Craig Hogan is obviously a trailblazer. He was part of the High-z Supernova Search team that discovered dark energy, two of whose members were awarded the 2011 Nobel Prize in physics for the breakthrough. And measured in productive scientist years, Hogan is still somewhat a pup, as evidenced by his apparent 45-mile Chicago drone commute to Fermilab, where he serves as director of the Center for Particle Astrophysics. So Hogan has plenty of time to find the holographic noise he’s been looking for, for a half dozen years or so, having now reconfigured his original holometer space probe instrument that DOE invested $2.5M in. Hogan is no quitter, he’s pressing on, as he tells me in the interview that follows:
“[I]t’s not fair to say that it’s time to give up because there are very few experiments, and our experiment is the only one of its kind . . . I think you should give us a little bit of time to look for it.”
Hogan says that his main motivation is “this principle of holographic information” and that he and his team have adjusted the experiment to now be “sensitive to rotations.”
Hogan has a point about his experiment being the only one of its kind. The field is rife with theory and often comes down to showmanship. Theoretical physicist Leonard Susskind’s antics may be the most flagrant.
As widely reported, Susskind, a co-inventor of the holographic principle, threatened to slit his own throat if Hogan found holographic noise. Susskind once threatened me saying that if I ever published the transcript of our 20-minute taped telephone conversation he agreed to, in which he said that everything he knew about evolution he learned from reading Richard Dawkins’ book and then proceeded to describe two other giants of biology as nut cases, that he would—. He never finished the sentence, never said specifically what he’d do if I published it. Ironically, another leading theoretical physicist I interviewed told me he based part of his cosmology theory on the thinking of one of the biologists Susskind trashed in the interview.
I first contacted Susskind as a followup to his statement at the 2008 World Science Festival regarding a biological and evolutionary element in physics. Said Susskind at WSF: “I wouldn’t underestimate the biological elements to it also or the evolutionary element to it,” and “what we have to get down to is what the DNA is in the universe.”
But back to hands-on science. Hogan’s holometer was inspired by the interferometer that Nobel laureate Albert Michelson invented over a hundred years ago, which was essentially made of mirrors and a light beam splitter.
Hogan’s holometer was built with two interferometers designed to split incoming laser light. The plan was to get the two interferometers in their cosmic probe to simultaneously “jitter,” which would confirm quantum uncertainty in space-time. Hogan and his team have now, as mentioned, moved some of the holometer parts around to get a “different form of holographic noise.”
Aside from his drone-flight crash helmet, Craig Hogan wears several other hats. Since 2008, he’s been an astronomy and astrophysics professor at Enrico Fermi Institute and at Kavli Institute for Cosmological Physics, University of Chicago, as well as director of the Center for Particle Astrophysics at Fermi National Accelerator Laboratory.
Prior to Chicago, for a decade and a half, Hogan’s base was the University of Washington, where he taught astronomy and physics, chaired the department and served as University of Washington’s Vice Provost for Research, as well as Divisional Dean of Natural Sciences at the school’s College of Arts and Sciences. He taught astronomy at the University of Arizona for five years before that and was an astronomer at the university’s Steward Observatory.
Some of his awards include the 2015 Breakthrough Prize in Fundamental Physics (co-recipient; $3M awarded to Craig Hogan as a member of the High-z Supernova Team split with 50 other scientists for their “most unexpected discovery that the expansion of the universe is accelerating”); Gruber Cosmology Prize (co-recipient, discovery of dark energy, 2007); Alexander von Humboldt Research Award (1999-2008); Distinguished Scientist, Fermilab (2004); Discovery of the Year, Science magazine (1998, as a member of the High-z Supernova Team for the discovery of dark energy) (partial list).
Hogan has chaired and been a member of NASA’s Astrophysics Subcommittee as well as its Space Science Advisory Committee. He was also part of NASA’s Roadmap teams (2005; 2001-2002). From 2001-2011 Hogan was a US member of LISA (Laser Interferometer Space Antenna) International Science team looking for gravitational waves. In 2009, he was elected a Fellow of the American Academy of Arts & Sciences and the American Physical Society, among other professional honors.
Craig Hogan grew up in California and attended public high school. His BA is in astronomy, summa cum laude, from Harvard University and his PhD in astronomy from King’s College, University of Cambridge. He was a postdoctoral fellow at Cambridge, University of Chicago and at California Institute of Technology.
He is a co-founder of the Large Synoptic Survey Telescope Corporation, and author of the book The Little Book of the Big Bang, featuring a foreword by Sir Martin Rees, his PhD advisor at Cambridge. Rees has been quoted as saying:
“Craig has forged unusually original and versatile theoretical insights into astrophysics. If you look at any number of subjects—from dark energy to how the Universe began—you’ll find the earliest papers are from Craig.”
Our interview follows.
Suzan Mazur: You haven’t found the quantum jitter you were probing for with the holometer and now have new instruments you’re using to probe for “rotational quantum twists of space.” Is that right?
Craig Hogan: Yes. In fact, the new instrument is almost exactly the same as the old one. The only difference is that we shifted some parts around so the light beams have a different configuration. It’s designed, like you said, to be sensitive to rotations, which the first one was not.
Suzan Mazur: The rotational quantum twist of space would tell us that real space is not a continuum?
Craig Hogan: Well, yes. It doesn’t have an infinite amount of information like an infinitely divisible space would. That’s sort of just the tip of the iceberg. What it really is telling you is a lot of things.
People sometimes say there’s no such thing as absolute space in relativity. But actually there is. There is very much an absolute local inertial frame and that’s the one that isn’t rotating.
