Time Travel

Off Topic
81

[quote]ZEB wrote:
Apparently one theory states that if we can build a time machine we will then immediately begin getting messages from the future, as they will obviously have one as well. However the past is another matter.

The same theory states that we cannot go back in time as there is no time machine in the past. Apparently it’s like a form of communication in that you cannot communicate with someone who does not have a telephone or a computer etc…[/quote]

If this were true then you would be solving your own problem. You would be having a reciever in the “past” for those in the “future” but only to time in which the machine existed.

Ok I’m going to put in another theory because I love this stuff. Like I said in my previous post, no one would no whether there has been time travel to either past or future because, for that dimension time travel would be common. So, my theory is we are already living in hundreds and millions of ways and times, based on our decisions. I think that time splits with each decision. So within my theory, because I typed “d” I am in a more dimensions and leading more and more lives.

This however beings up another topic, which one am I living in and why? Why do I stay in conciousness with this body?

82

Also, backwards time travel makes “Intelligent design” absurd. God wouldn’t have to fix things along the way, he could fix them from outside of time.

83

[quote]nephorm wrote:
pookie wrote:
Now the trick question: If you turn on a flashlight in your spaceship, how fast will the light be moving, relative to you? Relative to some outside observer?

Same speed to both.[/quote]

We just discussed this in my physics class and this is the most difficult concept for me to understand. I realize that it is the same because I was told so, but I don’t understand “why”. If you do, please tell me because, due to relative travel, it should be different depending upon the speed of the individual.

84

[quote]ZEB wrote:
Hey pookie what about this?[/quote]

What the Bleep Do We Know? is not the way to learn about quantum mechanics. The whole movie is clap-trap gobbledigook made to sound good using scientific terms to mean things they don’t mean at all.

The only reputable physicist they interview had his segment edited to show he supports their crackpot views when in the unedited interview he was trying to explain why they were wrong.

And that woman chanelling an Atlantis warrior dead for 35,000 years? Right.

[quote]If you were to be able to seperate atomic particles you find that there a 3 things, Quarks, Leptons, and Force Carrears. Scientific evidence shows that thes “basic particles” are constantly dissapearing and reappearing.

I demand to know where these particles are going![/quote]

Those would be “force carriers” I guess?

Our “Standard Model” for the physical particles doesn’t have them “disappearing and reappearing” constantly. It simply happens to be impossible to know both a particle’s location and direction at the same time. The more precisely you measure one of those two; the more you affect the other one. The particles are also generally depicted as “clouds of possibilities” and have as such no precise location until observed.

The old model of the atom as a small solar system is the completely wrong way to imagine the inside of an atom.

A good layman introduction to QM is “In Search of Schrodinger’s Cat” by John Gribbin. http://www.amazon.com/gp/product/0553342533/sr=8-1/qid=1139791408/ref=pd_bbs_1/104-3371922-5419115?_encoding=UTF8 Except for the part about the multiverses, which I’m find hard to swallow, the first three third of the book is quite accessible and clearly explained.

85

[quote]BlakedaMan wrote:
However, time travel into the FUTURE is more plausible because it is unexplored for those who have been left in the present, which would then be the past.
[/quote]

“Traveling” to the future isn’t a problem if you can get close enough to the speed of light for time dilation to be heavily noticeable. As time would pass slowlier for you than for those left back on Earth, you could travel for a few weeks and get back after a few thousand years had passed on Earth.

It is a one-way trip, though. You couldn’t get back. Unless new physics had been discovered in those 2000 years on Earth. :slight_smile:

As for getting to far from Earth while going that fast (mentioned in some other post), just turn around mid trip and head back for Earth. Adjusting for the trip of the solar system thru the galaxy and of the galaxy thru the universe, of course.

86

[quote]BlakedaMan wrote:
nephorm wrote:
pookie wrote:
Now the trick question: If you turn on a flashlight in your spaceship, how fast will the light be moving, relative to you? Relative to some outside observer?

Same speed to both.

We just discussed this in my physics class and this is the most difficult concept for me to understand. I realize that it is the same because I was told so, but I don’t understand “why”. If you do, please tell me because, due to relative travel, it should be different depending upon the speed of the individual.[/quote]

Geometrically, its because the more energy that is added to a light beam, the more “oblique” is its path through space and time, because space and time are curved.

