What does physics tell us about the possibility of
immortality or an afterlife?
First, let’s address the elephant in the room. To the physics community, “afterlife” often implies
“religion” often implies “stupidity.” Bullies
Dawkins have made it very clear that anyone who even suggests the existence
of God or an afterlife is intellectually inferior. Oddly, this assertion directly conflicts with
several arguments based on currently-understood physics (and often made,
ironically, by atheists) that immortality is possible. I’ll discuss below some of these
arguments. Importantly, any physicist
who tells you with certainty that there is no afterlife is not only
mistaken, but is ignorant of the direct logical implications of his/her own
beliefs about physics.
Note: “Afterlife” and “immortality” are not technically
the same. Immortality might be
interpreted as “never dying,” while an afterlife might be interpreted as “consciousness
after one has died.” However, from a
physics standpoint, this is often a distinction without a difference. For example, if mind uploading is possible,
then it can be done before or after a person’s brain is dead.
My close friend (and former MIT debate champion) once made
the following (valid) argument:
Technology (e.g., medicine) is allowing humans
to live longer and longer.
There is some tiny but nonzero probability
0<p<<1 that we will develop the technology to indefinitely postpone
death. For example, imagine that in the
next 50 years we figure out how to make humans live to age 150, and in the following
50 years we figure out how to make humans live to age 200, and so on. Then someone born today could indefinitely
The universe will continue expanding
forever. (Most physicists believe that
the universe has positive
p * ∞ = ∞.
Therefore, the life expectancy of a person born
today is infinite!
The argument applies equally to an afterlife as to
immortality if we simply replace the second statement with “There is some tiny
but nonzero probability 0<p<<1 that we will develop the technology to
reanimate a dead person’s brain.” (After
all, that’s why the quacks at the Brain
Preservation Foundation recommend cryogenic freezing of one’s brain, which
I’m certain is not cheap.) If we
can agree that it is at least physically possible to indefinitely delay
death (or to reanimate a dead brain), then physical immortality/afterlife
cannot be ruled out.
If you can upload your conscious awareness onto a
computer, then you can live forever because a computer can be indefinitely
operated and repaired. Okay, okay, you
still need energy to flow, which will stop when the universe experiences its
death in at least a googol years.
Even still, Michio Kaku in his fascinating book, Parallel
Worlds, points out that conscious awareness would slow down commensurate
with decreased energy transfer so that one’s subjective conscious experience
Again, there’s no difference here between “immortality”
and “afterlife” since the fundamental assumption of mind uploading (and
algorithmic consciousness) is that a conscious state is just software running
on a computer, and that can be done long after one’s death. (It can also be done before one’s
death, which leads to all kinds of ridiculous paradoxes that I discuss in this paper.)
The problem is that I showed in this paper (and this) that consciousness is not
algorithmic, which means it cannot be uploaded to or executed by a computer
(whether digital or quantum). Mind uploading is not physically possible.
Tegmark, proponent of the wacky and unscientific Many Worlds Interpretation
(“MWI”) of quantum mechanics, proposed the notion of quantum
suicide (although really it’s just “quantum death” because it applies independently
of intention) as an empirical test of MWI.
The idea is this:
Stand in front of a “quantum gun” that is
designed so that when the trigger is pulled, whether a bullet actually fires
from the gun (and kills you) depends on the outcome of a quantum mechanics (“QM”)
Universal linearity of QM – i.e., the assumption
of U which I dispute here
– implies that the quantum event entangles with the bullet, which entangles
with you, to produce a Schrodinger’s-Cat-like state involving you in a
superposition of states |dead> and |alive>.
If MWI is correct, then both states actually
occur/exist (albeit in different “worlds” that are exceedingly unlikely to
quantum mechanically interfere).
Since you cannot consciously survive death – a
huge assumption! – then the only state you can consciously observe is the one involving
|alive>, which means that you are guaranteed to “survive” the pull of the
quantum gun trigger.
You can repeat this as many times as you want,
and every time you will be guaranteed to observe the outcome in which you are
The argument is wrong for several reasons that I point
out in the Appendix
of this paper. One problem is that every
chance event is fundamentally (amplification of) a quantum event, which
means that essentially every death-causing event is akin to quantum
suicide/death. But that means that, if
Tegmark’s argument is correct, then nobody
can actually die.
