An excerpt from Michio Kaku’s “The Future of the Mind”


Chapter Four

Telepathy: A Penny for Your Thoughts

The brain, like it or not, is a machine.  Scientists have come to that conclusion, not because they are mechanistic killjoys, but because they have amassed evidence that every aspect of consciousness can be tied to the brain. –Steven Pinker

           Houdini, some historians believe, was the greatest magician who ever lived. His breathtaking escapes from locked, sealed chambers and death-defying stunts left audiences gasping. He could make people disappear and then re-emerge in the most unexpected places. And he could read people’s minds.

            Or, at least it seemed that way.

            Houdini took pains to explain that everything he did was an illusion, a series of clever sleight-of-hand tricks. Mind reading, he would remind people, was impossible. He was so outraged that unscrupulous magicians would cheat wealthy patrons by performing cheap parlor tricks and séances that he took it upon himself to go around the country exposing fakes. He was even on a committee organized by Scientific American, which offered a generous reward to anyone who could positively prove they had psychic power. (No one ever picked up the reward.)



As we know, the brain is electrical. In general, anytime an electron is accelerated, it gives off electromagnetic radiation. The same holds true for electrons oscillating inside the brain. It sounds like something out of science fiction or fantasy, but humans naturally emit radio waves. But these signals are too faint to be detected by others, and even if we could perceive these radio waves, it would be difficult for us to make sense of them.  But computers are changing all this.  Scientists have already been able to get crude approximations of a person’s thoughts using EEG scans. Subjects put on a helmet of EEG sensors on their head, and concentrate on certain pictures, say, the image of a car or a house. The EEG signals were then recorded for each image and eventually, a rudimentary dictionary of thought was created, with a one-to-one correspondence between a person’s thoughts and the EEG image. Then, when a person was shown a picture of another car, the computer would recognize this EEG pattern.

            The advantage of EEG sensors is that they are non-invasive and quick. You simply put on a helmet containing many electrodes onto the surface of the brain and the EEG can rapidly identify signals which change every millisecond. But the problem with EEG sensors, as we have seen, is that electromagnetic waves deteriorate as they pass through the skull, and it is difficult to locate the precise source. This method can tell if you are thinking of a car versus a house, but it cannot recreate an image of the car. That is where Dr. Gallant’s work comes in.


            The epicenter for much of this research is the University of California at Berkeley, where I received my own Ph.D. in theoretical physics years ago. I had the pleasure of touring the laboratory of Dr. Jack Gallant, whose group has accomplished a feat once considered to be impossible: video taping people’s thoughts. “This is a major leap forward reconstructing internal imagery. We are opening a window into the movies in our mind,” says Dr. Gallant.

            When I visited his laboratory, the first thing I noticed was the team of  young, eager postdoctoral and graduate students huddled behind their computer screens, looking intently at video images that were reconstructed from someone’s  brain scans. Talking to his team, you feel as though you are witnessing scientific history in the making.

            Dr. Gallant explained to me that first, the subject lies flat on a stretcher, which is slowly inserted head first into a huge, state-of-the-art MRI machine, costing upwards of $3 million. The subject is then shown several movie clips (such as movie trailers readily available on YouTube.) To accumulate enough data, you have to sit motionless for hours watching these clips, a truly arduous task. I asked one of the post-docs, Dr. Shinji Nishimoto, how they found volunteers who were willing to lie still for hours on end with only fragments of video footage to occupy the time.  He said the people in the room, the grad students and post-docs, volunteered to be guinea pigs for their own research.

As the subject watches the movies, the MRI machine creates a 3D image of the blood flow within the brain. The MRI image looks like a vast collection of 30,000 dots or voxels. Each voxel represents a pinpoint of neural energy, and the color of the dot corresponds to the intensity of the signal and blood flow. Red dots represent points of large neural activity, while blue dots represent points of less activity. (The final image looks very much like thousands of Christmas lights in the shape of the brain. Immediately, you can see the brain is concentrating most of its mental energy in the visual cortex while watching these videos .)

