Time travel (209)

1 Name: Anonymous Scientist : 2006-07-20 11:12 ID:6bO6LaVD

Do you think it's possible?

101 Name: Anonymous Layman : 2007-10-22 23:00 ID:VpMuU2/w

With an infinitely powerful telescope and an unending search of the night sky, perhaps one could peek around the corner of a singularity 500 million light years away and see a billion-year old Earth. Just see what it looked like then, of course.

If it were possible to cause changes in the past that affect the present, I'm sure we'd have know about it already due to the swarm of interlopers coming back to give high-fives to us people from the Stupid Ages.

102 Name: Anonymous Scientist : 2007-11-25 08:55 ID:6PACnZ0v

>>101

But what about the possibility that the time machine has to be stationary (a la Ronald Mallett and his "time machine")?

In other words, you don't travel with the time machine like in back to the future, but instead travel TO the time machine at an earlier point in time. This means that it would be impossible to travel back further than when the first time machine existed, because there would be no arrival point.

Meaning, no one from the future can come to this time because a time machine hasn't been invented yet.

(Keep in mind I am basing this off of a documentary I saw a few years ago, so please correct me if I have misrepresented Mr. Mallett's theories).

103 Name: Anonymous Scientist : 2007-11-30 15:57 ID:a4NPZkeb

OK, point on the speed of a tube of ball bearings 10 light second long. It would take approx. 139 hours, assuming the ball bearings are perfectly aligned and made of steel, for the "information" that the first ball bearing moved to reach the last one.

I know the fact it moves at the speed of sound has already been pointed out, I just thought I'd throw a number next to it.

There are two types forces through a median - longitudinal vibrations and transverse vibrations. Since we are compressing the metal bearings, we want longitudinal vibrations. The speed of longitudinal vibrations through steel is about 6000 m/s.

Also, since there seems to have been some misunderstanding...
as long as the ball bearings are all aligned correctly, they behave EXACTLY like a single unit, except for the last one which will pop out.

Interestingly, a cylinder that is infinitely massive would be unable to be compressed, and it seems that the information of a force should be instantaneous through it, right? Not that it would matter, since it could obviously not exist, but still, it's a curious question.

Also, another question. Since light moves at the speed of light (or very, very close to it), from the perspective of the light (if you can imagine such a thing), would the light exist along all of its paths at once, if we ignore any time it hits a medium that slows it down?

104 Name: Anonymous Scientist : 2007-12-02 16:51 ID:TZ2BDyKP

> Interestingly, a cylinder that is infinitely massive would be unable to be compressed, and it seems that the information of a force should be instantaneous through it, right?

You're making the usual mistake here of thinking of a "solid" as something that actually exists. "Solid" is an intuitive shorthand we use for something which is actually very, very different.

Think about what a "solid" actually is: It's a bunch of atoms packed together, sometimes in a crystal lattice. An atom, on the other hand, is a tiny nucleus surrounded by an electron cloud.

What happens when sound is transmitted is that the atoms move, and their electron clouds push up against each other, and repel because they have similar charges. Now you question becomes, what do you mean by "infinitely massive"? Do you have infinitely massive nuclei with normal electron clouds? Do you have an infinite number of nuclei packed into a finite volumes? What happens to the electron clouds then?

And so on. The answer you end up with is that your question is meaningless and unanswerable, because the situation makes no sense physically.

105 Name: Anonymous Scientist : 2007-12-03 00:19 ID:MK0OTpW5

>>104

Now you question becomes, what do you mean by "infinitely massive"? Do you have infinitely massive nuclei with normal electron clouds? Do you have an infinite number of nuclei packed into a finite volumes?
What happens to the electron clouds then?

Quark-gluon plasma.

106 Name: Anonymous Scientist : 2007-12-04 18:38 ID:cTtQmPZW

>>104
Quark star? Isn't that basically "infinitely compressed", such that it is a solid piece of matter, as much as we understand matter to be? A collection of free quarks gathered together to form, essentially, a single particle of a size similar to a neutron star? If so, that material would be, intuitively at least, unable to support shock waves through it.

And though this is somewhat unrelated, isn't the inside of a black hole considered to be infinitely massive and infinitely small by some? I've read that several times, and it seems blatantly wrong, but maybe it is and I'm just not understanding how gravity works.

107 Name: Anonymous Scientist : 2007-12-04 23:15 ID:MK0OTpW5

> isn't the inside of a black hole considered to be infinitely massive and infinitely small by some?

I imagine that's just poetic license taken by some cheap science fiction writer.

