We also take another look at the relationship with electromagnetism.

We look at the immediate consequences of the two axioms, and discover, qualitatively and then quantitatively, the phenomena of length contraction and time dilation.

We survey relativity's contact with experiment and observation, briefly discussing the classical tests of SR and of GR, and including a discussion of the famous 1919 Dyson-Eddington observations of the bending of starlight during the solar eclipse. In the latter, we look at the historical and social pressures on the scientists involved, and what effect these have on the processes of theory choice.

A brief recap of some mathematical topics.

Inwe saw how observers could make measurements of lengths and times in frames which are in relative motion, and reasonably disagree about the results – the phenomena of length contraction and time dilation. In , we were able to put numbers to this and derive a quantitative relation, Eq. (), between the duration of a ‘tick’ of the light clock as measured in two frames. We want to do better than this, and find a way to relate the coordinates of any event, as measured in any pair of frames in relative motion. That relation – a transformation from one coordinate system to another – is the Lorentz transformation (LT). The derivation inhas a lot in common with the account given in .

In this chapter, I am going to introduce the two axioms of Special Relativity. These axioms are, to an extent, the only new physics introduced in this text: once I have introduced them and made them plausible, the rest of our work is devoted to examining their consequences, and the way in which they change the physics we are already familiar with.

I provide a checklist/recipe for doing relativity calculations.

This chapter starts by arguing that traditionally the writing of history has a strong connection to the construction of identities, be they national, class, ethnic, gender or spatial identities. The theory of history has also re-inforced that link until a range of diverse thinkers came to question this. I am discussing in particular Hayden White, Michel Foucault, Mikhail Bakhtin, Chris Lorenz, Chantal Mouffe, Michel de Certeau, Pierre Bourdieu, Stuart Hall, Roland Barthes, Jacques Lacan and Jacques Derrida. The collective impact of these authors has been to produce a greater self-reflexivity about the relationship between history and identity formation in many historians. The book, however, is not about a whiggish story of progress towards self-reflexivity, but it highlights that work which, in the author’s view, has been successful in being self-reflective about the historians’ part in the construction of identities.

This chapter starts by asking ‘What is in a Thing?’ It discusses the material presence of the past and its rediscovery, for example, in the history of commodities. Material culture history, it argues, has been critical of the linguistic turn but is still building on insights from it. It proposes that objects provide an ‘order of things’ (Michel Foucault), which is in need of examination and contextualisation. At the same time material culture history has also been in the vanguard of decentring human agency and problematising the ‘Anthropocene’. Using non-representational theory, it has been arguing in favour of recognising the agency of things and decentring human agency in history. Material culture history has also been pointing to the longevity of material objects, providing them with often malleable and multiple meanings. It is striking how prominent everyday objects are in material culture histories. Through them individual identities are often related to larger collective identities. Historians of material culture have contributed to raising our awareness of the link between objects and collective identity formation. Examples from national history, environmental history, first nations hsitory, the history of ethnic minorities, colonial history, cultural history, design history, architectural history, regional history, class history, gender history and religious history are all discussed in oder to underline the potential of material culture history to lead to greater self-reflexivity among historians about their role in constructing forms of collective identity and to deconstruct these identities.