Can we fully simulate the reality for a Brain in the Vat (BIV)?

For example i clone myself and connect the clone's brain to a very sophisticated computer, which simulates a part of the universe (for example the planet Earth) for it. The simulation should be 100% authentic, in other words, my clone's character in the virtual reality should experience the same impact of fundamental interactions (like gravity), same behaviour of classical and quantum mechanics, same mathematical and logical laws and so on.

I see only 2 ways to do that. Either i should fully comprehend the workings of the universe to create a virtual universe with the exact arrangement; but i fear that it's not possible to have a full knowledge of these fundamental workings. Or i should create such mechanism, that somehow recreates the structure and behavior of our universe in the virtual reality, but i doubt it's even possible in theory.

Considering the above, is it possible (in theory only, as a thought experiment) to create a full or partial yet authentic copy of our universe in a virtual reality and is it possible for dwellers of this virtual universe to create their own universe the same way recursively?

I want to emphasize that i'm not asking if it is possible or practical to create a BIV. Rather i want to ask if it is possible to fool the BIV, that the reality around it is real and make it impossible for the BIV to deduce the unreality of its virtual universe.

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    Why create a physical clone ? any simulator of such power can also simulate it. Isolated from totality of universe both setups will be equivalent.
    – user2411
    Jan 20 '13 at 13:33
  • Getting something to work like the human brain is a much more daunting task than fooling such a brain into thinking that the physics of its virtual world is reasonable. Your concerns are misplaced.
    – Rex Kerr
    Jan 21 '13 at 11:40

My clone's character in the virtual reality should experience the same impact of fundamental interactions.

Someone might argue that if there is no empirical evidence to appeal to in order to establish whether brains in a computer model of the world that can simulate human conscience, then the hypothesis is metaphysical. Many philosophers would maintain that such metaphysical possibilities do not amount to pragmatic cases of doubt: At present, it is physically impossible to make a computer model of the world that can simulate human cognition and replicate the qualitative phenomenology of a human conscience.

The hard problem of consciousness is why or how does some particular brain process produce that particular taste or visual sensation? It is difficult to see any real explanatory connection between specific conscious states and brain states in a way that explains just how or why the former are identical with the latter. There is therefore an explanatory gap between the physical and mental. This difficulty in explaining consciousness is unique; that is, we do not have similar worries about other scientific identities, such as that “water is H2O” or that “heat is mean molecular kinetic energy.” There is an important sense in which we can’t really understand how physicalism could be true. The existence of a "hard problem" is controversial and has been disputed by some philosophers. For philosophers who assert that consciousness is nonphysical in nature, there remains a question about what outside of physical theory is required to explain consciousness.

Consciousness is especially resistant to explanation in physical terms because of the inherent differences between our subjective and objective modes of understanding. But why we must be deluded by schizophrenic and LSD hallucinations to empathetically take on an experiential perspective understanding? Is subjective understanding necessary to make objective science? Some physicists, argue that an interpretation is nothing more than a formal equivalence between sets of rules for operating on experimental data, thereby implying that the whole exercise of interpretation is unnecessary, for example in quantum physics. Any modern physic's scientific theory requires at the very least an instrumentalist description that relates the mathematical formalism to experimental practice and prediction.


This might be a stupid argument (I thought of it myself) so feel free to disprove me if I am wrong. The brain is not only functioning from electrical stimulation. Chemistry affects the brain as well. You can know you are not a brain-in-a-vat simply by doing some sort of mind-altering drug. These drugs affect neurochemicals in the brain (chemicals, not electricity) and produce their obvious effects. I don't see how a brain-in-a-vat who thinks it is drinking alcohol could actually feel the effects of it without the chemical being present. I'm only a college student studying economics so I can obviously be wrong but those are my thoughts.

  • The fluids in the vat may be providing the chemical stimulation, but I like the argument. If you do come up with references to those who take a similar view this would strengthen your answer and give the reader a place to for more more information. Regardless, welcome! Jun 22 '19 at 8:29

I don't think so considering that consciousness cannot be an illusion, therefore definitely not simulatable. The simulation hypothesis is just a fairytale created by bad philosophy. It's a product of an awful understanding of consciousness. So no, we will never plug our brains to a virtual heaven, but does that mean that something similar to the matrix is not possible? Actually it is already possible in a rudimental way. Whenever we dream lucidly we create a virtual reality. Dreams can be considered a primordial way of creating a virtual reality. But it's important to keep in mind the difference between dream and perception. They are 2 different states of the mind, you can't mistake one for the other.


All empirical and instrumental interactions a brain has with it's surroundings is conducted through neuron-firing. Your eyes detect light reflected off a coffee cup and signals are sent to your visual-cortex with neural signals. Internally you reconstruct a three dimensional model of the coffee cup from the stereoscopical two-dimensional picture. You decide to move your hand to grasp the coffee cup and your motor-cortex sens out the appropriate neural signals to your muscles.

It's all neuron firings.

So yes, in principle there is nothing preventing you from putting a brain in a vat and hooking it's neural inputs and outputs to a sophisicated computer and simulating a universe for it to interact with, preserving all memories.

There is also nothing preventing you from just using a sophisticated MRI-scanner to read all the configurations of all the neurons and memory-enzymes and neurotransmitter concentrations in the brain and then simulate those directly in high enough fidelity to preserve all the information and thereby the person.

A person is the sum of their parts, i.e. the information stored in the brain and the continuous computational process the brain carries out.

  • I don't see how one can simply claim that "a person is [nothing more than] the sum of their parts. It's like ignoring half of what's ever been said and written about humankind. Probably more. I'm not disagreeing here, I just don't see what's left to do if we can say that, unsupported by any facts, by any theory, by any name. What are your arguments for people who actually disagree with your theory?
    – iphigenie
    Jan 22 '13 at 11:25
  • I can possibly agree that it's theoretically possible to artificially keep a brain alive and stimulated; in effect there's really no difference between that and taking a hallucigenic pill like LSD. But it's a huge leap from that to your last two statements. To assume that you can use a MRI scanner to do such a thing, you need to subscribe to physicalism - and not everyone does, and even if you do, I suspect quantum effects are likely to kick in, mainly because nature is more subtle than people give her credit for. As an example, Geckos were thought to be able to run up and down walls due to Jan 22 '13 at 18:48
  • some gluey like secretion on their feet, this turned out not to be true - they utilsed sub-molecular forces. Finally, no-one is the sum of your parts. Try deducing who you are from your DNA. Jan 22 '13 at 18:50
  • @iphigenie I am not in any way belittling the power of the human brain. I am just saying that the power of the human brain is the power of the human brain, nothing additional. The function of the brain is what makes the person, no additional things are neccesary to make a person. No soul, no "real-ness." Only neuron activity. And there is nothing that prevents computers from simulating neurons. Jan 27 '13 at 17:07
  • @MoziburUllah I did not mean a literal MRI. I meant a super-sophisticated-hypothetical-brain-scanner-we-are-not-yet-in-possession-of. It is also physically impossible to deduce any person from their DNA only. You need their personal experiences too. Also, I am not subscribing to physicalism ("there is only physics") I am subscribing to reductionist realism ("there is physics, maths and physics behaving like math, and everything you know to be true is probably true in non-trivial ways, but ultimately a thing inside your brain"). Jan 27 '13 at 17:12

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