108 Name: Anonymous Scientist : 2007-12-05 06:28 ID:tbSEwcZO

>>107
Actually, cheap science books. Not that there is a huge difference...

109 Name: Anonymous Scientist : 2007-12-07 12:10 ID:E4evLiqi

>>106

That would still be entirely finite.

110 Name: Anonymous Scientist : 2007-12-07 23:57 ID:dEIbNI8R

What about 10 dimensions or M theory?

111 Name: Anonymous Scientist : 2007-12-07 23:58 ID:dEIbNI8R

In the year of '39 assembled here the Volunteers
In the days when lands were few
Here the ship sailed out into the blue and sunny morn
The sweetest sight ever seen.
And the night followed day
And the story tellers say
That the score brave souls inside
For many a lonely day sailed across the milky seas
Ne'er looked back, never feared, never cried.
Don't you hear my call though you're many years away
Don't you hear me calling you
Write your letters in the sand
For the day I take your hand
In the land that our grandchildren knew.
In the year of '39 came a ship in from the blue
The volunteers came home that day
And they bring good news of a world so newly born
Though their hearts so heavily weigh
For the earth is old and grey, little darlin' we'll away
But my love this cannot be
For so many years have gone though I'm older but a year
Your mother's eyes from your eyes cry to me.
Don't you hear my call though you're many years away
Don't you hear me calling you
All the letters in the sand cannot heal me like your hand
For my life
Still ahead
Pity Me.

112 Name: Anonymous Scientist : 2007-12-17 05:56 ID:EtkKbyMa

>>103
I recently read somewhere (I don't remember where) that they're toying with the idea of time as a 4th dimension of space. It seems to me to make sense, but in any case, if it is, I don't think I can say yes to "Since light moves at the speed of light (or very, very close to it), from the perspective of the light (if you can imagine such a thing), would the light exist along all of its paths at once, if we ignore any time it hits a medium that slows it down?"

If time were itself a dimension (what could have happened in this universe without it AND the dimensions of space?), I would have to assume that light moves within the dimensions of space (albeit at an incredible rate), according to the laws of time (which is presumably the only truly 'instantaneous' 'thing'). The actual speed time moves at, as opposed to the speeds things move about inside it, is the speed we have to beat to go forwards. Even then, I don't think we could pin-point A time and zap ourselves there. We'd exist in the 3 dimensions of space, going forwards through time quite literally (as one goes forward through time in their day to day lives). Going backwards seems to me, on this basis, impossible.

113 Name: Anonymous Scientist : 2007-12-17 13:30 ID:Heaven

>>112

Time has been considered a fourth dimension of space-time for a hundred years, soon. Note, however, that that is specifically space-time, not space. The spatial dimensions are different from the time dimension, although they together form a whole.

114 Name: Mahuloq : 2007-12-19 07:37 ID:zQsajZBT

What about the 6 other dimensions of space!
http://revver.com/video/99898/imagining-the-tenth-dimension/

115 Name: Anonymous Scientist : 2007-12-20 01:10 ID:Heaven

>>114

I wouldn't worry about them until the spring theorists actually manage to find some actual experimental evidence.

116 Name: Anonymous Scientist : 2007-12-20 15:56 ID:sW+pmhcT

But if time is a dimension then it should mean we can go back in time, and we have seen that it's highly unlikely. Therefore time can't be a dimension... or that it's a special, one-way dimension?

117 Name: Mahuloq : 2007-12-20 20:44 ID:pDElAak7

I have always thought that to defeat that paradox, when you go "back" in time, you are always just traveling to a parallel dimension, therefore no paradox can occur, fine kill the your mum in that universe, your still there and fine.

118 Name: Anonymous Scientist : 2007-12-21 01:33 ID:Heaven

>>116

It is a dimension, but it is a time-like dimension instead of a space-like one. The Minkowski metric, which describes flat space-time, contains ones for the three space-like dimensions, and a -1 for time: http://mathworld.wolfram.com/MinkowskiMetric.html

There is really no explanation for why our universe can be described with such a metric, but it can, and thus we are stuck with three space-like and one time-like dimension.

119 Name: Anonymous Scientist : 2008-01-04 15:53 ID:9AtRNDu8

>>117

i think it's more like this:

You travel back in time. INSTANTLY, just by appearing in the "past" you have changed that universe irrevocably. A paralell universe is the result, you kill your grandpa, you travel forward in time to the present. Everything seems fine, you don't die because you're actually from a paralell universe, but in that universe you never existed. and life goes on. however, it is not your universe anymore, and you never return to the "present" of your own universe. Nor does the history of your universe become altered.

now that i type it all out, though, it does all seem rather arbitrary - is there any proof of paralell universes?