No matter how small a piece of space you go to, you can tell whether you’re spinning around or not because of the centrifugal force if you spin around. But the existence of that is something that might not actually be exact. As you go to smaller scales the definitions of directions, things we’re used to as properties of space, might just dissolve into a quantum system.
Suzan Mazur: Thank you. You’ve said the holometer will be a template for a whole new field of experimental science. My understanding is that your view of geometry in space-time is a minority view. Would you comment?
Craig Hogan: Some of the things we’re looking for are completely standard. My main motivation for it is this principle of holographic information, which is very widely believed in the community of black holes and quantum gravity.
The thing that isn’t agreed upon is what effects that should have on an experiment. Nobody knows. And so we’re just looking to see.
What we know is that the standard theory leaves something out. Everybody agrees with that. It leaves out something important, large scale. Everybody agrees with that. We know that from the behavior of black holes and from the cosmological constant. So the only disputed thing that is controversial is the idea that maybe that thing that we leave out on large scale is something we might actually be able to measure.
Suzan Mazur: The current thinking is that space-time is emergent, it’s 2D sheets encoding a 3D environment?
Craig Hogan: That’s a very widely held view. There are a lot of differences among people as to what is meant by emergence. What is generally agreed upon is that there is missing information, which means there have to be extra correlations. But nobody knows how it works.
However, it’s not like anybody actually has a theory that predicts that we won’t see something in the experiment. If we see something, it doesn’t actually disprove anybody’s theory. Even though some people are saying that it will. But they don’t actually make predictions. It’s a very difficult field that way.
Suzan Mazur: Leonard Susskind has said it’s unclear whether the 3D we think we’re experiencing is here or out there in space. What are your thoughts about that?
Craig Hogan: In a way we know that it’s everywhere because the structure of space and time is built on light cones. Surfaces containing information connect all events at the speed of light. So, what you regard as here and now, the edge of the now extends forever at the speed of light into the future and the past.
Again, it’s currently standard thinking in quantum mechanics that if you do a measurement at one place in the universe, that instantly affects things happening elsewhere—acausal correlations. That’s been proven in many experiments in quantum mechanics. We know in quantum physics that nothing ever happens at a definite place and time— there is no such thing as locality. It has to be defined by physical measurement. All this is very weird but, in effect, totally non-controversial.
Suzan Mazur: Thank you. There is criticism that the holographic investigation has been going on for almost 20 years, kicked off by Juan Maldacena and that there’s very little evidence so far, despite the bold headlines. That at some point in scientific investigations if the data doesn’t correlate with the experiment as modeled, it’s time to move on.
I gather you don’t share that perspective. You’ve said you’re only at the beginning of the investigation. Do you see this as an emerging field like origin of life, spawning an increasing number of virtual research hubs in various parts of the world?
Craig Hogan: That’s very interesting. It’s true this holographic idea has been around even before Maldacena. The basic idea goes back to the 1970s and black hole entropy and Stephen Hawking. But it’s not fair to say that it’s time to give up because there are very few experiments, and our experiment is the only one of its kind. It’s not like there’s a worldwide program of experiments testing this stuff. I think you have to try to look for it before you give up. We haven’t really been looking that long. We have a small team working on this for less than 10 years. I think you should give us a little bit of time to look for it.
If it isn’t there, we’ll know that within a year or two. And we’ll move on. Then maybe somebody else will try again.
Suzan Mazur: You’re the only team with specific instruments probing.
Craig Hogan: Yes, for this particular type of thing, for this particular effect.
Suzan Mazur: So you don’t you see your initiative beginning to inspire other experiments and other research centers.
Craig Hogan: It will depend on whether we’re successful. If we get a null result from the experiment we have, it should be able to go well beyond the Planck length of sensitivity. If we don’t see anything, that’s basically the end of it. If we do, then there will definitely be significant followup.
Suzan Mazur: How close is the goal of combining Einstein’s theory of relativity and quantum theory? Something that’s been described by Kostas Skenderis at University of Southampton as being a new paradigm for physical reality.
Craig Hogan: I’m not sure that a single goal is well defined. There are several fundamental contradictions between the model of space-time that we use, Einstein’s theory of relativity, and quantum mechanics. I think we can expect to circumvent some of those fairly soon and not others. It won’t be completely solved for a long time.
Suzan Mazur: How does this focus intersect with current research into origin of life? There’s no real consensus on what life is. Does this throw an additional wrench into the investigation of origin of life?
Craig Hogan: Of course I’m not really a specialist in biology. But in my view, it’s the behavior of atoms and molecules. Details are necessary to fill in, but that’s basically what it is.
Those are all quantum systems—the atoms and molecules. It’s true that we don’t know how much inherently quantum mechanical behavior that we’re talking about, how important that is to life. Some people think it is. It’s just not that clear what the dependence is.
Suzan Mazur: But you think the 3D existence is real that we’re living in.
Craig Hogan: It’s 4D, of course. Three dimensions of space and one of time. We’ve known for 100 years that they’re not really separate, time and space. So probably time is connected with one of the space dimensions. In that sense the four dimensions are really three dimensions. That’s where the holographic idea comes from. You are kind of down one dimension because of the fact that time and space are interrelated in a certain way. Nothing ever moves faster than the speed of light. That’s built into the system.
Suzan Mazur: Is Templeton also funding, in part, the new aspect of your investigation?
Craig Hogan: We used the Templeton money to fund our graduate students working on the experiment that we’re now just finishing up. We’ve reconfigured our instruments to be sensitive to rotations—to a different form of holographic noise—without spending any extra money. So we’re not looking for new funding yet. We will be, if we get a result.