Faster Than Light ep02: Tachyons and Time Travel


Today our focus is on Tachyons, a hypothetical
particle that travels faster than light and has an imaginary mass, and even more so on
time travel, which we need to talk about before we get to some of the other subjects like
wormholes. Last time we talked about the basics of Special
Relativity when it came to making time slow down and we cleared up some confusion people
often have with that subject before talking about Quantum Entanglement.
Today we’ll be expanding on those notions a bit so if you haven’t already watched
the first episode you should do that now unless you have a pretty solid grasp of Special Relativity
already. Which is to say if you’ve seen these two
equations before and used it several times you’re good, otherwise not. Now these equations
didn’t show up last time but ought to look fairly familiar. Last time we talked about
distance and time contracting, today we are more interested in mass.
So we’ve three new quick concepts to look at. Rest mass, the Lorentz Factor, symbolized
by the lowercase Greek Gamma, and the Capital Greek Beta. That last one is the easiest,
when we are dealing with truly relativistic velocities we always talk in terms of the
speed of light. Something is going .9 c, or .5 c, and we just use Beta for that, if Beta
equals .5 then you are going at half the speed of light. Saves time and makes for a smaller
equation. The Lorentz Factor, Gamma is much the same
thing, if you calculate gamma for any given speed you can just multiply or divide it by
your proper length or time to find out how much time is dilated or length is contracted.
You can also multiply it by rest mass to figure out what the relativistic mass is.
Now rest mass is a simple concept but has some tricky aspects. It is literally how much
mass something has when measured when it isn’t moving, when it is at rest. But we usually
don’t use non-rest mass, relativistic mass, in favor of just keeping that invariant and
thinking in terms of the objects total energy. So we use energy, momentum, and rest mass
energy together a lot. This makes gamma way more convenient but also
means we often like to talk in terms of gamma, not Beta, since its effects are more intuitively
obvious. I mentioned last time that an object moving at 87% of light speed, or Beta=.87,
would appear to be scrunched up in the direction of motion by half and have its clock running
at half speed, and that one doing 97% would be condensed down to a quarter and have time
running at a quarter speed. That’s the case for gamma equal 2 and for respectively, and
that’s easier to think with. Here on this table I have selected gammas by their beta
value. And as gamma rises time slows down more and more and the energy you need to get
to that speed rises sharply. As you can see you never quite reach Beta
=1, or light speed, until gamma is infinite, meaning anything with rest mass needs infinite
energy to get to light speed. And you’d need more than infinity, something of a nonsensical
concept, to accelerate anything with rest mass over light speed. Of course if anything
started off with that speed to begin with, like our tachyons, they wouldn’t need infinite
energy to get there, same as photons don’t need infinite energy to be at the speed of
light since they have no rest mass. This is where imaginary mass comes into play.
If you pump in a value for Beta of more than 1, say 1.41, then Beta Squared equals 2 and
1-2=-1. Now we have a problem again because there’s no real solutions to the square
root of a negative number. That’s why Rene Descartes, best known for
“I think therefore I am”, created what we call an imaginary number, i, which when
multiplied by itself equals -1. Hopefully you’re already familiar with that because
I don’t want to spend time discussing it, but odds are good you don’t know that the
reciprocal of i is –i, so when we get 1 over i here we can just replace it with –i,
giving us a negative imaginary gamma and a negative imaginary mass.
We don’t really care about that negative and don’t usually mention it to avoid confusing
with negative mass, which we’ll be talking about a lot when we get to the Alcubierre
Warp Drive and stable Wormholes, so we usually just say imaginary mass.
Now imaginary numbers bug people, especially in terms of physics which unlike math is only
supposed to deal with reality, but imaginary numbers come up a lot in physics, and even
trigonometry features them though we usually hide it. And imaginary mass isn’t limited
to tachyons, this hypothetical particle now in disfavor, we use it for tachyonic fields
for the Higgs Boson too. We also use imaginary time in Cosmology.
Conceptually the easiest way to explain the tachyon running back in time is just to think
how as time slows down as you approach the speed of light, freezing at the speed of light,
that it just starts running backwards above the speed of light.
Now Tachyons are a whole class of particles, anything which might move faster than light.
We don’t assume it to be a single particle like an electron. In this context we also
have the luxon, any massless particle like the photon or gluon that travels at the speed
of light and experiences no internal time, and the Bradyon or Tardyon. Tachyon comes
from the Greek word for rapid, and Tardy is Latin for slow, whereas Brady is Greek for
slow so Bradyon is probably more consistent but neither gets used much. But a Bradyon,
or Tardyon, would be any normal matter with a rest mass.
The application of the Tachyon is obvious. If you can generate them then you can send
them back to a given place and time to be received. Time travel telephone or radio,
and presumably something you could use to send people back in time too, or homicidal
androids. The tachyon was first proposed in the early
sixties, though it was known as a metaparticle at the time and soon renamed. It made a couple
appearances in science fiction novels in the seventies but its first use I know of in TV
or film was in Doctor Who, during the episode the Leisure Hive whose last installment amusingly
was on the day I was born. That combined with the obvious time travel application of a particle
that moves back in time is why the intro for this series has the doctor who theme. It’s
going to come up a lot in the series because there are not many situations where you can
travel faster than light without traveling back in time.
I wanted to discuss these issue of Temporal Paradoxes back in episode 1 but I didn’t
want to run overly long and Time Travel, pardon the pun, is a time consuming subject. Time
travel and its paradoxes tend to give people headaches, probably because its use in fiction
necessitates it not quite making sense, but today we’ll be trying to explain how it
works minus the headache. That pretty much ends our interest in the Tachyons though,
they are simply a vehicle to time travel and their hypothetical status means we have no
proof they exist, they might not exist, and we have no idea how we’d ever detect them