            At first, this color 3D collection of dots looks like gibberish. But after years of research, Dr. Gallant and his colleagues have developed a mathematical formula which begins to make connections between certain features of a picture (edges, textures, intensity, etc.) and the MRI voxels. For example, if you look at a boundary, you’ll notice it’s a region separating lighter and darker areas and hence the edge generates a certain pattern of voxels. By having subject after subject view such a large library of movie clips, this mathematical formula is refined, allowing  the computer to analyze how all sorts of images are converted into MRI voxels. Eventually, the scientists were able to ascertain a direct correlation between certain MRI patterns of voxels and each picture. “We built a model for each voxel that describes how space and motion information in the movie is mapped into brain activity,” Dr. Nishmoto told me.

            At this point, the patient is then shown another movie trailer while a computer analyzes the voxels generated during the viewing and re-creates a rough approximation of the original image. (The computer selects images from 100 movie clips that most closely resemble the one that the subject just saw and then merges images to create a close approximation.) In this way, the computer is able to create a fuzzy video of the visual imagery going through your mind. Dr. Gallant’s mathematical formula is so versatile that it can take a collection of MRI voxels and convert it into a picture, or it can do the reverse, taking a picture and then convert it to MRI voxels.

            I had a chance to view one of the videos created by Dr. Gallant’s group, and it was very impressive. Watching it was like viewing a movie through dark glasses with faces, animals, street scenes, and buildings: Although you could not see the close-up details, you could clearly identify the kind of object you were seeing.

            Not only can this program decode what you are looking at, it can also decode imaginary images circulating in your head. Let’s say you are asked to think of the Mona Lisa. We know from MRI scans that even though you’re not viewing the painting with your two eyes, the visual cortex of your brain will light up. Dr. Gallant’s program then scans your brain, and flips through its data files of pictures, trying to find the closest match. In one experiment that I saw, the computer selected a picture of the actress Selma Hayek as the closest approximation to Mona Lisa. Of course, the average person can easily recognize hundreds of faces, but the fact that the computer analyzed an image within a person’s brain and then picked out this picture from millions of random pictures at its disposal is still pretty impressive.

            The goal of this whole process is to create an accurate dictionary that allows you to rapidly match an object in the real world with the MRI pattern in your brain.  In general, a  detailed match is very difficult and will take years, but  some categories are actually easy to read just by flipping through some photographs.   Dr. Stanislas Dehaene of the College de France in Paris was examining MRI scans of the parietal lobe, where numbers are recognized, when one of his post-docs  casually mentioned that just by quickly scanning the MRI pattern, he could tell what number the patient was looking at. In fact, numbers create distinctive patterns on the MRI scan.

            This leaves open the question of when we might be able to have picture-quality videos of our thoughts. Unfortunately, information is lost when a person is visualizing an image. Brain scans corroborate this: when you compare the MRI scan of the brain when it is looking at a flower, versus the MRI scan when the brain is thinking about a flower, you immediately see that the second image has far fewer dots than the first. So although this technology will vastly improve in the coming years, it will never be perfect. It reminds of a short story I once read where a man meets a genie who offers to create anything that the person can imagine. The man immediately asks for a luxury car, jet plane, and a million dollars. At first, the man is ecstatic. But when he looks at these items in detail, he sees that the car and the plane have no engines, and the image on the cash is all blurred. Everything is useless. This is because our memories are only approximations to the real thing.

            But given the rapidity with which scientists are beginning to decode the MRI patterns in our brain, does this mean we will soon be able to go beyond seeing the images, to actually reading words and thoughts circulating in the mind?


            In fact, in a building next to Gallant’s laboratory, Dr. Brian Pasley and his colleagues are literally reading thoughts—at least in principle. One of the post-docs there, Dr. Sara Szczepanski, explained to me how they are able to identify words inside the mind.  

