What time is it?

Buy a newspaper when you get there.

use an ATM time and date stamped on the receipt

Buy a news paper and ask some one the time.

That's so unusually short sighted of you. If I travel more than a few hundred years in either direction, there won't be any newspapers, and I won't be able to speak the current language.

Sure - maybe if you went back 1000 years you could squeak by with saxon swear words - but for me 1000 years past means karankawa indians -The "savages" would lash a captive to a stake and, dancing around the stake, they would dart in, slice off a piece of flesh with a sharp blade, then roast it in front of the victim, in an already prepared campfire. Then they would devour it, as the victim watched his own consumption.

And if I go 1000 years into the future, everyone will be speaking Chinese or French or something equally difficult, and I'd probably still get eaten.

You said....

(Assume that I've got a typical university library and lab facilities available to me.)

So, walk in, walk up to the nearest computer and look at the lower right hand corner, date and time right there, and NO KARANDAWA INDIANS, unless they had a typical university library and lab facilities available

I'm not explaining myself very well.

Assume that I, while playing around with the tokamak at my local university, transport myself, and the university, through time.

All the clocks are still in sync with my previous time, there is no Internet connection, and no one is around who can express the date to me in anyway that I can understand.

How can I, using the wealth of knowledge and equipment available to me, determine where I am in time (before the Indians, and/or French, eat me.)

"How can I, using the wealth of knowledge and equipment available to me, determine where I am in time (before the Indians, and/or French, eat me.)"

Sounds like it is simply dinner time.

<...All the clocks are still in sync with my previous time, there is no Internet connection, and no one is around who can express the date to me in anyway that I can understand...>

Then why does it matter? All time and date is simply a protocol. Were it not 2008AD according to the Gregorian Calendar then it would be something else according to some other protocol.

What percentage of CR4 readers can read Hebrew (rhetorical question for illustrative purposes)?

Check out a book and run home to see if you received an overdue notice in the mail.

I don't think a 1000 years in the past you would have a conventional lab available to you or a library. So we were assuming you didn't go back that far in time.

If you did go back 1000 years try acting crazy.

Woo. Getting down to the day is usually tricky.

Stars are generally the way to go, but even then it's hard to tell with precision. And really once you go back past about 10 million years fine-tuning kind of gets pointless. A day is a day is a day. Except when it's night of course.

One rough way of at least getting ballpark is to take a carefully measured lump of something suitably radioactive with you into the past, leave it where you think you can find it, then move into the future to a known date and retrieve the lump. Study how much it has decayed. Not the best method, but it works when you don't have time (no pun intended) to fiddle with stargazing.

Now every one let's help this person out. Before you plan the trip be sure you check the position of the earth. You will need to know where it is at. If you travel 24 hrs in the future or 24 years you will need to make sure you have a place to land, there is more than forward and back during time travel. There is a where. Remember you and your device is the only thing traveling in time everything else is stating where you left it. So during the calculations of where the earth will be say in 90 days, you will be very aware of the when. Thanks to Issac Asimov for the true math behind time travel.

I'm invoking Hollywood Rules in this time travel endeavor.

Then you have my creative permission. So I would just sync the Prius time clock with the travel circuit. I am sure with gas prices going the way they are you will need to conserve fuel for the return trip, so save the Delorean for the weekend trips!

Your tag line has been made famous by Stewie Griffith.

A Prius? How is that possible? I thought you had to reach at least 70 mph.

Well ,we have to adjust for performance, emission controls and fuel economy. The Delorean can get up to 88mph easy. The Flux capacitor will have to be flux-e-er.

Most things can get up to 88mph quite easily.

As long as the cliff is high enough

Roll with it then for sure...

Well, I guess if you envoke Hollywood rules you would already know the date and the time because it would be right there on the dash board of your deLorean. Wouldn't it?..... Hello, Mcfly

That's a good one: the moon is getting further away by so-many-millimetres per day.

There is a limit on how far you can go back in time to measure the distance to the moon.

The laser reflector on the moon was placed in 1969 by Apollo 11, so travelling further back than '69 the ranging measurements are more difficult/inaccurate..

beam through an optical telescope," Dickey said. "The beam enters the telescope where the eye piece would be, and the transmitted beam is expanded to become the diameter of the main mirror, then bounced off the surface toward the reflector on the Moon."

