1.35pm: We don't provide live blogs for many birthday celebrations, even 70th ones. But this is the man generally celebrated as the most famous living scientist in the world, someone who has not just provided great advances on thinking about black holes and the study of the early universe, but sold 10m books detailing his thoughts.

This is, of course, Stephen Hawking, the Cambridge University physicist, who was born on 8 January 1942. His life and celebrity are, of course, hard to untangle from the astounding story of how he echieved such feats while living with a form of motor neurone disease. He was famously diagnosed aged just 21 and given just a few years to live by doctors.

Rather than re-hash a lot of detail available elsewhere, here is today's story about the birthday celebrations by my colleague, Alok Jha, who is in Cambridge and will be reporting from the event. And while I'm assuming most people don't need convincing of Hawking's scientific achievements, those who do should read this blush-inducing set of tributes from scientific peers.

1.40pm: So what is on offer today? The main event is a rare public lecture by Hawking himself, the punningly-titled A Brief History of Mine. Other speakers at the celebration, which labours under the formal title of The State of the Universe: Stephen Hawking 70th Birthday Symposium, are Lord Rees, the astronomer royal, Saul Perlmutter, who won the Nobel prize in physics last year for the co-discovery of dark energy, and Professor Kip Thorne, formerly of the California Institute of Technology and a longtime collaborator of Hawking.

There are more details at the event's official website, where those not in Cambridge – like me – can watch a live stream of the event from 2pm-ish.

1.45pm: The chosen hashtage on Twitter, for those who like to follow events through the medium of 140 hastily-typed characters, is #hawking 70. Above is a brief round-up using the magic of Storify.

A number of tweets point to this rather fetching (I think) Lego portrait of the great man.

Photograph: David Fleming

2.00pm: For those who can't wait for the live feed, David Fleming has tweeted this photo of the crowd assembling at Lady Margaret Hall in Cambridge.

2.03pm: You can follow Alok Jha's tweets from inside the hall here. So far he's spotted Richard Branson and is hunting down rumours that Lily Cole might be there, too.

2.05pm: It's started. We begin with an introduction by Cambridge University's vice chancellor, Professor Sir Leszek Borysiewicz.

A reminder to new arrivals: you can watch it all live on this web stream, which so far looks crystal clear and hasn't ground to a halt once. You'd have to hope for that with a scientific lecture, but it's often no guarantee.

2.09pm: Borysiewicz is giving the audience a condensed rundown of Hawking's scientific achivements, and his feats in popularising physics and cosmology. He mentions A Brief History of Time, making the perhaps inevitable follow-on "which we have all tried to read".

2.13pm: Ah. Here's something I should have probably known beforehand. Borysiewicz explains that Hawking has been ill and was only discharged from hospital on Friday and so, for understandable reason, is not attending the symposium as scheduled. He says Hawking should be watching at home, adding:

If you're listening, Stephen, then happy birthday from all of us here today.

This brings loud applause from the audience.

2.16pm: Borysiewicz announces that the university has received an offer to establish and fund a professorship of cosmology named in Hawking's honour. He adds, for a second time in his speech, an appeal for more funding. That's the modern vice-chancellor's job in a nutshell – part leader, part chief tin-rattler.

2.18pm: Lord Rees has begin hia address and is giving historical background on his life in science alongside Hawking.

2.21pm: I'm not to give blow-by-blow accounts of every part of the the speeches, mainly because you can follow them live on the web feed, or via Twitter. Alok Jha, for example, has already sent the above tweets about Rees's speech.

2.24pm: Rees is currently addressing one of the most populist topics in modern science: could there be life on other planets, ands how do we locate it?

2.28pm: Rees shows a chart showing the evolution of life on Earth and mentions, somewhat cheekily, that this is the accepted timeline "unless you live in Kentucky or parts of the Muslim world". The audience chuckle.

2.32pm: I should point out that another regular source of tweets from the event is coming via Katie Scott, associate editor of the Wired.co.uk website.

2.35pm: Here's some news! We're all doomed, says Rees, at least in the end. Alok's tweet, above, explains.

2.38pm: Another tweet from Alok points me to this nicely-put together Storyful (much like Storify) round up of birthday tributes.

2.52pm: Rees is getting deep into the fundamental uncertaintly that underpins his, and Hawking's, science. Alok condenses some of it in tweets:

Our big bang may not be the only one. It could be just one island of spacetime in some vast cosmic archipelago - Rees

Rees wonders if different universes have same laws of physics as ours. If not, others may not have structures such as stars etc #hawking70

2.59pm: Rees just used the phrase "zillions of stars". That's not a real number, is it?

3.07pm: Next up is Saul Perlmutter, who's going to explain – as simply as he can – the science behind his share of the 2011 Nobel Prize for phyics. "It's worth a try," he says.

Alok tweets:

Perlmutter reckons you'll be able to explain dark energy to anyone in the pub after his lecture #hawking70

3.26pm: Perlmutter is an engaging speaker. As I mentioned for Rees, there's little point me giving a full round-up of a speech far better watched live on the web stream. But above are a few recent tweets to give you a flavour.

3.31pm: Breaking away from Cambridge briefly, here's a great cribsheet from my colleague Ian Sample for those pub discussions about what Hawking's discoveries and achievements actually amount to.

3.47pm: There's some more tweets from the talks coming from Lisa Grossman of the New Scientist, who notes this fascinating snippet from Perlmutter's address:

Perlmutter: There's been an avg of *a paper a day for the last 12yrs* (!) w/alternative explanations for dark energy #Hawking70

3.53pm: Perlmutter finishes, to loud applause. What a fascinating speech. He ends with some reflections on how collaborative modern science tends to be, illustrating this with slides of various team photos of the people he works with. Perlmutter says:

If you really want to work with people you should go into science. It's the most social activity I know of.

4.02pm: The live web feed appears to have broken. It's currently showing a re-run of Lord Rees's opening speech. We are still due to hear from a final speaker, Professor Kip Thorne – let's wait and see. I can always try to cover it entirely via Twitter.

4.36pm: We're back, and Kip Thorne has begun speaking. He recounts first meeting Hawking in 1965 – they do go back a long way. Thorne says soon afterwards:

Stephen is, by a large measure, the most stubborn person I have ever met.

That's a compliment, but the way. As with the other addresses, I'll provide the odd highlight or tweet, but for more detail you're far better watching the live stream.

4.43pm: This speech, I should have added, is titled The Golden Age of Black Holes.

4.51pm: This really is another fascinating talk, all you ever wanted to know about black holes and how our knowledge of them has increased. Above are a few tweeted snippets so far.

5.04pm: Thorne is still speaking, but it's perhaps time to bring this live coverage to an end. The plan had been to build up to Hawking's own appearance, a rare public speech by the scientist, but as we learned during the introductory address by Cambridge University's vice chancellor, Professor Sir Leszek Borysiewicz, Hawking was only released from hospital on Friday and remains too ill to attend. He has, hopefully, been able to follow the many birthday greetings.

My colleague, Alok Jha, is still tweeting from the event, and you can follow it live at this web video stream.

5.16pm: I should add, actually, that we will have a story later by Alok about Hawking's own address, which is due to be played to the event at about 6pm-ish (though, obviously, not delivered by the great man himself). We'll post a link to this story when it's up.

7.53pm: You can now read Alok Jha's story about Hawking's speech here.