The scientists used what is called ECOG (electrocorticogram) technology, which is a vast improvement over the jumble of signals EEG scans produce.  ECOG scans are unprecedented in accuracy and resolution since the signals come directly from the brain tissue and do not pass through the skull.  Of course, the flipside is that one has to remove a large portion of the skull to place a mesh, containing 64 electrodes inside an 8 x 8 grid, directly on top of the exposed brain.

Luckily, these scientists were able to get permission to conduct experiments with ECOG scans on epileptic patients, who were suffering from debilitating seizures.  The ECOG  mesh was placed on their brains while open-brain surgery was being performed on them by doctors at the nearby University of California at San Francisco.

            As the patient hears various words, signals from their brains pass through electrodes and are then recorded. Eventually, a dictionary is formed, matching the word with the signals emanating from the electrodes in the brain. Later, when a word is uttered, one can see the same electrical pattern. It also means that if one is thinking of a certain word, the computer can pick up the characteristic signals and identify it.

  With this technology, stroke victims who are totally paralyzed may be able to “talk” through a voice synthesizer which recognizes the brain patterns of individual words they’re thinking of. It might also be possible to have a conversation which takes place entirely telepathically.  

            Not surprisingly, BMI (brain-machine interface) has become a hot field, with groups around the country making significant breakthroughs. Similar results have been obtained by scientists at the University of Utah in 2011.  They placed two grids, each containing 16 electrodes, over the facial motor cortex (which controls movements of the mouth, lips, tongue, and face) and also Wernicke’s area, which processes information about language.

            The person was then asked to say ten common words, such as “yes and no,”  “hot, and cold,”  “hungry and thirsty,”  “hello and goodbye,” and “more and less.” Using a computer to record the brain signals when these words were uttered, they were able to create a rough one-to-one correspondence between spoken words and computer signals from the brain. Later, when the patient voiced certain words, they were able to correctly identify each one with accuracy from 76% to 90%. The next step is to use grids with 121 electrodes on them to get better resolution.

            In the future, this procedure may prove useful for individuals suffering from stokes or paralyzing illnesses such as Lou Gehrig’s disease, who would be able to speak effortlessly using this brain-to-computer technique.


At the Mayo Clinic in Minnesota, Dr. Jerry Shih has hooked up epileptic patients via ECOG sensors so they can learn how to type with the mind. The calibration of this device is simple. The patient is first shown a series of  letters and told to focus mentally on each symbol. A computer records the signals emanating from the brain as it scans each letter. As with the other experiments, once this one-to-one dictionary is created, it is then a simple matter for the person to merely think of the letter, and the letter would be typed on a screen, using only the power of the mind.

Dr. Shih says that the accuracy of his machine is nearly 100%. Next, Dr. Shih believes that he can create a machine which records images that patient’s conceive in their minds, not just words. This could have applications for artists and architects, but the big drawback of ECOG technology, as we have mentioned, is that it requires opening up the brain of patients.

Meanwhile, EEG typewriters, because they are non-invasive, are actually entering the marketplace. They are not as accurate as ECOG typewriters, but they have the advantage they can be sold over the counter. Guger Technologies, based in Austria, recently demonstrated an EEG typewriter at a trade show. According to their officials, it takes only 10 minutes or so for a person to learn how to use this machine, and then they can type at the rate of 5 to 10 words per minute.




            In science fiction, we often encounter telepathy helmets. Put them on, and presto! You can read other people’s minds. The U.S. Army, in fact, has expressed interest in this technology. In a firefight, with explosions going off and bullets whizzing overhead, a telepathy helmet could be a life saver since trying to bark orders amid the sound and fury of the battlefield drowns out your voice. (I can personally testify to this. Years ago, during the Vietnam War, I served in the U.S. Infantry. During machine gun training, the sound of hand grenades and rounds of bullets guns going off on the battle field was deafening; it was so intense I could not hear anything else. Later, there was a loud ringing in my ear that lasted for three days.) With a telepathy helmet, a soldier would mentally communicate with his platoon amidst all the thunder and noise.

