Saturday, October 17, 2015

Is the World Real?

Is this real life? How do we know that we are not hallucinating it all? What if we're plugged into a Matrix-style virtual reality simulator? Isn't the universe a giant hologram anyway? Is reality really real? What is reality?

We asked renowned neuroscientists, physicists, psychologists, technology theorists and hallucinogen researchers if we can ever tell whether the "reality" we are experiencing is "real" or not. Don't worry. You're going to be ok.

Jessica L. Nielson, Ph.D., Department of Neurosurgery, Postdoctoral Scholar, University of California, San Francisco (UCSF), Brain and Spinal Injury Center (BASIC)

What is our metric for determining what is real? That is probably different for each person. One could try and find a consensus state that most people would agree is "real" or a "hallucination" but from the recent literature using imaging techniques in people who are having a hallucinatory experience on psychedelics, it seems the brain is hyper-connected and perhaps just letting in more of the perceivable spectrum of reality.

When it comes to psychosis, things like auditory hallucinations can seem very real. Ultimately, our experiences are an interpretation of a set of electrical signals in our brains. We do the best to condense all those signals into what we perceive to be the world around us (and within us), but who is to say that the auditory hallucinations that schizophrenics experience, or the amazing visual landscapes seen on psychedelics are not some kind of bleed through between different forms of reality? I don't think there is enough data to either confirm or deny whether what those people are experiencing is "real" or not.

Sean Carroll, Cosmologist and Physics professor specializing in dark energy and general relativity, research professor in the Department of Physics at the California Institute of Technology

How do we know this is real life? The short answer is: we don't. We can never prove that we're not all hallucinating, or simply living in a computer simulation. But that doesn't mean that we believe that we are.

There are two aspects to the question. The first is, "How do we know that the stuff we see around us is the real stuff of which the universe is made?" That's the worry about the holographic principle, for example -- maybe the three-dimensional space we seem to live in is actually a projection of some underlying two-dimensional reality.

The answer to that is that the world we see with our senses is certainly not the "fundamental" world, whatever that is. In quantum mechanics, for example, we describe the world using wave functions, not objects and forces and spacetime. The world we see emerges out of some underlying description that might look completely different.

The good news is: that's okay. It doesn't mean that the world we see is an "illusion," any more than the air around us becomes an illusion when we first realize that it's made of atoms and molecules. Just because there is an underlying reality doesn't disqualify the immediate reality from being "real." In that sense, it just doesn't matter whether the world is, for example, a hologram; our evident world is still just as real.

The other aspect is, "How do we know we're not being completely fooled?" In other words, forgetting about whether there is a deeper level of reality, how do we know whether the world we see represents reality at all? How do we know, for example, that our memories of the past are accurate? Maybe we are just brains living in vats, or maybe the whole universe was created last Thursday.

We can never rule out such scenarios on the basis of experimental science. They are conceivably true! But so what? Believing in them doesn't help us understand any features of our universe, and puts us in a position where we have no right to rely on anything that we did think is true. There is, in short, no actual evidence for any of these hyper-skeptical scenarios. In that case, there's not too much reason to worry about them.

The smart thing to do is to take reality as basically real, and work hard to develop the best scientific theories we can muster in order to describe it. (...)

George Musser Jr., Contributing editor for Scientific American magazine, Knight Science Journalism Fellow at MIT 2014–2015

The holographic principle doesn’t mean the universe isn't real. It just means that the universe around us, existing within spacetime, is ​CONSTRUCTED​ out of more fundamental building blocks. "Real" is sometimes taken to mean "fundamental", but that's a very limited sense of the term. Life isn't fundamental, since living things are made from particles, but that doesn’t make it any less real. It’s a higher-level phenomenon. So is spacetime, if the holographic principle is right. I talk about the holographic principle at length in my book, and I discuss the distinction between fundamental and higher-level phenomena in a recent blog post.

The closest we come in science to "real" or "objective" is intersubjective agreement. If a large number of people agree that something is real, we can assume that it is. In physics, we say that something is an objective feature of nature if all observers will agree on it - in other words, if that thing doesn’t depend on our arbitrary labels or the vagaries of a given vantage point ("frame-independent" or "gauge-invariant", in the jargon). For instance, I'm ​not entitled to say that my kitchen has a left side and a right side, since the labels "left" and "right" depend on my vantage point; they are words that describe me more than the kitchen. This kind of reasoning is the heart of Einstein's theory of relativity and the theories it inspired.

Could we all be fooled? Yes, of course. But there's a practical argument for taking intersubjective agreement as the basis of reality. Even if everyone is being fooled, we still need to explain our impressions. An illusion, after all, is entirely real - it is the ​INTERPRETATION of the illusion that can lead us astray. If I see a smooth blue patch in the desert, I might misinterpret the blue patch as an oasis, but that doesn’t mean my impression isn't real. I'm seeing something real - not an oasis, but a refracted image of the sky. So, even if we're all just projections of a computer simulation, like The Matrix, the simulation itself has a structure that gives it a kind of reality, and it is ​OUR​ reality, the one we need to be able to navigate. (The philosopher Robert Nozick had a famous argument along these lines.)

by Marina Galperina, Hopes and Fears | Read more:
Image: Erin Lux