Ok, so lets say you use a computer to randomly generate a number. Then you travel back in time and you use the computer again, to generate a number. Would it be the same number?

i'd say no

If the answer if no, you couldn't go back in time and play the lottery game? I think you could, but I also initially thought no to this answer. *head bursts*
Would every random event be different? Would the 1 in a million play in a ball game have failed then?

Computers are deterministic. You'd need a truly random data source.

There is reason to believe that time dilation of an event exhibiting relativistic momentum evinces the characteristics requisite for a prediction of unitary recurrences in Minkowski space, though the development corroborating these sorts of thought-experiments was formulated under an Hegelian supposition that deals with the psyche-corporeality quandary in a cavalier manner. The regression of the Benz plane regulated under an axiom based on the pigeon-hole principle may suggest a contrary conclusion that evidences the popularly-know chaos theory.

source: http://www.wikipedia.org/

Duh.

Depends on the seeding method, and certain "random" generators are better than others.

Digital randomization and physical randomization are different.

The digital randomization would be truly random. Could be ANYTHING.

In the real world, travelling back in time to try and win the lottery will work because the random result will be the same. The balls in the thingy will bounce in the same order and land in the same order unless you somehow alter time--make the person picking the ball take an extra second or two, make the ball randomizer be affected by the wind, etc.

I've tried and I know this is true.

If you're wondering why I'm not rich: I didn't have any cash to buy a new lotto ticket when I got back in time and didn't profit at all.

Oh man I feel sorry for you that must have been so frustrating.

It would not return the same value unless you did it in exactly the same way, or simply observed yourself using the machine such as:

Step 1 (Day 1 - 6:00pm): Jepman hits the random number generator, for the sake of arguement, it returns "59923".
Step 2 (Day 2 - 6:20pm): The Jepman(future) that just did the random number generator goes back in time to watch himself do what he just did 24 hours and 20 minutes ago.
Step 3 (Day 1 - 6:00pm): Jepman is now back in time (Step 1), and watches himself do the process of returning the number "59923" from the random number generator.
Step 3.5 (Day 1 - 7:25pm): Now that Jepman has gone home for dinner, Jepman(future) steps into the time machine and returns to the future!
Step 4 (Day 2 - 6:30pm): Jepman(future) returns from the past, very pleased with how his theory on time travel.

Supposing a time machine did exist, things would happen as they normally would, unless you did something significant enough to change what would normally happen. However, as life itself is very complex, it would be VERY easy to cause a change without realising it.

Such as the classic "winning the lottery" thing, that probably wouldn't work out as great as you thought it would, unless you only travel a very small time frame (24 hours max). Considering you'd have to effectively forget a whole day of your life (since it wouldn't be what happens anymore).

Time travel theory is easy to confuse yourself on, but if you think about things logically and from a "this affects that, that affects this" mindset then it's ok.

You'd have to kick yourself off the computer first; thus creating a time paradox.

This question actually touches on a lot of interesting and mind-bending stuff like causality, multiverse theory, and whether the universe is or isn't deterministic. Time travel is weeeeeeiiiirrrrd.

Hm. No. It all depends. If you went back to the EXACT same timeline, you would get the EXACT same number. This gets all hazy though when you start talking about alternate dimensions. Alternate dimensions refer to things how they are but different in some way. Theory has it that there is an alternate timeline for everything that happens. Consider if you go back in time, it might be a different timeline than the one you just came from. Obviously there isn't much proof that we know of because there is alot of phenomina in the universe that we still can't explain. But if you said that alternate universes exist, I would have to say it would be different and random. However, if it was the same timeline, the numbers would be the exact same because things would just be playing out like a movie; just the only difference is that you have the ability to rewind time and revisit the past.

My assumption is this:

If I were to travel back in time, and generated a number in the exact precise conditions that it was initially generated it, yes the same number would return. Digitally speaking, this is a logical conclusion. However this is speaking out of not knowing exactly how a seed in a random number works.

Is a random seeded number influenced by the milliseconds the program has been operating for? If so, would the same seed at the same milliseconds return the exact same number?

Some experimentation is required, I will see if I can get some spare time to write a program to test this theory, but first I will see how a random seeded number actually works under the hood.

EDIT:
After reading this, I think my theory is right and doesn't need any proving.

I like to think of time as a man-made concept rather than some type of fact.