            Recently, the Army gave a $6.3 million grant to Dr. Gerwin Schalk at Albany Medical College, but the Army knows that a fully-functional telepathy helmet is still decades away. Dr. Schalk experiments with ECOG  technology, which, as we have seen, requires placing a mesh of electrodes directly on top of the exposed brain of epilepsy patients undergoing surgery. With this method, his computers have been able to recognize vowels and 36 individual words inside the thinking brain. In some of his experiments, he approached 100% accuracy. But at present, this is still impractical for the U.S. Army, since it requires removing part of your skull in a clean, sterile environment of a hospital. And even then, recognizing vowels and a hand full of words is a far cry from sending urgent messages to headquarters in a firefight. But this ECOG experiment demonstrated that it was possible to communicate mentally on the battlefield.

            Another method is being explored by Dr. David Poeppel of NYU. Instead of opening up the skull of his subjects, he is using MEG technology, using tiny bursts of magnetic energy to zero in on specific regions of the brain. Besides its non invasive nature, the advantage of MEG technology is that it can precisely measure fleeting neural activity, in contrast to the slower MRI scans. In his experiments, he has been able to successfully record electrical activity in the auditory cortex when people think silently of a certain word. But the drawback is that it still requires the use of large table-sized machines to generate a magnetic pulse.

            Obviously, one wants a method which is non-invasive, portable, and accurate. Dr. Poeppel hopes his work with MEG technology will complement the work being done using EEG sensors, but he admits that a true telepathy helmet is still several decades away because both MEG and EEG scans lack accuracy.


            At present, one is hindered by the relatively crude nature of the instruments. But, as time goes by, more and more sophisticated instruments will probe deeper into the mind.  The next big breakthrough may be MRI machines that are hand-held.

            The reason why MRI machines have to be so huge right now is because you need a uniform magnetic field to get good resolution. The larger the magnet, the more uniform you can make the field, and the better accuracy one finds in the final pictures. However, physicists know the exact mathematical properties of magnetic fields (they were worked out by physicist James Clerk Maxwell back in the 1860s).  In 1993 in Germany, Dr. Bernhard Blumich and his colleagues created the world’s smallest MRI machine, which is the size of a briefcase. It has a weak and distorted magnetic field, but supercomputers can analyze the magnetic field and correct for this, so that the device produces realistic 3D pictures.  Since computer power doubles roughly every 18 months, they are now small and powerful enough to analyze the magnetic field created by the briefcase-sized device and compensate for its distortion.

            As a demonstration of their machine, in 2006 they were able to take MRI scans of Otzi, the “iceman” who was frozen in ice about 5,300 years ago toward the end of the last ice age. Because Otzi was frozen in an awkward position, with his arms spread apart, had proven impossilbe to cram him inside the small cylinder of a conventional MRI machine, but Dr. Blumich’s portable MRI machine easily took MRI photographs.

            These physicists estimate that, with increasing computer power, an MRI machine of the future might be the size of a cell phone. The raw data from this cell phone would be sent wirelessly to a supercomputer, which would process the data from the weak magnetic field and then create a 3D image.  (So the weakness of the magnetic field is compensated by the increase in computer power.) This then could vastly accelerate research. “Perhaps something like the Star Trek tricorder is not so far off after all,” Dr. Blumich has said. (The Tricorder is a small, handheld scanning device that gives instant diagnoses of any illness.) In the future, you may have more computer power in your medicine cabinet than in a modern university hospital today.  Instead of waiting to get permission from a hospital or university to use an expensive MRI machine, one could gather data in your own living room by simply waving the portable MRI over yourself and then e-mailing the results to a lab for analysis.

