From a not too distant location, this is probably the most convenient way to approach Zürich. There are frequent connections in all directions, from Germany by ICE, from France by TGV, and from Austria by Railjet. Some approximate travel times: Basel (1h), Karlsruhe(3h), Milano (3.5h), Frankfurt (4h), Paris (4h), München (5h), Köln (5h), Utrecht (8h), Berlin (8.5h), Roma (7.5h), Wien (8h), Praha (10h).
Zürich's main station is referred to as Zürich HB. It is located in walking distance (10-15 minutes uphill) to ETH. More details regarding train connections can be inquired from the Swiss Railway Website.
Zürich airport has its own railway station called Zürich Flughafen. The trip from Zürich Flughafen to Zürich HB takes about 10 minutes by train. During peak times, there are 10 connections per hour, after midnight there is still a handful, but between 1:00 AM and 5:00AM there is none.
You must buy a ticket before you board the train. You can buy tickets at a ticket machine or online with the ZVV ticket app.
The route is part of ZVV, the public transport network of Zürich, zones 110 and 121. The tickets are valid for all public transport within these zones, let it be train, tram, bus, or boat. In particular, as Zone 110 includes the city of Zürich, these tickets are also valid for tram or Polybahn (a funicular) that take you from Zürich Central to ETH. Valid here means that you can make as many trips as you like within the given timespan.
There are several ticket options:
If you do not want to go back to the airport within the next 24 hours, a single fare ticket should be your choice. (If you travel within Zürich city later, get the cheaper tickets for CHF 4.40 (single) or CHF 8.80 (day pass) that are valid within Zone 110 only.)
There are also various discount options, such as multi-tickets with six single or day passes, 9 O'Clock day passes, and several touristic tickets. You can find all of these listed and explained in the corresponding booklet "Tickets and Prices" provided by ZVV.
If you want to go from the airport to ETH/the conference site directly, it is more convenient to take Tram #10. Just follow the signs to the tram station. The tickets are the same as explained above for the train, and the trip from Zürich Flughafen to the station ETH/Universitätsspital takes about 35 minutes.
A taxi from Zurich Airport to the city costs about CHF 60-70. To get to the conference site, ask the driver to bring you to ETH Zentrum/CAB, Universitätstrasse 6.
Zürich can easily be reached by car as well. Travel times are similar as given above for train. See any standard routeplanner for details. There is a speed-limit of 50km/h within towns, 80km/h outside tows, and 120km/h on freeways. In order to go on freeways, you need to buy a vignette that costs CHF 40 and is valid for one year. The vignette can be bought at any border crossing or gas station, rental cars usually come with it.
Driving a car within Zürich. This is not really fun, and even less so if you do not know your way. There are lots of one-ways and areas that are not accessible to private cars. Most importantly, there is very little room for parking and it is expensive. Many parking lots are within a so-called blue-zone, for which you need a parking-ticket (Tagesbewilligung Blaue Zone) for each working day incl. Saturdays. Such a ticket costs CHF 15 per day; it can be obtained online from Stadtpolizei (pages in German only). Note that buying a ticket does not guarantee that you will find a parking space.