Mostly because I'm not moving forward in time, I'm just changing my position at the current time.

But that's just me and how I like to perceive things. I'm far from a scientist.

Yeah that's how I see it too.
If time was a real thing, and you could travel back, then history would be set as it is so you would indeed be able to travel back and get the same generated number.
Otherwise, you wouldn't be travelling back in time really, because everything would be different if everything random was random, because, really, EVERYTHING is random.
...or something

Google has some interesting definitions:

# an instance or single occasion for some event; "this time he succeeded"; "he called four times"; "he could do ten at a clip"
# a period of time considered as a resource under your control and sufficient to accomplish something; "take time to smell the roses"; "I didn't have time to finish"; "it took more than half my time"
# an indefinite period (usually marked by specific attributes or activities); "he waited a long time"; "the time of year for planting"; "he was a great actor in his time"
# a suitable moment; "it is time to go"
# the continuum of experience in which events pass from the future through the present to the past
# a person's experience on a particular occasion; "he had a time holding back the tears"; "they had a good time together"
# clock: measure the time or duration of an event or action or the person who performs an action in a certain period of time; "he clocked the runners"
# assign a time for an activity or event; "The candidate carefully timed his appearance at the disaster scene"
# clock time: a reading of a point in time as given by a clock; "do you know what time it is?"; "the time is 10 o'clock"
# set the speed, duration, or execution of; "we time the process to manufacture our cars very precisely"
# fourth dimension: the fourth coordinate that is required (along with three spatial dimensions) to specify a physical event
# meter: rhythm as given by division into parts of equal duration
# regulate or set the time of; "time the clock"
# prison term: the period of time a prisoner is imprisoned; "he served a prison term of 15 months"; "his sentence was 5 to 10 years"; "he is doing time in the county jail"
# adjust so that a force is applied and an action occurs at the desired time; "The good player times his swing so as to hit the ball squarely"

Another good one:

Time is a basic component of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify the motions of objects. ...

No, because most psuedo-random number generators use the current time as the seed for the random number set.

You are right if you are taking into account that he won't generate it in the exact nanosecond he initially generated it in. But if the parameters were exactly the same, the result will be, exactly the same.

Wait, what? So the "previous" day's events didn't happen, big deal. That can be used to your advantage quite a bit

IIRC most simple random number generators will spit out the same sequence of numbers when given the same seed. Most programs that need randomness will seed based on the current time when started up to prevent duplicate sequences like this.

But if you went back in time, assuming you didn't cause a new seed to be used (the same seed was used in both cases) then yes you'd get the same number.

If you talk about cryptographic random number generators, these usually have special safeguards in place to prevent duplicate number sequences because they are predictable, and thus insecure. But even still, it can't be completely random. Computers can only generate sequences of numbers that APPEAR random. So you would still get the same number... but you might have to generate it at the exact nanosecond you did before, for example. It depends on what factors the pseudo-random algorithm uses to generate a new number.

In conclusion:

Throwing out the concept of alternate dimensions, as long as everything happens exactly the same way it did before, you'll get the same number. Just don't change history!

quantum random number generators

You all bring up some good points

I've learned to avoid threads where people end up discussing time travel. The subject hurts my head as it is, hearing everyone else's opinions just makes things worse (especially when they're flawed in some way).

I recall the story of an online poker site that published its source code to prove the cards were being properly randomised. They seeded the RNG with the current time.

Some people synchronised their computers time with the server's time and got the same random number sequence and made quite a bit of money before the site caught on and changed their algorithm.

I forget what site it was or where I read about it.

Ask calvin to go back and time and try it

Yes with a but.

If the computer uses a source of entropy as the RNG you will get a different result. Traditional RNGs (including cryptographically secure RNGs) are PRNGs, which use a mathematical function to generate a pseudo-random number. These functions will return the same result if they are seeded with the same value.

PRNG seeds are typically derived from the system time or from an entropy source in certain cryptographic applications. The important part is that the PRNG is seeded only once, and then automatically seeded with the value the PRNG generates each time you request a random number.

If you start an application that was written properly, use it, then travel back in time to a point after you started the application, the result of the application will be identical.

On the first day of the general computer science class in college, the professor was going over different MATLAB functions. A lot of us were following along on our laptops, and when we all used the random number generator everyone got the same result. Everyone's random number generators were starting at the same point in the algorithm.