if they did. So let’s move on to time travel. Fortunately it’s also a topic you are probably
already acquainted with. The two classic examples, in terms of paradox, are known as the Grandfather
Paradox and the Casual Loop. There are some other ones, but they usually represent the
same thing under a different name or minor thematic rather than functional variation.
The Grandfather Paradox is when you go back in time and keep your grandparents from every
meeting, this causing you to never be born, thus preventing you from ever traveling back
in time to prevent that meeting, erasing the problem. In terms of alternate timelines or
Many Worlds theory this can have different effects we’ll come back to in a bit.
The Casual Loop is the other angle on the paradox. Casual Loops, as the name implies,
are where effect precedes the cause, or has a sort of chicken and egg thing going on.
An event causes another event which in turn causes the original one. A loop of cause and
effect, or a causal loop. The evil computer intelligence finds itself
losing a war with the human resistance and notes that the leader of the resistance seems
to be an abnormally larger factor in the loss and deduces that if he had never existed the
resistance would never have existed either or been far weaker. So he sends a murderous
robot back in time to prevent the birth of said resistance leader by killing his mom.
The resistance leader sends his own guy back in time to protect his mom who then ends up
being his father and forewarns the mother of a lot of the problems, so she ends up raising
a kid who really is an abnormally skilled resistance leader, leading the machine overlord
to correctly deduce that removing him from play before the game even got started would
be a smart move. In the grandfather paradox you never travel
back in time to kill Hitler because having killed him you erase your motivation to travel
back in time and do it again. In the casual loop paradox, you get this chicken and egg
aspect, your time travel ends up causing your reason for time travel.
Skynet decides he has to eliminate John Connor in the past, not now, because he made the
resistance so much more dangerous, but the reason for that was because the attempted
assassination resulted in him having the foreknowledge and training to be dangerous. This is why
casual loops are also called Retrocausality, pulling yourself up by your own bootstraps,
or Self-Fulfilling Prophecies. Now we need to talk about Quantum. In Quantum
Physics there are numerous interpretations of seeming Quantum Randomness. The two you’re
most familiar with are Copenhagen and Many Worlds. We don’t really have a way to test
which is true, if any, because they are all designed to match what evidence we do have.
Copenhagen looks at Schrodinger’s Cat and says the critter is simultaneously alive and
dead until you look. I prefer to think of it as coin that’s spinning,
simultaneously heads and tails, until you grab it, since I like cats. Plus I think a
spinning coin better represents the concept of an undetermined state.
In Many Worlds you don’t know the result until you observe it but it assumes the event
actually spawned two different realities, one alive, one dead, or one heads, one tails.
The result is already determined, you can’t predict which universe you’re in but the
contents of the box or the coin flip are already resolved you just need to check them.
Time Travel is mostly not a problem in Many Worlds. If you jump back in time you just
spawn a new timeline. In fact there ought to be a version of reality right now where
by sheer quantum randomness various atoms in your front lawn have coalesced into a blue
police box some gentleman just stepped out of, complete with detailed but fake memories
of time travel. That’s the irritating thing about quantum,
since any given atom has a finite chance to change into another atom, there is a much
smaller chance of two of them doing it at about the same time and place, and a far smaller
but still finite chance of that happening in many atoms to produce some macroscopic
and weird thing out of nowhere like and individually wrapped candy bar or a person possessing an
entirely randomly created memory. So in many worlds there’s already a reality in which
someone has appeared genuinely thinking they’re a time traveler even though they didn’t
even exist till five seconds ago. This concept is merely an extension of the
notion of a Boltzmann Brain, in a truly random system any state that can exist will eventually
exist, and that would include a brain, complete with everything it needs to keep surviving,
like a body, assembling itself randomly, and that can also include a fake memory, leading
that entity and other people to assume they existed before, a concept we’ll look at
from a different angle when we discuss the Simulation Hypothesis.
But real time travel is nominally viable in Many Worlds anyway, since you wouldn’t even
risk a paradox so long as you were jumping to a time, ahead or behind, in a reality that
was not your own. And it need differ by nothing more than that a single random uranium atom
in the core of the planet that did decay into thorium and Helium five seconds ago in our
reality did not do so in the one you want to jump ahead in time into.
Or a version of the past where an atom of uranium still around now had previously decayed
as Julies Caesar was born, and events are otherwise effectively identical. It’s not
your past or future you are messing with so no paradox is created by your actions.
You need not even necessarily be moving in time anyway, as a parallel reality might simply
have time running there a bit slower or faster so you are simply stepping into a place that
is otherwise identical but a bit further ahead or behind your own time. In many worlds it’s
kind of debatable if going to those other worlds is really the same as time travel or
not, but from a practical standpoint it is. Of course you could still setup a casual loop
in this setup too, though it might be better to think of it as a wave. You get your hands
on a time machine, or reality jumping machine, and wait till the next news report of some
big gold strike on relatively cheap land or some other event less random than the lottery,
like a new tech patent, and jump a bit back in time into a reality where a copy of you
exists waiting for such data too, hand it off to him and he takes off, leaving you there
to assimilate into a near-identical circumstance but now very rich due to your knowledge.
He arrives in the next carbon copy and cuts the same deal with your other quantum clone
and rinse and repeat until eventually some difference exists that breaks the chain and
the wave crashes to an end. This isn’t a casual loop in that chicken and egg sense
since you had a definite starting and stopping point.
Now the Copenhagen Interpretation, that our cat or coin is in two states at once until
observed, doesn’t actually prohibit alternate timelines or other realities, it simply has
