h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

We went through that problem with Johnny B Goode in Back to the Future. I'm still trying to work it out.

Has it ever occured to you that we are travelling backwards in time?

sure we are travelling in a direction (from the past to the future)we just assume thats forwards because its the direction we are going,but if you think about it,we are facing the oppisite way.

We cannot see the future,(the direction we are travelling)only the past(the direction we have come from).Therefore we are not travelling in the direction we are facing but in fact the oppisite direction or backwards.

You may argue that we do not see the future or the past only the present.

To answer this i will point out that when you look at the stars you do not see them as they are now, but as they were in the past,maybe a hundred or even thousands of years ago.This is because of the time it takes for the light to travel to reach your eyes

.It works the same up close, it takes time for the light from your computer screen to reach your eyes, even more time passes while your brain decodes these light impulses,only a very short time,but none the less everything you see (or experience any other way) is in the past.In brief any event must occur before it is seen,and so we must be looking towards the past and travelling towards the future,thats backwards.

The problem,stevezero, is thereby not to travel in time, but to turn our perspective around and look back into the future.

that can give you a sore neck

This subject is also being beat to death in another thread called "anything about time travel"

http://www.h2g2.com/F19585&thread=18581&skip=0&show=20

Mostly

I didn't read all of the replies, but:
I would begin with the first basic thing;
what is time?
Did we ever talk about what is space, or WHAT will we do WHEN we know how to TRAVEL in space ? No. It is such a natural thing to move oneself somewhere that there's no need to find out. So maybe the question is wrong, but one thing I am sure of: we dont know what is time

Hmm, I´m amazed the time travel discussion is still so small. But here´s my two cents.

To they guy who said the many world theory had many critics, that´s actually not true. It would be more correct to say that basically nobody believes in it. There are only very few scientists who believe in the idea, and it really doesn´t seem to be something we would ever be able to verify or falsify. So instead of sitting here talking about it, go out and start a religion based on the theory

And to the dude talking about us facing the past, that seems to me to be just a matter of terms. It´s true that everything we experience is past, but saying we face the past because of that seem to be wrong. That´s only what you´re saying cos the eyes sit in front of your head. If you were an alien species with the eyes in the back, you would be claiming that we are facing the future because everything you see is in the past Actually there has been made a sci-fi story with the concept: What if we are travelling from the future to the past, and therefore going to end up in a swamp as amoebas, but just doesn´t dare to face it and tell ourselves we are going against the future.

To the guy who criticize historians for shaping history, I´d like to hear your view on how history actually happened.

As Soeren Kierkegaard said: Life should be lived forwards but understood backwards.

Hey Xanatic
i do realize that its just a matter of terms
i was having a bit of fun with semantics.
since i first got the idea you are the first person to point out that we call it facing coz thats where we keep our eyes
well done have a fish
by the way an alien species with eyes on the back of their heads would still walk the way their eyes pointed otherwise they would keep bumping into things

Ah - that brings me to my question - posed somewhere in this forum - you might have to click back a few red dots - "Why are humans so bady designed". I, for one, would prefer to have eyes in the back - as well as the front of my head - if anyone was going to redesign us.

and there must be a dozen conversations on the subject of time travel. Just search for it, the list is endless, although some references are to "time" or "travel", but there have been many in-depth theorisings about the subject.

Most animals are either hunters or hunted. Hunters, such as cats, tend to have eyes in the front of their head, so that they can see one thing very clearly and chase it. Hunted animals such as rabbits tend to have eyes on the side of their head, giving them less detailed vision over a much larger range. In some cases, full 360 degree vision is possible. I've heard that both ducks and rabbits can see the whole way round and this is actually "having eyes in the back of your head".

Although humans spent a brief million years as hunters on the plains of Africa, we evolved our forward facing eyes before that, when we lived on fruit and vegetables. It's hard to see why we should have forward facing eyes for hunting a pear or a pomegranite. Maybe the place that humans evolved did not have any big predators, so we didn't need to run away and didn't need eyes in the back of our heads.

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To do a timetravel, to the future, you need two thngs, a lot of energi and someone crasy enough to do it.
To get the crasy person isnt so hard, but that energi is a problem.
You need the energi to accelerate to the speed of light, couse then the time stopes for the person/s that are traveling.
Now think that the the universe is round, then you have to come back to the point that you started at and then the time has moved there but not for the traveler.
Now, there is two problems with this idea.