120 Name: Anonymous Scientist : 2008-01-06 01:04 ID:MK0OTpW5

> is there any proof of paralell universes?

Not yet, and there may never be any.

121 Name: Anonymous Scientist : 2008-01-09 18:39 ID:OxZASRqc

Time-travel is indeed possible. We know the mathematics and methods of how to bend time and space. The only problem is our energy constraints. It would take all the energy of our solar system PLUS that of another to actually travel in time.

122 Name: Anonymous Scientist : 2008-01-09 18:56 ID:sW+pmhcT

>>121
So, two portable black holes? Yup, that's what John Titor was/will be using. Created by CERN's Large Hadron Collider in the near furure. Currently scheduled to begin operation in May 2008.

123 Name: Anonymous Scientist : 2008-01-09 20:46 ID:9AtRNDu8

>>122

that's just plain false. The likelihood of creating a black hole is small, like one a second, when considering the scale of time with particle physics. Next, the holes themselves would be too unstable as such a small scale, meaning they won't last, and FINALLY, even if a black whole were to be created, and be able to stick around long enough to acrete the earth, it would evaporate instantly from (they still technically unproven) hawking radiation. If making black holes to destroy the earth was that easy, some jerkass would have done it by now - or the universe would be CONSTANTLY hurling black holes everywhere.

124 Name: Anonymous Scientist : 2008-01-09 20:47 ID:9AtRNDu8

>>122

Addendum:

how would one use black holes to power something?

125 Name: Anonymous Scientist : 2008-01-10 02:31 ID:sW+pmhcT

>>123
No, those mini black holes created by Man would not destroy the Earth. They probably wouldn't even sink below ground, they would evaporate. The actual danger would come from the evaporation point, with plenty of heat and radiations.
Not all black holes are stellar-size-massive. The braneworld theory predicts the existence of tiny black holes seeded throughout the universe, remnants of the Big Bang. And that thousands of them should exist in our solar system.

126 Name: Anonymous Scientist : 2008-01-11 19:11 ID:9AtRNDu8

>>125

that's what i was trying to say, but i guess i forgot to mention they were really tiny, which is important.

127 Name: Anonymous Scientist : 2008-01-11 20:12 ID:sW+pmhcT

Okay. Next, how much energy does a black hole needs to be? If we look at John Tytor's time machine manual, we see in the "Emergency procedures" section: "Unit self-destruct is pilot controlled. The singularities will automatically evaporate with a compromise in the containment field. A nuclear explosion with the equivalent of 2x megatons will detonate upon singularity evaporation."
So we'll need to get the CERN to cram 20-29 megatons of energy into a singularity. Then we'll be able to time travel.

Oh, and incidentally we'll also need to invent that "containment field" first if we don't want the CERN to vanish. So far it doesn't exist yet... :)

128 Name: Anonymous Scientist : 2008-01-20 19:30 ID:QPZM8lgA

>>Not all black holes are stellar-size-massive. The braneworld theory predicts the existence of tiny black holes seeded throughout the universe, remnants of the Big Bang. And that thousands of them should exist in our solar system.

Holy Magnetic Monopoles, Batman! Wasn't this one of Stephen Hawking's predictions from, like, 1972? And hasn't he abandoned it and moved on?

129 Name: Anonymous Scientist : 2008-01-20 22:22 ID:sW+pmhcT

130 Name: Anonymous Scientist : 2008-01-31 10:14 ID:C7FFjEIl

I already figured out time travel. The problem isn't getting to there. It's getting from here.

131 Name: Doctor : 2008-02-01 01:48 ID:Heaven

ummm...

132 Name: Anonymous Scientist : 2008-02-01 04:56 ID:sW+pmhcT

What's strange in those time-travel stories is that "space" is omitted out of the equation. Time and space are very closely related. A time machine should be able to do space traveling. Even John Titor said that the first problem they had with their time machine is that the machine would re-appear elsewhere, and it puzzled the engineers for a while (it was because the Earth is in motion, while the machine wasn't when operating.) Where are all the space travelers' stories?

133 Name: Anonymous Scientist : 2008-02-01 19:57 ID:idwUBqtg

>>132

This is a very insightful comment,... It sometimes pays of to waste time here

A "straight" time jump of even a few seconds would leave you in cold space. But that's assuming that time travel would somehow use a "fixed" referential. But if there is no such thing, there could still be problems, if time translation warps space translation.