no need for them. There’s tons of different ways you can have places besides our own Universe
after all, and some of our other FTL concepts for instance would involve popping into a
parallel Universe, meaning one that has bits and pieces corresponding to our own, that
was smaller than our own or had a higher speed of light and just zipping through there until
you reached that point of congruity and popping back into our own Universe.
But again in Copenhagen there’s no need for these alternate realities, and we often
assume there is just a single timeline. After all an issue with Many Worlds, an incorrect
one but a common concern, is that these branching new realities are all new universes forming
from nothing and breaking energy conservation, or getting you something from nothing.
Which considering our own universe is assumed to have violated that in the first place shouldn’t
be a big concern but normally in many worlds, or in some variations of it, the assumption
is these alternate universes already existed and always have. Think of it as alternate
pasts, not just alternate futures. More than one state of affairs can lead to
an identical final result, a concept that relates to our next concept, and would still
apply even though it assumes there are no alternate timelines.
In the context of Copenhagen Interpretation, with no alternate timelines or realities,
or at least where if they do exist they are inaccessible, we have something called the
Novikov Self-Consistency Principle. Igor Novikov, who came up with the Novikov self-consistency
principle of time travel, argued temporal paradoxes weren’t possible. He closes out
paradoxes in time travel, which are permitted in some solutions of the Einstein Field Equation
for General Relativity, by asserting any event that would give rise to a paradox or change
the past in anyway must have a probability of zero.
This doesn’t ban time travel in and of itself though. It simply is arguing that any time
travel has to result in no paradox or it would be infinitely improbable to occur. Novikov
is arguing that regardless of whether or not time travel is possible, you will not be able
to do anything that causes a paradox. In a conceptual sense, don’t think of this
as some sort of Time guardian who pops out and stops you, but rather that the moment
you take a paradoxical route things would reset to a scenario where you hadn’t taken
it yet and keep doing it until you picked a path that didn’t cause that.
Since in Copenhagen there is always a chance one of the random quantum events will spiral
itself up to the macroscopic level one will eventually occur that results in a non-paradoxical
action. There’s no deletion, our coin that can normally
be heads or tails will simply never land on heads if it doing so would cause a paradox.
You would not remember these resets of course, they will have never happened for the same
reason that once you open Schrodinger’s box or catch the coin, the observed reality
erases the alternate possibility, and as we discussed with Quantum Entanglement, that
erasure is not constrained by the speed of light nor does it even seem to care if it
has to reach back in time to fix it. Again this isn’t implying anything is selecting
that solution that counters the possible paradox, there would be many that did, and many that
didn’t, and one would happen same as a drop of water falling from the sky will eventually
take a path leading to the ocean, whether it does so by falling right into the ocean,
or on your roof and following drainage ditches and waterways to the ocean, or even falling
on a desert and evaporating. The Self-Consistency Principle tends to bug
people a bit as confusing since it sort of seems like a tautology. Paradoxes are impossible
because paradoxes are impossible, but the difference is that it’s asserting the laws
of physics can’t be chucked out the window by time travel. There’s a comment on this
that this principle seems to permit any type of action can be done through time travel
except killing yourself, since you obviously can’t travel back in time if you’re dead.
I’d say even that doesn’t work though, and something will happen to resurrect you,
like one of those freak quantum events I mentioned earlier where a blue police box and guy with
fake memories of time travel is spontaneously spewed out by quantum randomness. Or someone
discovers cloning and mind uploading, something we’ll be talking about in the future.
Again it’s not that something is stopping specific actions, it’s just that all your
possible state and actions will only be non-zero probabilities when they won’t cause a paradox.
Now Novikov’s views are hardly considered canon, however it comes up a lot in time travel
talk so I wanted to discuss it. Same reasoning as the Tachyon, although in the tachyon’s
case, while it has fallen a bit out of favor in science fiction it has seen a recent in
resurgence in all sorts of pseudoscience especially for methods of immortality, and again we’ll
be looking at that subject ourselves soon, though we will be mostly focusing on plausible
science. Next time in this series we’ll be looking
at the Alcubierre Warp Drive, taking our first dip into how general relativity allows us
to warp spacetime, and another type of exotic matter, particles and fields possessing negative
mass or energy. From there we will move on to wormholes, which rely on many of those
same general relativity concepts and negative mass as well.
I haven’t decided on an exact order to the next few videos since I want to redo the old
Dyson Dilemma video without having to interrupt our regular schedule, but subjects we’ll
be looking at in the near future in no particular order will be a return to the Habitable Planets
Series for a look at Double Planets, a return to Megastructures series for a quick look
at Hoopworlds, neither of which are going to require very long videos so will probably
be sooner than later. We’ll also be taking a deep look at the
Simulation Hypothesis, the concept that we might all be living in a giant simulated Universe,
and some of the implications that would have in regard to the Fermi Paradox. As well as
an introduction to the concept of transhumanism and biological immortality and especially
the latter’s implications to the Fermi Paradox. If we get a chance we’ll look into the Carter
Doomsday Argument and its own implication for the Fermi Paradox, and as you might guess
this jump back into the Fermi Paradox is a major motivation for finally redoing the Dyson
Dilemma, and if I get a chance the Fermi Paradox Solutions video as well. So a busy next couple
months, assuming I can hold to the current weekly schedule.
If you want alerts when new videos come out, subscribe to the channel. And if you enjoyed
this video make sure to like it and share it around for others.
In the meantime, try out some of these other videos, and as always comments and questions
are welcome below. Thanks for watching and we’ll see you next
time.