            It could also mean that, at some point in the future, an MRI telepathy helmet might be physically possible, with vastly better resolution than the EEG scan.


            When hearing of mind-reading machines for the first time, the average person might be concerned about privacy. The idea that a machine concealed somewhere may be reading our intimate thoughts without our permission is unnerving.

Fortunately, the laws of physics makes it exceedingly difficult to decode brain scans from a distance. In school, we learned about Newton’s laws and that gravity diminishes as the square of the distance. So that if you doubled your distance from a star, the gravity field diminishes by a factor of four, but magnetic fields diminish much faster than the square of the distance. Radio signals degrade quite rapidly outside the brain especially in uncontrolled environments. Most signals decrease by the cube or quartic of the distance so if you double the distance from an MRI machine, the magnetic field goes down by a factor of 8 or more.

 Furthermore, there would be interference from the outside world, which would mask the faint signals coming from the brain. This is one reason why scientists require strict, laboratory conditions to do their work, and even then they are able to extract only a few letters, words, or images from the thinking brain at any given time. So unless someone is in a laboratory setting and just a foot or two away, the radio signals would be too diffuse and weak for anyone to make sense out of them.

And today’s technology is not adequate to record the avalanche of thoughts that often circulate in our brain as we simultaneously consider several letters, words, phrases or sensory information, so using these devices for mind reading as seen in the movies is not possible today or for decades to come.

            For the foreseeable future, brains scans will continue to require close access to the human brain in laboratory conditions. But in the highly unlikely event that someone finds a way to read thoughts from a distance, you still have countermeasures you can take. To keep your most important thoughts private, you might have to use a shield to block brain waves from entering the wrong hands. (This is done via something called a Faraday cage, invented by the great British physicist Michael Faraday in 1836, although the effect was first observed by Benjamin Franklin.

Basically, electricity will rapidly disperse around a metal cage, such that the electric field inside the cage is zero. To demonstrate this, physicists sometime enter a metallic cage and then fire huge electrical bolts at it.  Miraculously, the physicist is unscratched. This is why airplanes can be hit by lightning bolts and why cable wires are covered with metallic threads.  A telepathy shield would consist of thin metal foil placed around the brain.)


For now, the real question is not whether someone will be able to read our thoughts secretly from a remote, concealed device, but whether we will willingly allow our thoughts to be recorded. What if some unscrupulous person gets unauthorized access to those tapes? Dr. Brian Pasley says “There are ethical concerns, not with the current research, but with the possible extensions of it. There has to be a balance. If we are somehow able to decode someone’s thoughts instantaneously that might have great benefits for the thousands of severely disabled people who are unable to communicate right now. On the other hand, there are great concerns if this were applied to people who didn’t want that”.

Once it becomes possible to read people’s minds and make recordings, then a host of ethical and legal questions will arise. This happens whenever any new technology is introduced and historically, it has taken years before the law is fully able to address their implications.

For instance, copyright laws may have to be re-written. What happens if someone steals your invention by reading your thoughts? Can you patent your thoughts?  Who actually owns this idea?

Another problem occurs if the government is involved.  As John Perry Barlow, poet and lyricist for the Grateful Dead  once said, “relying on the government to protect your privacy is like asking a peeping tom to install your window blinds.” Under interrogation, would the law be allowed to read your thoughts?  Already, courts have been ruling on cases where an alleged criminal refused to submit his DNA as evidence. In the future, will the government be allowed to read your thoughts without your consent, and if so, will it be admissible in court and how reliable would they be in the first place? In the same way that MRI lie detectors only measure increased brain activity, it’s important to note that thinking about a crime and actually committing one are two different things.  Under cross examination, a lawyer may argue that these thoughts were just random musings and nothing more.

There is no law of physics which can resolve these ethical questions. Ultimately, as this technology matures, these issues will have to be settled in court by judges and juries.


An excerpt from Michio Kaku's "The Future of the Mind"