You would add teleportation woes to timetravel headaches.

134 Name: Anonymous Scientist : 2008-02-01 23:39 ID:MK0OTpW5

Not only earth is moving, the system and the galaxy are in motion as well.

135 Name: Anonymous Scientist : 2008-02-02 01:50 ID:Heaven

>>132-134
all motion is relative, only acceleration is relevant in this case. also, it's quite possible that earth's gravitational field might cause the time machine to follow earth.

136 Name: Anonymous Scientist : 2008-02-11 15:02 ID:idwUBqtg

>>135

Well,... Time travel could be seen as a form of acceleration in space-time. In which case some of this acceleration might result in the problems mentioned... Or not.

137 Name: Anonymous Scientist : 2008-02-15 01:16 ID:o/K6QW7l

>>132
That is very interesting. If you think of time like a space dimension, then jumping forward or backward in time faster than the rate we are going now, is like traveling faster than light. So a time machine is an FTL drive. Cool.

And FTL drives are like time machines? And time travel is full of paradox, so it is impossible. Therefore faster than light travel is not possible...so much for humanity taking over the galaxy.

Actually come to think of it again...we can assume that time travel into the past is impossible and so warp drives would be like going forward in time really fast. Fini.

138 Name: Anonymous Scientist : 2008-02-15 14:19 ID:QPZM8lgA

>>warp drives would be like going forward in time really fast. Fini.

lolwut

srsly, ever heard of the theory of relativity?

139 Name: Anonymous Scientist : 2008-02-15 15:00 ID:o/K6QW7l

>>138
Theory of relativity only deals with sub-light travel. I can make up whatever the hell I want to wrt faster than light travel.

Anyway, I don't know what you are talking about. Explain please.

140 Name: Anonymous Scientist : 2008-02-15 20:11 ID:GUxM/xdZ

>>139

It's hard enough to get <i>to</i> the speed of light, let alone past it. From the Usenet Physics FAQ:

It is a consequence of relativity that the energy of a particle of rest mass m moving with speed v is given by

      E = mc^2/sqrt(1 - v^2/c^2) 

As the speed approaches the speed of light the energy approaches infinity. Hence is should be impossible to accelerate an object with rest mass to the speed of light and particles with zero rest mass must always go at exactly the speed of light otherwise they would have no energy.

http://math.ucr.edu/home/baez/physics/Relativity/SpeedOfLight/FTL.html

141 Name: Anonymous Scientist : 2008-02-16 11:02 ID:o2Omsbkr

However, none of that explains why time only flows in one direction

142 Name: Anonymous Scientist : 2008-02-16 17:36 ID:o/K6QW7l

>>140
As I said, that only deals with sub-light stuff and using actual down-to-Einstenian-mechanics forces. You can't just use good old classic mechanics when talking about time travel and say oh noes, FTL (faster than light) is impossible.

There could well be a way to "jump" to FTL space and skip the whole energy going to infinity problem. And what I said before was compare going jumping forward (or whatever direction) in space faster than light to jumping forward in time, oh, faster than the current pace time is going. I just never thought of it like that before.

>>141
Time paradox.

143 Name: Anonymous Scientist : 2008-02-16 17:42 ID:enesCUJn

it is possible. If i get a plane to somewhere far away, i'll find myself in tomorow or yesterday, lol.

144 Name: Anonymous Scientist : 2008-02-16 18:24 ID:o2Omsbkr

>>142

>Time paradox.

That's no answer,... You could imagine a boatload of Space paradoxes (ubiquity, or several objects at the same place), none none prevent you from moving in all directions of space.

145 Name: Anonymous Scientist : 2008-02-16 19:57 ID:Heaven

>>As I said, that only deals with sub-light stuff
>>that only deals with sub-light stuff
>>sub-light

PROTIP: Star Trek is fantasy.

146 Name: Anonymous Scientist : 2008-02-16 20:19 ID:dFSPKAAa

>>144

I'm not sure that you can just turn around and move in the opposite direction through time.

Even though time is a dimension, the arrow of time is a consequence of thermodynamics. Since entropy must always increase,
there is an entropy gradient from 'past' to 'future' across the time dimension. Any information-processing device (such as your brain) is subject to the same physical laws as every other object, and increases the total entropy of the universe every time it it performs an operation. So any information-processor must perceive a total increase in entropy through time in one direction only.

This does not preclude the possibility of closed timelike curves.