100 thoughts on “Faster Than Light ep02: Tachyons and Time Travel”

  1. Tachyons have to be quantas of the fabric of spacetime fabric.Only at the moment of the Big Bang( and maybe even now) Is there mathematics to prove something traveled faster than light.

  2. I think I know why mankind will never discover time travel… Wouldnt the people who have discovered time travel in the future travel to our present and give us their technology already? This proposes two reasons: Mankind will never discover time travel, and we are suck in the present. Or, more pessimistically, mankind is destined to go extinct, because if we do thrive indefinitely, we are bound to discover time travel.

  3. Hi Isaac another great video thank you and forgive me if I'm asking a silly question but at the end of the video when you were saying that we couldn't use the second version of transmitting information by transmitting or not transmitting once every second because we wouldn't know when to look for when the person has flipped the coin could it be possible, for example for one group to leave Earth and travel to a distance place but before they leave they tell their colleagues that star"a" say a variable star with a cycle of 1 month and we agreed when to start and stop a message and this star is in-between us say 10 light years. Then even though it is 20 light years between us the descendents of these 2 groups as long as the star stayed in the same cycle they would know when to start and stop a message and since the light has taken 10 years to reach both groups who 30 light years away from each other.
    Forgive my ignorance I'm only a curious layman.
    I'd like to add I for one would welcome the addition of some longer videos.
    Thanks.

  4. Yep, I'm liking it. I'm going to screenshot that cat-carrier and send it to my GF, who seems to be in training to become her neighborhood's crazy cat lady.

  5. This was even easier to calculate since I knew that space and time are dependent on each other; therefore, both time holds space in itself as also space holds time. From these results, however, my acceptance has arisen that through the transformation and lowering of the speed of light by the half-life, also space and the chronons change themselves, according to which, then, normal space would have to change itself to hyperspace and the chronons would have to change themselves to tachyons, which continue to exist in hyperspace as the smallest units of time at their own, old speed, according to which the oldest tachyons would, therefore, have to have a speed of 44,069,497.5 kilometers per second in their own hyperspace. It also became clear to me that each dwindling away of a half-life creates its own hyperspace; thus, already seven different hyperspaces (7 half-lives = 7 X 6,347,755,102,040 = 44.434 X 10^12 years) would have to exist in our universe.
    Furthermore, it also became clear to me that time travels into the past or future can only be associated with this fact, because somehow, the traveling object must be manipulated in such a way that the flow of chronons is steered. So for example, if tachyons with a speed of light higher than ours and present in a hyperspace or normal space would be stored around a traveling object, then it would be hurled into the past, while a flow of chronons below our current speed of light must have a journey into the future as a consequence. This has become clear to me, but the HOW, that has remained a riddle to me. It is now also clear to me that the chronons can only stay and move in normal space, while the tachyons only move in a hyperspace. This, then, along with many other things that have become perceptible to me, about which I would still like to say nothing today, however, because I’m not yet sure of the results. Ah yes, what could still be said: According to my calculations, after the end of the next half-life, our light constant would have to be 172,146.45 kilometers per second. – Billy Meier

  6. https://theyflyblog.com/2017/11/07/dr-cornish-billy-meier-revealed-it-30-years-ago/

    November 7, 2017 at 8:14 pm
    I find this topic so intriguing.
    Also, figuring out how to manipulate tachyons and chronons will enable us to time travel. If we weren’t so bent on destroying each other and the planet, maybe we could actually get busy being the explorers we were meant to be.

    For the whole explanation, see Contact 119.
    Billy MEIER
    This was even easier to calculate since I knew that space and time are dependent on each other; therefore, both time holds space in itself as also space holds time. From these results, however, my acceptance has arisen that through the transformation and lowering of the speed of light by the half-life, also space and the chronons change themselves, according to which, then, normal space would have to change itself to hyperspace and the chronons would have to change themselves to tachyons, which continue to exist in hyperspace as the smallest units of time at their own, old speed, according to which the oldest tachyons would, therefore, have to have a speed of 44,069,497.5 kilometers per second in their own hyperspace. It also became clear to me that each dwindling away of a half-life creates its own hyperspace; thus, already seven different hyperspaces (7 half-lives = 7 X 6,347,755,102,040 = 44.434 X 10^12 years) would have to exist in our universe.
    Furthermore, it also became clear to me that time travels into the past or future can only be associated with this fact, because somehow, the traveling object must be manipulated in such a way that the flow of chronons is steered. So for example, if tachyons with a speed of light higher than ours and present in a hyperspace or normal space would be stored around a traveling object, then it would be hurled into the past, while a flow of chronons below our current speed of light must have a journey into the future as a consequence. This has become clear to me, but the HOW, that has remained a riddle to me. It is now also clear to me that the chronons can only stay and move in normal space, while the tachyons only move in a hyperspace. This, then, along with many other things that have become perceptible to me, about which I would still like to say nothing today, however, because I’m not yet sure of the results. Ah yes, what could still be said: According to my calculations, after the end of the next half-life, our light constant would have to be 172,146.45 kilometers per second. Now to these things, the big question: To what extent are my calculations and findings right?
    Semjase:
    You are marvelous, simply marvelous.

  7. DOCTOR WHO "The Leisure Hive" totally forgot about that one my friend.👍👍👍👍👍👍👍👍👍👍👍👍👌❤❤❤❤

  8. why do you got to complicate things with equations that mean nothing . you take a car for instance you want it to go faster you just spin the wheels faster . well flying saucers are no different you want it to go faster you spin it faster . figure out the algebra 48 mile diameter flying saucer spinning at 70,000 RPM

  9. Circular reasoning works because.. that hurt to look at and I'm glad it no longer on my screen forcing me to read the same 4 words repeatedly lol

  10. 7:39 Surely Skynet is an "it", not a "he"?
    Nit-picking, I know. I am suitably ashamed (as Isaac should be, with his "casual loops"… oops there I go again!). Good vid, but I'm glad he doesn't do them so short nowadays.

