Francis Everitt was born in Sevenoaks, Kent, in 1934. After a first degree in physics he took a doctorate in palaeomagnetism at Imperial College London in 1960. Then he switched back to physics, and moved to the University of Pennsylvania to work on liquid helium. He also became interested in using gyroscopes cooled to very low temperatures to make sensitive tests of Einstein鈥檚 general theory of relativity. In 1962, testing Einstein became his main focus when he moved to Stanford University in California where the Gravity Probe B experiment was born. As Stanford鈥檚 professor of physics, he has written more than 90 papers and a biography of James Clerk Maxwell
Where were you on launch day last April?
At the launch site, in the control room.
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The rocket had to be launched at exactly the right moment so that Gravity Probe B reached its correct orbit. Were you worried that your life鈥檚 work boiled down to just 1 second?
Very much. The launch had originally been scheduled for the previous day and had been aborted with 3 minutes to go. No one could have stopped the launch if the countdown had carried on for another minute.
How did you feel when the launch was aborted?
It was a let-down. But maybe it wasn鈥檛 such a bad thing after all because it gave everyone a live rehearsal of what was to come. So the real launch was a lot calmer. During the final countdown I had some mystical sense that it was all going to be OK.
So when did you finally relax?
When the Delta 2 rocket separated from Gravity Probe B and a camera on the rocket showed that all the probe鈥檚 solar panels had unfolded. It might not sound like a big deal, but far too many spacecraft have been ruined because of faults with the solar panels. It would have been a dire situation for us.
And how is Gravity Probe B performing now?
We began the science phase of the experiment on 27 August last year and we have been taking data ever since.
Any preliminary results yet?
Until you鈥檝e done all the calibrations, you simply don鈥檛 know. We have an idea of where we are, though.
What got you interested in testing Einstein鈥檚 relativity?
I remember my father discussing Einstein鈥檚 popular book, The Meaning of Relativity at our dinner table when I was 12. I didn鈥檛 realise at the time that we were discussing an issue of great importance in physics, namely the incompatibility of quantum physics and relativity. And I didn鈥檛 know until I was about 17 that my trajectory would be towards physics.
But wasn鈥檛 your early work on rock magnetism and plate tectonics?
I did a degree in physics at Imperial College London and decided to do a PhD. For me, it was a random decision what to do. You talk to some professor and eventually decide that you like what they are doing. My adviser was the Nobel prizewinner Patrick Blackett, whose research was mostly on cosmic rays. But after the second world war, he became interested in magnetism, which led him to invent an extremely sensitive magnetometer for measuring small electromagnetic fields. Blackett realised his magnetometer could measure magnetism in sedimentary rocks. Our group, and another at Cambridge, started looking at rocks whose magnetism had never been studied before. We ended up being the pioneering groups in continental drift studies and palaeomagnetism.
So why did you switch fields?
At the end of five years you have to decide whether you want to turn into a geologist or back into a physicist. As much as I liked geology, I thought I was more naturally a physicist and then I had to start trying to get back into physics.
Was that hard?
I was fortunate to have discussions with some very good people at Imperial College, including Philip Morrison, one of the American physicists who worked on the Manhattan project. And I happened to read a book on liquid helium by Kenneth Atkins at the University of Pennsylvania and was inspired to apply for a position there. I was there for two years learning about physics at low temperatures with liquid helium, which I鈥檇 never seen before.
But where did Gravity Probe B fit in?
I wasn鈥檛 sure I wanted to be working with liquid helium for the rest of my career. At that point, quite a famous physicist from Stanford University called William Fairbank came to Pennsylvania to give some talks. Fairbank had a reputation for trying very difficult experiments. He was in the business of applying low-temperature techniques to other kinds of physics. I remember Atkins saying that Fairbank had gone too far because he had started talking about a gyroscope experiment to test Einstein. I felt that what he was doing was where I should be going.
Looking back, I realise I was enormously influenced by a casual remark made by Blackett: if you aren鈥檛 sure what physics to do next, invent some new technology because it will always led to new physics. One thing led to another, and in 1962 I went to Stanford to work on what became Gravity Probe B.
Why has it taken the probe 40 years to get off the ground?
The fundamental reason is you have to invent technologies and that takes time. NASA concluded that all the necessary technologies had been demonstrated by 1981.
But it still took another 23 years for the probe to launch?
There is an enormous difference between having demonstrated individual technologies and having these technologies integrated, working together in something that can be flown. The original idea was to launch Gravity Probe B from the space shuttle. The space shuttle would fly in a polar orbit and then the probe would be pushed overboard.
So what happened?
That went wrong for two reasons. The programme started in 1985 and a year later, the Challenger space shuttle blew up. At the same time, NASA decided to close down the Western Test Range, which is needed to launch the shuttle into a polar orbit. And Gravity Probe B needs a polar orbit to test two key predictions of Einstein鈥檚 general theory of relativity: how space and time are warped by the presence of the Earth, and how Earth鈥檚 rotation drags space-time around with it. That meant we had to launch Gravity Probe B into space on an expendable rocket.
Which adds to the project鈥檚 cost?
If there had been an ideal funding profile it might have taken about eight years less, not 20 years.
What do you mean 鈥渋deal funding profile鈥�?
