Clearly your field isn't pure mathematics.

A slide presentation can help you and your audience. Required? Ask your advisor.

@FedericoPoloni I made slides for my thesis defense (symplectic geometry) but also practiced writing on a whiteboard. I could do the slides in 45 minutes (the time limit) but writing on the board, even only what was necessary, pushed it to over two hours.

It is possible to go through a slide presentation very fast, but there may well be a penalty for doing that: Your audience will miss most of your talk. I do not recommend using slides to compress a two-hour talk into 45 minutes.

@AndreasBlass The old joke comes to mind: when you have 25 slides a second, you have a movie. A famous Nobel prize winner was notorious for going through a humongous number of slides during a talk.

Highly field-specific. Every answer is possible, from "yes, pretty normal" to "theoretically possible, but in practice, your advisor will urge you to make one because not having one would be totally outlandish".

You might be in luck if you're a dance major.

@Aruralreader: Dancing with Banach spaces, say, might suffice in some cases. ;-)

We didn't even need a pen back in the days.

You’re right about that. @Buffy was bragging earlier about her slate ppts, bless her heart, but it was a hell of a lot harder to do our PhD orals back in the day before languages were developed! What are these “pens” of which you speak?

Where are you? As well as which field? In the UK, in physical sciences, a presentation isn't the norm, for example

In the UK that is common.You just sit down in a small room with your examiners. Me and most of my peers did not need to make a presentation, it was just sit down and get roasted, skipping formalities.

I'm in the UK and I don't know anyone who's given a presentation. Your examiner might ask you to summarise your work in a couple of minutes at the beginning, but the bulk of the viva is questions. I know a few people who've taken small items in (especially if they've built them themselves), but no slides.

You can defend your thesis with nothing but a stick if you like. What matters is whether you convince the examiners or not.

@J... or a sword of course xkcd.com/1403

@BeginTheBeguine my internal informed me specifically that I wouldn't need to prepare anything, and my supervisor's advice was to be ready to summarise using the thesis itself if I absolutely needed visuals (UK). But the summary was meant to be just that - a summary, and like an abstract, made of words.

@ChrisH Yes, I think it's probably a fairly common first question. It lets you warm up a bit with something you should definitely be able to answer!

@ChrisH ... or a flute: mcsweeneys.net/articles/…

Relevant PhD Comics: phdcomics.com/comics/archive.php?comicid=2034

UK vivas are a true examination. US defenses are a ceremonial talk. They're entirely different beasts.