  11. The future draws you. Like a cartoon but with a continually changing choice of timelines. Spider-Man knows but has only two dimensions. Two dimensional causality is different. Yet he had an impact. Impacts require energy, specifically directed energy not just back ground radiation. What is Spider-Man?

  12. Thanks for coming, Isaac, if The Tachyons can't prove & don't exist, my only sugg. is just a good issue of mine, which gives me no idea at all, if I can contradict your good occupation, as your own expert at being w. your good right to call me, 0056 96 505 67 01, Stgo., Chile, also a good idea that your lawyer be there, side by side w., whoever you want & ARE, so I can find out etc., 'J.A.,' The Danish Law, My Semi-ac. Wendy,

  13. The problem I see with the Boltzmann Brain (The forces behind it) is that the concept behind it disproves all science, not all known science, ALL science, as it basically says any and all results that can, will, and have happened were all purely coincidence,
    ultimately disregarding all progress to this point in understanding.

  14. 0:46 "unless you have a pretty solid grasp on special relativity" yes, i watch rick and morty sometimes 😎 (obvious /s)

  15. "The Self-Consistency Principle tends to bug people a bit …
    … something will happen to resurrect you, like one of those freak quantum events I mentioned earlier where a blue police box and a guy with fake memories of time is spontaneous spewed out by quantuum randomness. "

    No wonder it bugs people. It's completely silly.

    The concept that time travel is possible, but the universe guards your actions against paradoxes seems like epic nonsense.

    You can travel back and wreak havoc, murder anyone, but if you attempt to murder your parents, or yourself as child, your gun stops working, knives won't cut, random characters spring into existence to stop you, etc…

    IMO that is nearly as logically bad as the paradox it claims to avoid.

    It seems a lot more likely that traveling back in time, is just impossible. The past is simply that: the irrevocable past. Then you don't need absurdities to rescue you from time travel paradoxes.

  16. Regarding the self consistency principal: I'm just wondering what the real world effect that would have on someone's mind who was, for instance, actively trying to violate it. Lets say that I figured out a way to time travel, so I hook up a timer to the time machine for 5 minutes so that when it goes off it will start the time machine and send me back in time 5 minutes, and I then go sit down in the time machine.

    5 min later the timer goes off, I go back in time 5 min and am now in my lab and looking at the timer and the time machine with me sitting in it. Lets say at that moment I choose to walk over and unplug the timer, thereby preventing me from traveling back in time and creating a paradox.

    How would the self consistency principal stop me? Would it do something to my mind that would prevent me from unplugging the timer? How would I mentally justify that afterwards, since the entire point of my doing the experiment was to unplug the timer and create a paradox? Would this principal really go so far as to violate free will to preserve self consistency?

  17. tachyon is the particle of time with gravity some how like spacetime. for the smarter ppl should know the reference to this.

  18. This means, if you travel back in time and kill your "can kill your father ", it implies that … Your biological father was the mailman. Then, there is no paradox. But if you kill the mailman, then your biological father was your legal father. And if you try to kill both, you will fail at it.

    Interesting solution to proof there is no paradox.

  19. I only have one significant objection to Novikov's Principle: Principles are not reliable in asserting what is "possible". A number of principles are currently in doubt due to the AMPS firewall conjecture, and from some of what I have been reading, the LIGO data from black hole mergers suggests these may be a thing. This suggests that under extreme circumstances we cannot be sure these principles will hold. Is time travel bloody unlikely? Yes. Is it practically impossible? Also probably. But the more we learn, the more dangerous we find these assumptions to be.

  20. You need to edit in a slight change to this video roughly 14 minutes in you mention that “no time guardian is going to pop out and stop you from causing a paradox” that is literally the plot from TimeCop and so you should put in a picture of Mullet haired Jean Claude van Damme… i mean if dr Who gets one Guile should too. Keep up the great work, youtube has learned i only come here to watch you and Steven Colbert’s monologues… and I haven’t yet watched his yet & I’ve watched 2 of yours!

  21. Interesting description of alternate (multiverse) realities, somewhat similar premise behind the Sci-Fi TV series in the 1990s, "Sliders", really unique TV portrayal popularizing the concept. Would be fascinating to bring back a similar series…

  22. Isaac,
    Could you please tell me the name of the song/track you use in your video intro (where the ball-like thing is traveling through the wormhole) as well as the one that starts at around 0:28?

    Thanks so much, and love your vids! Keep it up!

  23. If you go faster than speed of light, nothing will happen as long as you in pure space, space doest move at all or accelerate, space is infinite and you can go 10x faster than speed of light and you won't feel a single thing because there is nothing to make u feel weird unless you were forced to go at speed of light then you will die but if you start out with just speed of light, you would be fine.

  24. Doctor Who? Never heard of him… until I watched this video and thought about it for a second, all at once I have a number of memories watching this show in the 70's when I was a young boy. Thanks for the time warp!

  25. When the subject of "massless" particles comes up, it usually means that a particle has no Rest Mass.

  26. One great example of the casual loop would be the movie Somewhere in Time (1980). It's pretty much the chick flick version of The Terminator 🙂

  27. You can't change the past through time travel because everything you will do in the past has already happened and likely contributed to the past as it is so the time line is fixed. One possible consequence is the future is fixed as well since the present is the future's past.