87

[quote]BlakedaMan wrote:
We just discussed this in my physics class and this is the most difficult concept for me to understand. I realize that it is the same because I was told so, but I don’t understand “why”. If you do, please tell me because, due to relative travel, it should be different depending upon the speed of the individual.[/quote]

Because the speed of light is constant in a vacuum for all observers in all reference frame. Hence, since the speed of light does not change, it is time that changes (ie, it is “relative” to the observer and his frame of reference).

So everybody observes the same occurence but arrives at different conclusion because time doesn’t pass at the same rate for all of them.

Previous to Einstein’s relativity, it was believe that time was absolute and passed at the same rate throughout the universe no matter where you were or how fast you were going. Not so. The speed of light is the constant, not time.

88

[quote]BlakedaMan wrote:
Ok I’m going to put in another theory because I love this stuff. Like I said in my previous post, no one would no whether there has been time travel to either past or future because, for that dimension time travel would be common. So, my theory is we are already living in hundreds and millions of ways and times, based on our decisions. I think that time splits with each decision. So within my theory, because I typed “d” I am in a more dimensions and leading more and more lives.[/quote]

Have you heard the theory of “quantum immortality?” If the universe really “splits” at every decision, then everytime there’s a chance you could die, there’s a split and in one universe you die, and in the other one you live.

If your consciousness stays with the living copy, then you’ll never die, because there’s always the off chance that you’ll live for one more day, and in one of those split universe, you did.

You’ll grow to extremely old age, while people around you eventually die (since statistically, you’ll eventually remain on the side where they died during one of their “split”).

Cool, no?

89

Well, I read up to the middle of the third page, so I appoligise in advance if this has already been discussed.

I was originally going to argue about not being able to go into the past, because right now, there is no evidence of anyone ever coming into the past as of yet, from any time in the future. So if it is possible, then we will never figgure it out.

Then what Zeb was saying about not being visible, or being holographic, and not being able to affect the past would make sence (except that being holographic can affect it, so maybe unseen altogether would be best).

Then I was thinking that time travel can explain UFOs and Aliens in a couple of ways.

They could be people from the future in specially designed crafts that can reach the speed of light or go faster, but keeps the occupants safe somehow beond our ability to comprehend.

Or, they could actually be from another planet far enough from Earth that we haven’t been able to see where they are from, and they are only able to get here because they can travel so close to the speed of light that they have enough time, relative to themselves, to make it here and back.

Very interesting stuff. I think I’ll finish reading page 3 and 4 now.

90

[quote]pookie wrote:
Panther1015 wrote:
Disagree. It was clearly a scientist that wrote such a quote. It’s the engineers that can build anything with enough time and money. The scientists come up with the theories and use the scientific metho to prove or disprove them. Engineers create the tools that apply these newly discovered paradigms into practical use in the real world.

And neither scientist nor engineer can violate the basic physical laws that govern the universe.

Let’s say you figure out a way to travel thru time, BUT it requires an infite amount of energy. Guess what: no time travel for you!

[/quote]

“Basic physical laws” as you put it are being challenged every day. Maybe it’s more likely that our understanding of world around us is pretty limited and thus our perceptions of what’s possible as well.

91

Time is not a spacial dimension and can therefore never be navigated forward or backwards.

http://www.rebelscience.org/Crackpots/notorious.htm

Louis Savain:

People often talk about the passage of time. They say that time flows or changes. However, logically speaking, it is a fallacy that time changes. Clocks change, physical processes change but time is invariant. Why? Because, again, ‘changing time’ is self-referential. The truth is that nobody has ever observed time changing. We only use the changes in our clocks to derive unchanging time intervals. The nasty and shocking little truth is that time does not change, a million wormhole and time travel fanatics notwithstanding.

The above may come as a shocking revelation to many but it is a logical fact, one that makes a lot of celebrated time travel and wormhole physicists look rather silly.

The whole thing is analogous to the unemployment rate. No one is arguing for its physical existence but it is nevertheless useful. The same goes for time. Just as the unemployment rate is derived abstractly from the number of employed and unemployed people, time is also derived abstractly from the magnitude or rate of motion or change. It is only when one decides to make time an independent variable or a dimensional axis (degree of freedom), that one moves into crackpot territory.