147 Name: Anonymous Scientist : 2008-02-16 21:08 ID:Heaven

>>145
PROTOP: This is a thread of time travel.

148 Name: Anonymous Scientist : 2008-02-17 01:16 ID:o2Omsbkr

>>146
You bring up the classic point of linking time and entropy. Thats fine with me, except for two things:

We use entropy to the issue because it's one of the rare physical laws which is not symmetric, and could thus explain the perceived irreversibility of time.

However you don't know for instance which one is the consequence of the other, or if they are both the consequence of a third unknown factor, or if they have nothing to do, but are both instances of irreversible effects.

Also, if bidirectional time travel exists, then it would increase entropy in the past, which in turn would increase entropy in the future. If so, there would be no obvious break in the second thermodynamic law when you time travel.

Finally, and as you hint, you must take into account the whole system, when you assay the increase in entropy, and thus local time jumps would be possible at the expence of entropy increase somewhere else in the system. Basically, we don't know the link between irreversibility of time and entropy, so it's a bit difficult to explain one with the other. But it's a good starting point for speculation,...

149 Name: Anonymous Scientist : 2008-02-17 01:56 ID:MK0OTpW5

>>141
How do you know time only flows in one direction, or at all?

150 Name: Anonymous Scientist : 2008-02-17 04:02 ID:o/K6QW7l

>>148
How would local reversal of time work though? I tried imagining it and I just can't come up with anything that makes sense.

One, you can't just hop into a time machine and watch the world outside reverse itself. The world is huge and it will take an immense amount of energy...if it's even remotely possible, what with all the tiny atoms and energy and stuff.

You can have an isolated system though, and forward and reverse the stuff inside from the outside (now idea how, but it makes sense).

But let's say we have a bit of space where time is going in reverse. If you throw a rock (or yourself) in there, how is it going to interact with the space?

151 Name: Anonymous Scientist : 2008-02-17 12:02 ID:FQiRyXDB

>>150

We have trouble understanding time, because we spend all our life immersed in it. It's a bit like air: in the past people did not realised that air is not just space between objects, it's something in itself. Of course there were hints (water/air interface forming bubbles, winds). Nowadays it's much easier to understand air, because we see all the time applications of our knowledge of it (airplanes, etc).

I have no knowledge of reverse-time physics, but it's not a problem in this case, because all your questions equally apply to time flow variations: as you may know, the flow of time you're in depends on the mass surrounding you and on your speed.

So if you are travelling at close to the speed of light, your time will be very different from all surrounding objects which travel at a slower speed. As you can see, you can induce a local variation in the flow of time without requiring infinite amounts of energy. One could extend the reasoning and assume that you can vary the local flow of time to such an extent, that you might locally revert it. The conceptual difficulties are the same in both cases.

As for your question with the rock, you just have to think about black holes. In a black hole the mass is infinite, and the flow of time is ripped apart (and I think nobody knows what's going on inside a blackhole). So if you throw a rock into the black hole, as the rock travels space, the flow of time it is subjected to will slow down until it reaches singularity, and then it's anyone's guess. Some people have even suggested that matter could emerge in other points of space or time through white holes (it's not only time which is ripped apart, but space too).

152 Name: Anonymous Scientist : 2008-02-17 12:06 ID:FQiRyXDB

>>151

Oops, I meant to say 'In a black hole the mass DENSITY is infinite,...'

153 Name: Anonymous Scientist : 2008-02-17 17:16 ID:o/K6QW7l

>>151
In my previous post, I was thinking of time as a consequence of the movement of matter and energy but that's not the case obviously, space-time and all that. So you wouldn't need infinite energy to change your perception of time outside you (or your frame of reference). You need to somehow change your frame of reference so that the outside world is reversing to you. Argh, I need to properly understand special relativity to actually begin to make a guess at this.

154 Name: Anonymous Scientist : 2008-02-17 17:21 ID:CrGUsWlF

>>152
Not necessarily. In order for it to be defined as a black hole, the mass density need only be sufficient that light cannot escape.

155 Name: Anonymous Scientist : 2008-02-17 18:27 ID:FQiRyXDB

>>154

We are both right, but at different time points,... You are right that mass density does not need to be infinite to CREATE a black hole (otherwise you'd need infinite amounts of matter and there would be no black holes). What really counts is the amount of matter bound by the gravity well. If this amount is enough to cause collapse and a singularity to occur (a black hole), then the mass density will become infinite. This is why it's called a singularity: all the mass collapsed to a single point in space, the singularity, hence mass density is infinite.