For a number of perfectly sensible political reasons, NASA gave Gravity Probe B a fixed number of dollars per year, which isn鈥檛 the way you normally run space programmes. Usually you run a programme so that you have extra funds to play with at the time of the greatest difficulty. That wasn鈥檛 done. So some things that really should have been done in parallel were done sequentially, and that adds to the length of the mission.
What effect did that have on the probe?
Some things were done better because we had more time. On the other hand, having more time puts stress on people. As my colleague Brad Parkinson once remarked, space programmes grind people up.
Did you have difficulty attracting students who might not see the fruits of their labour?
No. And that鈥檚 an interesting factor. We鈥檝e had 79 PhD students: one-third of them physicists and the rest engineers. You can still define worthwhile research programmes relevant to Gravity Probe B that will enable students to get a PhD in reasonable time.
How many times was Gravity Probe B cancelled?
I know of at least seven cancellations. And it turns out there were at least another three times when it was cancelled without my prior knowledge.
How did you get the news about it being cancelled? How did it feel?
The first time it got cancelled was strange. In 1980, President Jimmy Carter decided halfway through the year to try to improve the balance of the US budget. All agencies would therefore have to take a funding cut. Word reached me that something funny might be happening and then I got a phone call at home from a senior person in NASA鈥檚 office of space science at 3 pm. 鈥淔rancis?鈥� he asked. 鈥淎re you sitting down? I have just cancelled your programme. You have four to six weeks to do something about it, but I can鈥檛 tell you what.鈥�
What did he mean?
If you鈥檙e living in the US and someone in the executive branch give you that kind of message, it鈥檚 really a code.
For what?
To go and inform Congress. NASA cannot lobby Congress itself and cannot suggest that you lobby Congress. Maybe I decoded it incorrectly, but that鈥檚 how I decoded it.
Had you been involved in US politics before?
I had been to Capitol Hill once before to listen to a debate, just to see what it was like. But I鈥檇 never been to the Senate. Will Fairbank was a fantastic person to have fighting your corner. He and I went back to Capitol Hill to see the office of the congressman representing the district in Alabama where NASA鈥檚 Marshall Space Flight Center is located鈥搕he centre running our programme.
What happened?
To our astonishment, he was proud to show off his file on Gravity Probe B. This man and one of his colleagues from the science committee gave Fairbanks and me an hour鈥檚 worth of education in how to deal with Congress, explaining the different committees and telling us who to go and see. We went back to Capitol Hill three times. We learned an interesting thing: congressional staff talk to each other and then doors either pop open or close.
鈥淕ravity Probe B has had trouble not because NASA people are evil or anything, there鈥檚 just never been a home for fundamental physics鈥�
And it turned out well鈥�
To cut a long story short, within five weeks the senator and former astronaut Harrison Schmidt asked the NASA administrator at a congressional hearing why on earth it was cancelling such an important mission. NASA got a roasting for having done such a stupid thing and our funding was restored.
Why has Gravity Probe B had so much trouble at NASA?
It is important to say that it鈥檚 not because people at NASA are evil or anything. There has just never been a home at NASA for fundamental physics programmes. That doesn鈥檛 mean that you won鈥檛 get support, it just takes commitment.
So you鈥檝e become a political animal?
The thing I鈥檝e learned is that you have to keep people informed. So I would go to Capitol Hill two or three times a year to let the politicians know that things were coming on nicely with Gravity Probe B. On one or two occasions when a crisis was brewing, I鈥檇 tell them sooner rather than have them hear horrible bad news from someone else.
What advice would you give to physicists involved in massively expensive projects, where politics inevitably plays a huge role?
The world doesn鈥檛 owe you $700 million for Gravity Probe B or any other programme. Still less does it owe you $10 billion for a particle accelerator. The particle physicists who worked on the axed superconducting supercollider in Texas didn鈥檛 seem to understand that. They tended to think that because they had always been funded before their funding should continue.
How have you dealt with critics who say that there are far cheaper ways of testing general relativity than Gravity Probe B?
Look, this whole business of testing general relativity is a curious one. There is something inherently different about Gravity Probe B compared to any previous tests of relativity. It is a physics experiment in contrast to an observation: that means the apparatus is under experimenters鈥� control. In 1919, Arthur Eddington showed that gravity bends light from a star, as Einstein had predicted. He took a telescope to an island to view a solar eclipse and hoped that a cloud didn鈥檛 pass in front of the sun. It was a great result but it was an observation, not an experiment where everything is under your control.
Also, Gravity Probe B has been designed in such a way that all of the non-Einstein effects are very small compared with the Einstein effects. That鈥檚 no criticism of the various other experiments, but in many instances the background effects are enormously larger than what is being measured and the experiments rely on incredibly sophisticated techniques to dig the relativity out. I think that unique aspect of Gravity Probe B is worth it.
Were there times in the past 40 years when you felt like giving up?
In 1980, I鈥檇 been working on Gravity Probe B for 17 years. When I got the news that it had been cancelled, I really did begin to think that the past 17 years of my life were about to go down the drain and I鈥檇 have nothing to show for it. And then I got a mystical feeling that this wasn鈥檛 going to be the case.
You鈥檝e mentioned this mystical feeling before. What is it?
A feeling that it is meant to be. Haven鈥檛 you had that? You need to view these feelings with a reasonable amount of intellectual detachment.