92

Well, if anyone at any time in the infinite future is going to build a time machine, they haven’t come back and told ME about it.

yet

93

whoops

94

All time is essentially singular.

Think of it - the future iteration of the Universe depends on everything happening now, in a certain specific way, to develop into that future Universe-state. Similarly, the present iteration of the Universe depends entirely on the past iteration; that everything as it is now, depends wholly on that as it was in the before-state.

But this works in the other direction as well! Nothing in the present could be any way other than it is, otherwise the past would have had to unfold differently, to have had a different character. So the past is dependent wholly on the present as well. And so it follows that if the future is to occur in some certain way - and we only know the Universe to ever exist in some certain state - then our present is also tied to this next iteration.

The argument here seems stronger that the past depends on the present, due to our general thought of the past being now unchangeable, but it certainly follows that the present-state is also wholly dependent on whatever shall be the future!

We generally recognize that future is dependant on present, which is dependant on past. But we see it is also true that past is dependent on present, which itself is dependant on future.

Therefore, all is interdependant, and nothing can be other than it is. :slight_smile:

Serenity Prayer -
God grant me the serenity
to accept the things I cannot change,
courage to change the things I can,
and wisdom always to tell the difference.

95

[quote]pookie wrote:
ZEB wrote:
Hey pookie what about this?

What the Bleep Do We Know? is not the way to learn about quantum mechanics. The whole movie is clap-trap gobbledigook made to sound good using scientific terms to mean things they don’t mean at all.

The only reputable physicist they interview had his segment edited to show he supports their crackpot views when in the unedited interview he was trying to explain why they were wrong.

And that woman chanelling an Atlantis warrior dead for 35,000 years? Right.

If you were to be able to seperate atomic particles you find that there a 3 things, Quarks, Leptons, and Force Carrears. Scientific evidence shows that thes “basic particles” are constantly dissapearing and reappearing.

I demand to know where these particles are going!

Those would be “force carriers” I guess?

Our “Standard Model” for the physical particles doesn’t have them “disappearing and reappearing” constantly. It simply happens to be impossible to know both a particle’s location and direction at the same time. The more precisely you measure one of those two; the more you affect the other one. The particles are also generally depicted as “clouds of possibilities” and have as such no precise location until observed.

The old model of the atom as a small solar system is the completely wrong way to imagine the inside of an atom.

A good layman introduction to QM is “In Search of Schrodinger’s Cat” by John Gribbin. http://www.amazon.com/gp/product/0553342533/sr=8-1/qid=1139791408/ref=pd_bbs_1/104-3371922-5419115?_encoding=UTF8 Except for the part about the multiverses, which I’m find hard to swallow, the first three third of the book is quite accessible and clearly explained.

[/quote]

I never said the movie was a good way to learn QM, but I do find that particular theory to be interesting. You have no way to support that it is “crackpot” because it is not more of a speculation or well educated guess than the ideas you support.

However, I recognize that you are much more knowligable concerning QM and other related topics so I will take your word for it.

And I would also like to know some of the books you find very good that discuss QM and such, other than the one you said previously. I would like to read into it more as I find it very interesting.

96

[quote]BlakedaMan wrote:
nephorm wrote:
pookie wrote:
Now the trick question: If you turn on a flashlight in your spaceship, how fast will the light be moving, relative to you? Relative to some outside observer?

Same speed to both.

We just discussed this in my physics class and this is the most difficult concept for me to understand. I realize that it is the same because I was told so, but I don’t understand “why”. If you do, please tell me because, due to relative travel, it should be different depending upon the speed of the individual.[/quote]

The way Einstein first thought about it was this: Let’s say I could run really fast so that I was running at the speed of light, what would I see? Well, we know light is a wave, and so I would see a stationary light wave. But, a stationary light wave would violate everything we know about electromagnetism (i.e. Maxwell’s Equations).

So, while everyone likes to talk about relativity as a mechanical theory (using motion of objects relative to each other), it is in actuality an electromagnetic theory. In fact, if you take Maxwell’s equations, which describe the properties of electric and magnetic fields due to charges, magnets, etc, you can rearrange them (after taking some derivatives) such that you get an equation which describes a wave. And every wave equation has a constant which describes the velocity of the wave: well, sure enough there was a constant (consisting of a product of two fundamental constants from E&M), which matched the known value of the speed of light. HOWEVER, in Maxwell’s equations, there is no preferred, or absolute, frame of reference! So, it must be true for all frames of reference…

Of course, it took physicists awhile to make sense of it, but looking back it is quite clear. Hope that answered your question…

97

[quote]Kailash wrote:
All time is essentially singular.