All black holes have the same mass density (infinite), what differs is the amount of mass contained within the singularity. The higher the amount of mass, the wider the event horizon (distance from which light cannot escape the black hole).

156 Name: Anonymous Scientist : 2008-02-18 12:48 ID:sf6Yn2sp

>>153

Special relativity won't get you much. You need general relativity, and that actually intuitively understanding that may require being insane.

On the topic of time and entropy, though, I recently saw the suggestion made that maybe time itself is only a macroscopic property. That would go some way towards explaining why it's so incredibly hard to define a direction of time from the microscopic theories.

What exactly that would mean in practice sure is food for thought, but without a functioning quantum theory of gravity it may be impossible to even speculate.

157 Name: Anonymous Scientist : 2008-02-18 16:15 ID:idwUBqtg

>On the topic of time and entropy, though, I recently saw the suggestion made that maybe time itself is only a macroscopic property.

Hard to accept that,... Gravity does not play a role at microscopic scales, but space and time do. Particle accelerators show relativistic effects on time affecting the particles. So it seems it's sleight of hand to suddently consider time a macroscopic property.

158 Name: Anonymous Scientist : 2008-02-19 10:03 ID:CrGUsWlF

>>157
That, and also many kinds of subatomic particles have measurable half-lives which are extended by relativistic travel. This seems to contradict the idea that time is a macroscopic property only.

159 Name: Anonymous Scientist : 2008-02-19 14:19 ID:E4evLiqi

I think that was more specifically the direction of time being a macroscopic effect, or the flow of time.

160 Name: Anonymous Scientist : 2008-02-19 14:51 ID:o/K6QW7l

>>159
What does that even mean?

161 Name: Anonymous Scientist : 2008-02-19 15:49 ID:idwUBqtg

>>159

I don't see why direction would be macroscopic, while flow remains microscopic. That sounds like a heap of ad hoc contrived postulates,...

162 Name: Anonymous Scientist : 2008-02-19 16:17 ID:uTBmth22

ITT we get confused because we used English instead of maths.

163 Name: Anonymous Scientist : 2008-02-19 17:42 ID:MK0OTpW5

Why would you say time has a direction, or flow?
Space does not have direction or flow.

164 Name: Anonymous Scientist : 2008-02-19 19:01 ID:idwUBqtg

>>163

> Why would you say time has a direction, or flow?

Direction: from pas to future
Flow: as your speed/mass increases, your times slows down compared to other objects.

> Space does not have direction or flow.

Direction: space has three (proven) directions, that's why we speak of 3D, three dimensions.
Flow: actually space seems to have a flow, since the universe is expanding. According to latest discoveries, this expansion (called inflation) could eventually lead to disintegration of galaxies, stars, etc,...

165 Name: Anonymous Scientist : 2008-02-19 20:02 ID:TZ2BDyKP

>>161

That is not what I said. I used "direction" and "flow" as different descriptions of the same thing.

>>163

I would say this because it is extremely obvious that it has. Answering the question of why it does is what this was all about.

166 Name: Anonymous Scientist : 2008-02-20 14:16 ID:o/K6QW7l

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167 Name: Anonymous Scientist : 2008-02-20 14:53 ID:idwUBqtg

>>166

Loud but short of arguments,...

Newtonian physics causality is independent of time direction. If time started going reverse, it would work equally well.

168 Name: Anonymous Scientist : 2008-02-20 23:01 ID:CrGUsWlF

ITT we are wholly unfamiliar with Feynman diagrams.

169 Name: Anonymous Scientist : 2008-02-20 23:30 ID:o/K6QW7l

>>168
You mean Minkowski diagrams.

170 Name: Anonymous Scientist : 2008-02-21 02:18 ID:CrGUsWlF

>>169
No, I am talking specifically about Feynman diagrams, with time as one axis and space as the other, in which one can see plots of wonderfully counterintuitive ideas like an electron bouncing back and forth in time, turning into a positron when it's traveling backwards, and annihilating itself in a flash of gamma rays, which become an electron-positron pair that is the original electron/positron.

171 Name: Anonymous Scientist : 2008-02-21 02:20 ID:MK0OTpW5

>>164,165
I would say time doesn't have a 'flow', because like we move through space, we move through time (if this perspective is not just a product of a weak three-dimensional brain interpreting the world the only way it can).
Unprovable philosophy and nitpicking semantics, I know, but this thread is about time travel. Complete speculation.

> space has three (proven) directions, that's why we speak of 3D, three dimensions.