  28. did you ever see prince of darkness ca. 1987? convoluted plot involving tachyons and idk, i guess demons. dumb but really cool cause alice cooper had a bit part and did the soundtrack

  29. I do not see how faster then light travel means time travel (into the past i assume). Lets take an example. I can travel 1 light year per minute. I go to Alpha Centauri. Takes me 4 minutes and i immediately turn around taking 4 more minutes. When I get home it is 8 minutes after i left. no time travel. Say i can get to A C in a millisecond, when i get home it is 2 milliseconds after i left, again no time travel. On a space time diagram the space travel is still from the past to the future, sure, sloped past the 45 degree line, but never going DOWN.

  30. MEGA LOL. Didn't know these were called imaginary numbers in English. I learnt about them as a high school senior, in fact did some calculations with them which I at the time considered pretty mean (third degree equoations, basic functional analysys etc.) . Fact is, their name from my native language literally translates to complex numbers, which sounds kind of the opposite to the silly name given in English. It's quite a handy concept tho.

  31. I watch your videos fairly often. I find them to be very easy to watch and information is given at, in my opinion, an optimal speed for comprehension. It appears that a lot of time, consideration and personal passion play a very large role in the way the videos are constructed and explained. I have always had interests involving higher mathematics, physics and to put it simply, the mechanics of the very large scale reality, and the the very small enticing realm of particles or "fabrics" that are at work in ways we may never truly be able to even theorize. So, thank you sir, for your time and your passion. I was fairly seriously disabled a few years ago, and before that i had very little time for things like television or YouTube. Your videos are much more than extremely well explained, making them very educational, but they are also fun to watch, and they never fail to unleash my mind to freely explore the complexity and awe of all

  32. Say you invent a time mashing and you have designed it to go both to the past and to the future, You takes this for a testdrive going to the future you observe yourself in that future, does this imply your return trip will succeed?

  33. Time travel happens every second of every day, week month year century and millennium! The way to travel further into the future, your time has to be slower than elsewhere. This could be done by traveling at relativistic speeds or orbit a very very very very massive object, such as a black hole. Neither can be done with current technology. Going back to the past would be even harder! The only theoretical method of backwards time travel is by using a wormhole, wormholes are thought to usually be too small and unstable to be traversed. You would probably need exotic matter and energy to make wormholes useable. Traveling to the past would likely change it, possibly to the point where you weren't born in order to go back in time to begin with! Unless you travelled to another universe, that is!

  34. Time doesn't work that way. Time is just just a man-made concept to to calculate movement of molecules through space.
    To time travel you would have to reverse all of molecules in time travel.
    Time travel makes for a good sci-fi story. and that's about it.

  35. Your problem of time paradox is only because of a false conception of "me" (identity).
    If you travel back in 1999 to look at your own birth for instance. Who are you going to be? The 19 yo you are today, looking at a new born baby? Or the now born baby being looked at?
    You're gonna be the 19yo time traveller. The baby is not you; if it were you, you would see from his eyes at the time! Go kill his grand father if you like, it won't cause you to stop exist. It's not a question of "new timelines", "alternate pasts", or such "ad hoc" inventions at all. No need for "zero probability" neither.

    Really it's hard to me to even UNDERSTAND how you can even find a paradox in these time travels, as if there were any paradox, then the paradox wouldn't be at the moment where you kill the grand-father before he fucked the grand-mother, but at the very moment you cross or overtake the "self" you. When you travel in past direction you start to exist twice. Here is the paradox : you at this time start to exist two times but you feel only one of them, the other is felt as a memory as well as a stranger if he's seen, but not as yourself, otherwise you would see through his eyes! Resolve it here and there could be no other paradox. Who are you really? You're only yourself and that's it. You will never be your past self or your future self, even less the future of your past self! One can only be here and now. Past and future are only memories and interpolations. If you persuade someone that his mother was dead two years before he was born, this "memory" will not kill him even if it's stupidly impossible! So memory CAN be in opposition with reality : it's only memory. That makes no problem. Having existed when young, having had a grand father, and having killed the grand father are all only memories. But fact is you ARE here and now, whatever memories you have. When you travel in the past it stops to be your past it's your present! Your past will only ever be a memory and nothing real/else. And your future an imagination. If you understand you can never be anywhere else than here and now, you won't find any paradoxes. Your past (memories) could be in 2069, your future (projects) in 1855 and your present in 2030 because you time-travel often… No problem. But never ever will you stop being yourself here and now.

    All the time paradoxes can only exist in minds of people failing to understand the nature of the self. And if they were just a little clever, they would understand the paradox is not happening when they kill their grand father, but much earlier when they cross their "past self" without being him. They need to think about that, they need to understand why they feel being their own self and not their other self at this moment, if they understand that, then they won't see any other paradox. I'm really fascinated how so much very smart people could have missed that for so long as it is really so obvious.
    Please note that Einstein's relativity is impossible too in the same minds who have problems with time paradoxes. For the same reason. You don't understand the relativity if you don't understand the self (the subject).

  36. Douglas Adams: "There is no problem in becoming your own father or mother that a broad-minded and well-adjusted family can't cope with."

  37. "I think therefore I am" he says and invents the imaginary number i. That is uncanny, because i is not a real number; which is another way of saying "I think, therefore I am not". Try and understand that!

  38. 1) I apologize in advance, I'm too lazy to read all 357 comments to see if others have already said this
    2) I absolutely love you replacing the living dead cat with a spinning coin!!! That makes a lot more sense!!!

  39. Ok. I am probably going to watch this later but I got here from Google where this video has the title CASUAL LOOP.

    Is that on purpose? Asking on behalf of a friend. Well more like a CAUSAL acquaintance.