Think of it - the future iteration of the Universe depends on everything happening now, in a certain specific way, to develop into that future Universe-state. Similarly, the present iteration of the Universe depends entirely on the past iteration; that everything as it is now, depends wholly on that as it was in the before-state.

But this works in the other direction as well! Nothing in the present could be any way other than it is, otherwise the past would have had to unfold differently, to have had a different character. So the past is dependent wholly on the present as well. And so it follows that if the future is to occur in some certain way - and we only know the Universe to ever exist in some certain state - then our present is also tied to this next iteration.

The argument here seems stronger that the past depends on the present, due to our general thought of the past being now unchangeable, but it certainly follows that the present-state is also wholly dependent on whatever shall be the future!

We generally recognize that future is dependant on present, which is dependant on past. But we see it is also true that past is dependent on present, which itself is dependant on future.

Therefore, all is interdependant, and nothing can be other than it is. :slight_smile:

Serenity Prayer -
God grant me the serenity
to accept the things I cannot change,
courage to change the things I can,
and wisdom always to tell the difference.[/quote]

Sorry, Kailash, but you have presented a classical (i.e. non-quantum) theory…

On an atomic level, the outcome of an experiment (or any causal event) is not decided absolutely by the setup (or past events), since behaviors of quantum mechanical objects are governed by probablity. So, you can set up two identical experiments (say, to measure the spin of an electron in magnetic field) and you might get different results.

However, your different results would have nothing to do with any slight differences in your experiment, its just that each possible result of your experiment has an associated probability of occuring.

So, don’t fall victim to believing your macroscopic world experience, because Nature does things her way, wether you like it (or understand it) or not.

98

[quote]mertdawg wrote:

Geometrically, its because the more energy that is added to a light beam, the more “oblique” is its path through space and time, because space and time are curved.
[/quote]

Wow, that makes NO sense at all.

First of all, the diagram is awful. Where did you get it? It really doesn’t explain any physics at all.

Secondly, how does one “add” energy to light? Assuming you are talking about a blueshift, the energy does increase, but that only changes the frequency, while the velocity remains the same (as we all know).

Also, we are talking about the special theory of relativity, which does not include the effects of mass (which is what causes spacetime to curve). In the problem with two observers going towards each other with flashlights, it is assumed to be in flat space.

As for the geometric explanation, I think you are referring to a Minkowski diagram, which has time on one axis and space on the other (in the 1D case). Look it up!

Sorry, but I hate bad physics…

99

[quote]Panther1015 wrote:
“Basic physical laws” as you put it are being challenged every day. Maybe it’s more likely that our understanding of world around us is pretty limited and thus our perceptions of what’s possible as well.[/quote]

Not our physical laws, or the understanding we’ve got of them. Our knowledge is of course limited and evolving.

But the actual physical laws of the universe, what String Theory and the other “Theories of Everything” are after. Those basic laws exist and govern the whole of reality. If those laws precluded time travel to the past, you’ll never be able to do so. That’s what I meant.

100

[quote]BlakedaMan wrote:
I never said the movie was a good way to learn QM, but I do find that particular theory to be interesting. You have no way to support that it is “crackpot” because it is not more of a speculation or well educated guess than the ideas you support.
[/quote]

Actually, it is. I know of no, NOT ONE, reputable physicist who supports that movie. Like I said, the only one (David Albert) in it was edited to make him say the opposite of what he was actually trying to say. (See here: http://www.popsci.com/popsci/science/463c0b4511b84010vgnvcm1000004eecbccdrcrd.html , second paragraph…)

Anyone is free to have any idea they want and make a movie about it. Personnaly, theories I find interestig are those that have at least a chance of being connected to reality.

As for books, I’ll make a list later on when I’m home. I’ve got a few interesing links, though:

General - http://scienceblogs.com/
Physics - http://cosmicvariance.com/

String Theory: (there are many others, but those two are, let’s say, opiniated…)
Pro: http://motls.blogspot.com/
Con: Not Even Wrong