But the main problem is that the argument depends on the unjustified and irrational
assumption of U. If Schrodinger’s Cat and Wigner’s
Friend can’t exist, then the quantum suicide experiment can never get off
The Boltzmann Brain
concept is the notion that, given enough time, every physical state will repeat
itself. Or: due to random quantum
fluctuations, given enough time, every possible physical configuration that can
fluctuate into existence will fluctuate into existence. So, eventually, even trillions of years after
humanity has gone extinct, the conscious state you are experiencing at this
moment will be recreated (and presumably re-experienced) again. And again and again.
Whether such experiences count as immortality or
afterlife makes no difference, because the Boltzmann Brain concept is impossible. I showed in this paper that physical
instantiations of the same conscious state cannot exist at different points in
Tipler’s Physics of Immortality
Tipler is a Christian who was largely ostracized from the academic world
for showing how what is currently understood about physics could support the
notions of a Christian God and afterlife.
His book, The
Physics of Immortality, is interesting but dense. At the risk of oversimplifying his analysis,
I think his fundamental argument is really the Boltzmann Brain in
disguise. He relies heavily on the Bekenstein Bound
(which I discussed here)
and the notion of Eternal
Recurrence to show that consciousness cannot end.
His analysis is wrong for several reasons. First, the Bekenstein Bound assumes the
constancy of the informational
content in a given volume (i.e., that Planck’s constant is constant, which
may be false). Second, and more
importantly, it assumes that a conscious state is just a list of numbers (even
if it’s a huge list) that must be contained within the volume of a brain, and
therefore that consciousness is algorithmic, which I’ve shown is false. If consciousness cannot be reduced to a set
of bits (and/or their algorithmic manipulation), then the number of bits that
can fit in a given volume is irrelevant.
If physical systems are truly reversible, then – at least
according to some – it should be possible in principle to physically reverse a
person’s death (or even some or all of a person’s life). It’s certainly not obvious that constantly
“undoing” someone’s death results in a meaningful kind of immortality. Still, maybe the goal of reversing someone’s
death is to copy their consciousness into another physical system or upload it
to a computer. But I’ve already pointed
out several times that this is impossible.
Either way, the entire argument is moot because physical
reversibility of large systems is a logical contradiction.
What do I actually believe?
First, let me point out the crazy irony of this blog post
so far. I, the crackpot
in God, am trying to explain why several physicists’ arguments for
immortality or afterlife are wrong!
In fact, the only one of the above arguments that I can’t completely
rule out is Postponing Death, even though I regard it as extremely
implausible to postpone death indefinitely.
Having said that, we do not understand
consciousness. No physicist,
neurobiologist, physician, psychologist, computer scientist, philosopher, etc.,
understands consciousness, and anyone who claims to understand it is likely
introducing unstated assumptions. For
example, most scientists who academically discuss consciousness assume that
consciousness is created entirely by the brain, which is why the hackneyed “brain-in-a-vat”
thought experiment – the namesake of this blog – is so pervasive in the literature.
After all, if consciousness is entirely a product of the
brain (or, more generally, on a local region of spacetime that may enclose the
brain), then the above arguments are a lot more tenable. That is, if a conscious state supervenes on a
physical state that is entirely (locally) contained in some volume, then
Tipler’s argument based on the Bekenstein Bound seems to apply; the total
information specifying that conscious state is finite and, as nothing more than
a string of numbers, can be copied and uploaded to a computer; and so forth.
In fact, given so many physical arguments for
immortality, one might even wonder what physical arguments there are against
immortality. There is only one: assume
that consciousness is entirely a product of the (living) brain; then death of
the brain ends consciousness. And if
that assumption is wrong, then there is literally no existing scientific
evidence against immortality or an afterlife.
But that assumption is wrong. Conscious states are not local
and they cannot be copied to different places in spacetime. (Stoica makes a related and fascinating
argument here that mental states
are nonlocal.) If they’re nonlocal, then
they must physically depend on nonlocal (quantum) entanglements among objects
and particles throughout the universe. That
is, what physically specifies my conscious state logically must extend
beyond my brain. There is certainly no
doubt that my brain affects my consciousness, but it cannot be entirely
locally responsible for it. The fact
that events and physical relationships that extend far beyond my brain are at
least partially responsible for my consciousness leads me to surmise that these
conscious-identity-producing physical relationships will persist long after the
atoms in my brain are no longer arranged in their current configuration. This is the beginning of an as-of-yet
undeveloped physical argument for immortality/afterlife.
So, what do I really believe about an afterlife? I won’t mince words. I am certain that my consciousness is
eternal; I am certain that my consciousness awareness will not permanently end
if/when my brain dies. In future posts,
I will give logical and physical arguments to support these assertions, but I
wanted first to devote a blog post to what currently-understood physics implies.