1. The travelers body will be cruched under the g-forces in the start.

2. The speed of light is the fastest speed possible, and in a round universe the turning will slow down the speed, and then you can't travel in a constant speed of light.

Here's another paradox:

If I went back in time say 20 years and killed the younger version of me, then I would not exist and could not go back and kill myself, so I would still exist, so I could go back and kill myself, but then I wouldn't exist so.................etc etc etc

Perhaps time travel is possible but all time travellers are stuck in a loop somewhere?

Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...Say that again, Spoot ...

You don't need huge g-forces. An acceleration of one g (9.81 m/s2) will simulate gravity. Spend 10 years accelerating at 1g, 10 years decelerating until you are stationary at some distant point in the galaxy. Then spend the next 20 years coming back. You will be 40 years older, but thousands of years will have passed on Earth. You don't need to reach the speed of light (which you can't do anyway) and you don't need a "round" universe (closed).

The problem with this is that there is only one way to accelerate something in space, and that is to throw something out the back of your spaceship. The faster you throw it, the more effect it will have. Your spaceship will lose mass, meaning there is less left. Eventually you will have nothing left to throw out, so further acceleration will be impossible. Some science fiction writers have used hypothetical "magnetic scoops" which can collect up instellar hydrogen and use that as fuel, but these are completely fictional as yet.

To Stevezero: I know an alien probably wouldn´t have eyes in the back of the head. but I was just using it as an example.

About humans eyes pointing "forwards" before they started hunting, isn´t that mainly a question of when to look? Before we were monkeys we were another animal, and somewhere along the line we were probably an animal that hunted it´s food

To Spooot: That is really THE time paradox isn´t it. To me it seems there´s only two solutions. If you live in year 2000 and go back to 1960 to kill you mother, it should already have happened. Cos it should have happened 40 years ago. So it is impossible to change time, because if you could it would already have been done. The other option is time is like a river. Imagine you standing on a small boat in the year 2000 flowing downstream. You then throw a small stick into the water behind you which is 1960. The stick will also flow downstream, but because you´re both moving there will always be those 40 years between you. So if you go back to 1960 and kill your mother, then travel forward again, you will see that nothing has changed. But if you went back to 1960 again, what would it look like then? Would your mother be dead or would everything have been reset when you left? I read a nice little story about changing the path of time, but I won´t start to summarize it here unless you want me to.

Quite - I always say that, too. There is only ONE 1960. So if you go back and kill yourself or your mother, you won't have been there in the first place to go back. Because even if you are coming from 2000, what happened in 1960 happened in 1960 and not in 2000, travelled back to 1960. So what we have now is the result of anything that ever happened, even if someone went back and did it.

I'm always trying to explain this and people won't believe me. Unless of course you start the parallel universe theory. I can live with that. (I've got to, I read the DNA books) and then all things are possible in all ways.

Okay, I´ve never understood this. Where does the N in Douglas Adams come from? Everybody refer to him as DNA, what does the N mean?

The idea of travelling "through" time as if it were a space is an interesting delusion. Our perception of time as a space (sort of like calling the diffuse network of communication pathways and machines that make up the internet a space we can play in - cyberSPACE) seems to be rooted in the fact that we translate almost all of our more abstract ideas into mental "space" representations, possibly because our visual sense has been so vital to our evolution and survival. I know that when I look at my watch (analog, not digital) I perceive the time remaining to an appointment as sort of a spatial feeling (anyone else?). My hunch is that time as such does not exist and is simply the way our minds perceive the fact that energy systems (Life, the Universe, and Everything...) tend toward a generally more disordered state (entropy). So, time travel into the "past" is actually the desire to recreate an infinitely complex set of energy configurations that have lapsed and evolved into a different form (NOW). The "future" of course exists as a space or destination no more than the "past". A similar situation exists in what we see around us. Our senses tell us we are seeing a forest around us, smelling the foliage, and feeling the breeze and the trail under our feet. But how else should we interpret the true nature of these things? As individual photons with complex electromagnetic and quantum properties? As nasal receptor sites registering the molecular geometry of scent molecules? As the near field interactions of atoms causing the ultimate release of nerve impulses and neurotransmitters? No? So we invent TIME. No travelling. Sorry.

I never have time before appointments.