  40. The Universe is one gigantic brain, the astral bodies are its components, the great strands are the information carriers, we are simply bacteria and some of us viruses on a single tiny cog in the universal wheel. Black holes are the digestive systems of the universe, all that energy goes back to the Universe through wormhole conduits, allowing for timeless existence. The Universe is electric, the brain is electric. The Universe is not expanding anymore, it is beginning to stabilize due to its limited matter, the expansions that you see are an illusion of the past, the EDGE of the visible universe is 13.8 billion years in the past, the half-way point is 6.9 billion in the past…. where is it actually, at the present? We see the sun as it was 8 minutes ago, we see our closest neighbouring star the way it was 4.2 years ago, for all we know it could have exploded by now and we’d only know it 4 years down the road. Our observations are being skewed by our perspectives. Think about that, for all we know, the Universe May have started to contract, we just won’t be aware of it until we see it , and that takes time because of the speed of causality. Just because something is 13.8 billion light years away it doesn’t mean it’s at least 13.8 billion years old, the space between us is not the same age, some repulsive ancient force may have existed that may have been anti-matter and there’s just more of it as you venture towards the outskirts in every direction and it gets turned into energy by matter and the force disappears over time. This may have already happened and the light from these sources has not had time to reach us, we are only seeing the expansion and the attraction is already in progress. The Center of the universe is always where you are located, all observations are from the past, we cannot see these objects as they exist in the present, the only thing we can do is look into the past and attempt to predict the future based on old observations. It’s like trying to base your awareness on windows into the past but not thinking about what is happening right now. Something 100 light years away is actually something we analyze as it was 100 years ago, the further you go, the less likely that this is still the picture it is actually an exponential improbability.

  41. With the Grandfather Paradox, you go back in time and create a situation which results in you not being able to go back in time in the first place.

    With the Casual Loop Paradox, you’re either going back in time to do something that will result in a situation that already is thereby negating the reason to go back in the first place, or you become responsible for whatever it was that you went back in time to prevent thereby making you stupid for wasting you time and causing the problem (unless that is, you were getting paid to do this, which case you might be an evil genius).

    Likely, until the time that the forces of entropy over come the forces of order, the Universe will find a way to prevent the paradox.

    Unless there is a multiverse. In which case, going back in time and having any effect on anything, will result in an alternate version of events in another time-line/universe. However, the time traveler would of had no effect on his prime universe.

  42. The Outside Threat in the later FH Dune books had a tackyon net they used to look for a ship that was on the run.

  43. So if someone has already invented ftl travel they travelled backwards in time and now live in a different timeline? Space time can twist and stretch, maybe we already have 'travelled' back it's just our present cannot be altered?

  44. My favorite solution to the "grandfather paradox" is the one that states if you go back in time, you can prevent your grandfather from meeting your grandmother. Your existence pre-dates the changes you made, regardless of the fact that you have altered the past. Your past still exists from your perspective, even though it now does not occur. In other words, you exist, and any action you take cannot alter that fact.

  45. Relativistic mass doesnt exist. The problem was with scale and reliance on mathematical models that have no experimental evidence, or weak experimental evidence.

  46. https://www.researchgate.net/publication/334120158_Tachyons_but_Not_Photons_Might_Generate_Conscious_Dreams

  47. My theory about time travel is that you can't change fixed moments in time but known or unobserved moments in time are changeable for example you couldn't stop the Titanic from sinking but you could save the lives of those whos body's were never found basically if something in time is objectively determined to have happened it becomes fixed and can't be changed no matter how hard one trys to intervene but unfixed moments in time can be changed

  48. Relativity means ftl is weird. For example, let us take a device that allows instant transit between two big ring gates according to the reference frame of gate A. If a space ship is traveling at, say, .5 c, simultaneity will be broken, so it is possible that they would see you depart from gate B before you entered gate A. But, if you traveled back, they would see that as taking time and not instant. However, if after they saw you arrive at B but before they saw you leave A, they stopped, then problems would occur

  49. I cant be the only one who thought of this but insofar as the coin is concerned… if there were established rules between the partys holding them governing a few simple signals, you could transmit 01, 10, 11, 00, albeit very slowly.

    Say you need to say 00. Random flip gives 0, random flip gives 1. No good, hence you send no third "flip" as a confirmation signal. Signal time elapses, restart: random flip gives 0 random flip gives 0, good, so a third flip is sent (whose value is meaningless) as a confirmation signal – it would be sent automatically by a machine obviously so it would be keyed in an EXACT amount of time after the second positive flip, showing it to be a confimation signal – all of the "flipping" would be done by a quantum computer after the value needing to be sent was keyed in by the user.

  50. So if you fired a hypothetical tachyon energy beam weapon at someone would you expect the beam to erupt from the target's chest, and fly into the barrel of your weapon since they are moving backwards in time?

  51. I a current vid, you say that you want to inspire authors to write sci fi that you want to read.  The books, "Wasn't Tomorrow Wonderful", "Galactic Time Trap", and one of the later books in the "Rules of Supervillainy" series combine time travel and alternate realities to avoid the Grand Father paradox. As for causal loops, "The Galactic Time Trap" explores this with a concept how to determine if you are in one.