Whoa, whoa -- slow down, egghead!

172 Name: Anonymous Scientist : 2008-02-28 16:20 ID:Heaven

Wouldn't time travel backward require undoing entropy?

173 Name: Anonymous Scientist : 2008-02-28 22:46 ID:XDpQDIXS

>>172

Not if you increase entropy as you move backwards in time,... this has already been discussed ITT

174 Name: Anonymous Scientist : 2008-03-03 15:52 ID:Heaven

My bad... just asking.

175 Name: Anonymous Scientist : 2008-03-28 06:39 ID:jaX/YWTO

Scientists still believe in time to such a degree that they suggest it is possible to travel through it, just because they've discovered it's just illusional.

Time and travel is the exact same thing, "time travel" is a pleonasm.

You may create such circumstances, through a variety of ways, that you may percieve you're travelling into the "future", sleeping is an easy and natural way to do this. However you cannot travel into the past because there is no such thing, there is only now, and memories of what we're doing in it in different places and other circumstances. Everything is happening at the same time everywhere, but at different locations, being observed at different places. Things are moving through distance, you're observing it through distance. You get a mental image of what you're looking at now, things move and it changes but it is still now, not in the future, and what you just saw wasn't in the past. You call that time, it's more like movement. The sun setting is movement, the universe expanding is movement, you getting older is movement. Within the limit of what speed things may travel, things may happen "faster or slower", but in the end it all comes down to how we percieve it, which is linked to the functions of our brain. It gives us an illusion of time, just as it gives illusions of colours and sounds, other things that do not actually exist.

You're all just musing over a fictional concept with your fractured apprehension of what is real.

176 Name: Anonymous Scientist : 2008-03-29 00:53 ID:MK0OTpW5

> Scientists ... time ... discovered it's just illusional.
> illusions of colours and sounds, other things that do not actually exist.

'Scientists' have also discovered the phenomenon of your mother being so morbidly obese, the only method by which you could theoretically have escaped her reproductive organs is through thermal radiation with a black body spectrum.

177 Name: Anonymous Scientist : 2008-03-29 02:23 ID:jaX/YWTO

>>176
lol
I guess that's your way of saying, that you think I'm wrong. Why not try to convince me instead?

178 Name: Anonymous Scientist : 2008-03-29 04:42 ID:sW+pmhcT

If time is "illusional" then space is too. So find the frequency of the illusional vibration, put it into a computer and wire someone with it. Hop, a time/space machine. :)
See http://en.wikipedia.org/wiki/Montauk_Project

179 Name: Anonymous Scientist : 2008-03-30 06:00 ID:SDrd4fDR

>>178
nooooo!!!
The frequency of the illusion would be a non-physical energy frequency, there probably is no physical frequency. The only way to do it is to master astral pojection, probably. Very scientific.

180 Name: Anonymous Scientist : 2008-03-31 01:15 ID:sW+pmhcT

>>179
Well, if the person can master astral projections, then he can view the past using the Akashic Records.
http://en.wikipedia.org/wiki/Akashic_records

He would have no need for a time machine.

181 Name: Anonymous Scientist : 2008-03-31 04:17 ID:SDrd4fDR

that was my point. Akashic records, or, just find the past, and go hang out in it, lol. Probably just going to the past would be a better idea... you're not really supposed to use the akashic records for entertainment.

182 Name: Anonymous Scientist : 2008-03-31 04:22 ID:SDrd4fDR

Forgot to add-
The thing that had me interested was the possibility of there being an identifiable energy frequency... if someone could find that, it would maybe be a much more accurate way to time travel astrally, instead of just trying to do it, or ending up in the past somewhat randomly. Though then it seems likely that this frequency is alreadfy tied to the akashic records.... hmmm. Anyway, it sounds like something well worth looking into, for real scientists and astral projectors alike.

183 Post deleted.

184 Name: Anonymous Scientist : 2008-04-02 16:05 ID:o/K6QW7l

Hey guys, what do you think of this? Time travel is like a feedback loop connect back through a second dimension of time. And all the changes and paradoxes can be explained by changes that happen in the feedback loop until it stabilizes.

185 Name: Anonymous Scientist : 2008-04-03 08:44 ID:jaX/YWTO

this is fucking idiotic

186 Name: Anonymous Scientist : 2008-04-03 14:05 ID:sW+pmhcT

"The Cambridge physicist Professor Stephen Hawking spent much of his career attempting to prove that time travel is impossible. If it were possible, he reasoned, why have we not been visited by voyagers from the future? But he was forced to conclude that there is actually nothing in the laws of physics that prevents moving in time.

"He changed his mind about 10 years ago," said Kaku, "There was no way to ban time travel from happening. So now he says that time travel is possible, but not practical."

The way it might work would be to take a trip through a worm hole connecting one point in space and time with another. The laws of physics suggest that the intense gravity of a black hole is enough to rip the fabric of space and time, making a worm hole possible.

"What we physicists want to do is create our own wormhole so that if you walk through the looking glass you may go backwards in time," said Kaku. Stabilising a black hole would require large amounts of an exotic form of energy called negative energy, thought to be impossible. "But we can now make it in the laboratory," said Kaku."
http://www.guardian.co.uk/science/2008/apr/02/sciencenews.physicalsciences

187 Name: Anonymous Scientist : 2008-04-04 00:39 ID:o/K6QW7l

>>185
u're fucking idiotic.

188 Name: Anonymous Scientist : 2008-04-10 07:52 ID:lgK52Yx4

Time doesn't actually exist, it's just a social construction to measure change. Of course time travel is not possible. Assuming the laws of the universe holds true and applies that is.

189 Name: Anonymous Scientist : 2008-04-10 16:05 ID:h3UAXBQj

Space doesn't actually exist, it's just a social construction to measure change. Of course space travel is not possible. Assuming the laws of the universe holds true and applies that is.

190 Name: Anonymous Scientist : 2008-04-12 01:18 ID:o/K6QW7l

>>189
Physics is just a social construction. We don't really know what is going on beyond this superficial socially constructed mathematical model for what we perceive our physical universe to be.

Time is just a concept made up by us to explain changes that happen around us. It doesn't really exist; it's just change. Causality. Which is just a concept constructed by humans. It's just a mathematical model to explain cause and effect. Therefore, time doesn't actually exist.

191 Name: Anonymous Scientist : 2008-04-12 03:34 ID:MK0OTpW5

>>190

You're just spouting philosophical rhetoric.
Which is just a concept constructed by humans.

192 Name: Anonymous Scientist : 2008-04-12 17:11 ID:QPZM8lgA

>>190 is just a social construction. We don't really know what is going on beyond this superficial socially constructed mathematical model for what we perceive this message board to be.

4-ch is just a concept made up by us for the lulz. It doesn't really exist; it's just change. Causality. Which is just a concept constructed by humans. It's just a mathematical model to explain cause and effect. Therefore, >>190 doesn't actually exist.

193 Name: Anonymous Scientist : 2008-04-12 20:04 ID:o/K6QW7l

>>191
No I am not. What I am saying is the truth.

>>192
Of course I exist. I can think and I can see me, so I know I exist and I can see everything around me, so I know they exist. But physics is just mathematics which is socially constructed and not real. So you can't just say time is real by using physics as proof of it. I can't see time. I can't measure time; clocks only measure themselves, not time itself. So it really doesn't exist, it's just causality.

194 Name: Anonymous Scientist : 2008-04-13 00:36 ID:Heaven

> I can't measure time; clocks only measure themselves, not time itself. So it really doesn't exist, it's just causality.

You can change time. That alone should give you a hint that it exists.

But you can't change causality. Thus, time and causality are distinct concepts.

195 Name: John Titor : 2008-04-13 01:05 ID:ylRqS0DE

It's possible.

196 Name: Anonymous Scientist : 2008-04-13 21:00 ID:Heaven

>>193

> I can see me, so I know I exist and I can see everything around me, so I know they exist.

False. You are solely a brain suspended in a vat of fluid. Everything your experience with your senses is merely your brainself being probed with electrical charges.

197 Name: John Titor : 2008-04-14 09:14 ID:ylRqS0DE

I'm going to be visiting earlier in this thread to prove it's possible. Just thought you should know!

198 Name: Anonymous Scientist : 2008-04-14 09:15 ID:Heaven

>>197

Oh, Titor! Choice performance, my friend! Choice performance indeed!

199 Name: Anonymous Scientist : 2008-04-15 05:26 ID:Nm9Ibg3H

>>196
That still = the person and their surroundings existing. Simply in a different form and context than what was percieved, doesn't cancel out the existence. That's similar to saying that because people a few hundred years ago thought the world was flat, that their world didn't exist. It sure wasn't flat, but it definitely existed.

200 Name: Anonymous Scientist : 2008-05-09 15:46 ID:Heaven

>>199

>>It sure wasn't flat, but it definitely existed.

No it didn't, it was just a social construction.

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