  52. https://theyflyblog.com/2017/11/07/dr-cornish-billy-meier-revealed-it-30-years-ago/ The Tachyon particles do exist and can travel only in hyper space beyond the speed of light. According to Billy Meier Contact Reports over 700 Contact Reports till today with Plejaren ETs civilization. Plejaren ETs civilization use this tachyon particles drive to space technology to travel billions of light years in a fraction of second by entering in hyper space with their flying saucers by collapsing space and time 🛸 and sending the flying saucers 🛸 by tachyon drive particles. More info from Contact Report of Billy Meier with Plejaren ETs civilization here . https://theyflyblog.com/2017/11/07/dr-cornish-billy-meier-revealed-it-30-years-ago/ It’s possible to travel beyond the speed of light by beam drive and with second drive called tachyon drive to travel billions of light years by collapsing time and space in null time and enter in hyperspace travel and send the those tachyon particles in billions of light years in a fraction of second important is to have the anti gravity shield to protect the pilots in space craft or flying saucers 🛸 and to control the time when you are in hyperspace not to get lost in future or past , more informations in Billy Meier Contacts reports with ETs Plejaren. https://theyflyblog.com/2017/11/07/dr-cornish-billy-meier-revealed-it-30-years-ago/
    YOU CAN GO FASTER THAN SPEED OF LIGHT YOU SHOULD STUDY BILLY MEIER CONTACT REPORTS
    November 7, 2017 at 8:14 pm
    I find this topic so intriguing.
    Also, figuring out how to manipulate tachyons and chronons will enable us to time travel. If we weren’t so bent on destroying each other and the planet, maybe we could actually get busy being the explorers we were meant to be.
    For the whole explanation, see Contact 119.
    Billy MEIER
    This was even easier to calculate since I knew that space and time are dependent on each other; therefore, both time holds space in itself as also space holds time. From these results, however, my acceptance has arisen that through the transformation and lowering of the speed of light by the half-life, also space and the chronons change themselves, according to which, then, normal space would have to change itself to hyperspace and the chronons would have to change themselves to tachyons, which continue to exist in hyperspace as the smallest units of time at their own, old speed, according to which the oldest tachyons would, therefore, have to have a speed of 44,069,497.5 kilometers per second in their own hyperspace. It also became clear to me that each dwindling away of a half-life creates its own hyperspace; thus, already seven different hyperspaces (7 half-lives = 7 X 6,347,755,102,040 = 44.434 X 10^12 years) would have to exist in our universe.
    Furthermore, it also became clear to me that time travels into the past or future can only be associated with this fact, because somehow, the traveling object must be manipulated in such a way that the flow of chronons is steered. So for example, if tachyons with a speed of light higher than ours and present in a hyperspace or normal space would be stored around a traveling object, then it would be hurled into the past, while a flow of chronons below our current speed of light must have a journey into the future as a consequence. This has become clear to me, but the HOW, that has remained a riddle to me. It is now also clear to me that the chronons can only stay and move in normal space, while the tachyons only move in a hyperspace. This, then, along with many other things that have become perceptible to me, about which I would still like to say nothing today, however, because I’m not yet sure of the results. Ah yes, what could still be said: According to my calculations, after the end of the next half-life, our light constant would have to be 172,146.45 kilometers per second. Now to these things, the big question: To what extent are my calculations and findings right?
    Semjase:
    You are marvelous, simply marvelous. https://theyflyblog.com/2017/11/07/dr-cornish-billy-meier-revealed-it-30-years-ago/ From Author Gary Kinder's "Open Letter to the UFO Community"
    David Froning: At the time, Dr. Froning had already spent 25 years as an astronautical engineer at McDonnell Douglas in highly classified military defense and, in 1979, became interested in Billy Meier's accounts of Plejaren starship travel, which mentioned tachyon propulsion. Dr. Froning found Billy Meier's account of tachyon propulsion (which was only beginning to be discussed by a very small and select group of theoretical physicists), and his calculations for above light speed travel to be amazing. In 1983, he was pursuing his Quantum Interstellar Ramjet idea (JBIS vol. 33, no. 7, July 1980; AIAA 81-1533, July1981; IAF-85-492, October, 1985) and plugged in his Quantum Ramjet performance equations, assuming: a given starship density, vacuum energy conversion efficiency (in transforming positrons and electrons within the quantum vacuum into photons), and vacuum energy conversion scales of distance of the order of the Compton wavelength. The resulting vehicle acceleration enabled achievement of almost light speed in about 4.3 hours and deceleration from light speed in about 4.3 hours. Billy Meier said that the elapsed time during the "hyperspace jump" took only several seconds. Thus, trip time between the Plejaren star cluster and Earth with Froning's slower-than-light Quantum Ramjet Drive plus a hypothetical tachyon drive would be 8.6 hours, which was within 20% of the Plejaren trip time reported by Billy Meier. But, while Froning's calculations were based on many arbitrary assumptions, and in no way proved the truthfulness of Billy Meier's account (since it was a theoretical system he was working on, only time will tell as to which are correct) Froning was somewhat startled that his arbitrary flight time computations were within 20% of the flight time mentioned by Billy Meier. Regarding the Billy Meier material, Dr. Froning also publicly stated that, "My colleagues and I may have made breakthroughs in our understanding of possibilities and ways for traveling faster than light from Billy Meier's accounts of his encounters with the Plejarens." FUTUREOFMANKIND.CO.UK ; FIGU.ORG
    THEYFLY.COM ;HAPPY READING 😃🛸✌️👍🛸😃✌️

  53. Rene Descartes invented i? Dufuq, I didn't know he was a famous mathematician, I thought he was just a philosopher. He vivisected his pet dog, just cut it open, since he was that confident that dogs are all philosophical zombies, or NPCs, in modern terminology (look up philosophical zombie). I guess mathematicians tend to be idiosyncratic, but Descartes's idiosyncrasies were what I thought he was effectively famous for in the first place.

  54. Hmm interesting but your talking about to fast like your reading… Nice video but sadly people have repeat watching over and over again

  55. Under many worlds it's not that a virtually infinite number of universes are constantly popping into existence from nothing because there are a virtually infinite number of already existing universes which have could continuously become this one for an instant. Alternate pasts as well as alternate futures. [head explodes!]

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