The reflectors are too small to be seen from Earth, so even when the beam is precisely aligned in the telescope, actually hitting a lunar retroreflector array is technically challenging. At the Moon's surface the beam is roughly four miles wide. Scientists liken the task of aiming the beam to using a rifle to hit a moving dime two miles away.

Once the laser beam hits a reflector, scientists at the ranging observatories use extremely sensitive filtering and amplification equipment to detect the return signal, which is far too weak to be seen with the human eye. Even under good atmospheric viewing conditions, only one photon is received every few seconds.

Measurements show that the Moon is receding from Earth at a rate of about 3.8 centimeters per year

So, how many labs have this equipment?

Most labs have the internet and almost all have a clock.

Next, look in the trash cans for dated materials.

Stay away from your grandfather.

If you just want to get close the cancellation date on a first class letter at the nearest mail box.

I would make sure I arrived in England! It nearly always rains at the weekend so you wait for the first rain and call that Saturday! You could also work out the time of year by the height of the sun or the length of the day. As for what year! Find an ice mass near a pole and take a core sample! Look for signs of the industrial revolution or large volcanic eruptions at a know time and 'count the rings'!

Do to the effects that mankind has had on the world the poles have melted.

Hello bhankiii

Presumably you have travelled backwards in time in a "Time Machine".

The designer of that "time Machine" would certainly have included a clock as part of that "Time Machine", which went either way, depending on travel direction.

Look at the on-board clock.

Kind Regards....

Though the TIME is a dimension in universe, scaling of time is man made. Thus, when nothing is available to refer to your original time frame, you start your own time count. Year 0000 Month 1 Hr 00, M 00, S 00.

May be you can wait for midnight to start this count.

Forwards in time, you had better pack your sunscreen and sunglasses

and get out of the building before your caught, they'll not take too wisely you steeling the building and returning it 1000 years in the future, also causing the deaths of those you land on.

1000 years in the past? take gold, blankets and cheap jewelery and start buying as much land off the indians as you can, jump back forwards, and make a killing with people building on your land (back rent)

Heck my computer has the time on it at the bottom of the screen. Place the cursor over it it will give you the date. Who needs to look up the star charts.

cause as you jump forward or back in time, your computer clock that is running in sync with the battery backed RTC will retain the time in the zone your in.

The computer would have to connect to a NTP server to get the updated and corrected time, usually pool.ntp.org (I don't trust Windows as it is, I wouldn't rely on their time servers either.

the observable stars would be outside your frame of referance when you travel forward or back in time, so the star charting proggy would be useful, I have Starry night installed on my system. If it can connect to the external Internet to update, it will update your computer time too.

Assuming you're on earth, you can use radioactive decay - eg find a bit of uranium - the ratio of U238 and U235 (currently 99.3 : 0.7) will give you a clue. The more U235 you detect the further back in time you have gone (2 billion years ago the ratio was more like 97 : 3).

This won't tell you if it's your birthday or not, but you'll get a bit of an idea.

Be on the lookout for astronomical events - eg Halley's comet would tell you to the day (but you wouldn't know which of the 76 year cycles). However if you could get a fix on a second known comet then you could work out the relationship between them to get the exact year. (Also the existence or not of known supernova might help.)

Someone mentioned core samples - these might be your best bet for the past - just make sure you have the data on board, take an air sample when you arrive and compare it to the tables - you ought to be able to predict within a few months that way, at least back a few hundred thousand years.

The future is harder, however presumably you could leave something testable in a safe place and pick it up when you arrive...

Grab me a few microsoft stocks if you happen to swing by the 1980s.

Let us not for get in the calculations to put in leap year. While we can check the heavens for there perfect position , us petty humans will need to observe the leap year to keep things straight. That said,

I would off hand suggest a TOC count (total organic carbon) however you would need a base line and organic compounds regenerate, so If going by Hollywood rules and there is a working lab, I would before departure place some type of ore weather it be iron or the powerful u23* series under the lab so as when you re materialized back to the same spot you could extract it. I would use Xray diffused scattering measurement on the atomic level and check the degradation of the material. then plug in my every four year leap. Yes that promotes more questions and thought but ain't that what this is about. And I did say "ain't".

You have a library in your future time, and the library will have either newspapers or on-line daily news that is dated.

I has been suggested using Pulsars as an universal clocks for intergalatic travelers. Pulsars have a highly accurate spin which is slowly changing over time. The rate of change is very predictable. The amount of change in Pulsar spin could be used to find change in time.

Tell a mean-looking woman that it must be Friday the 13th, 2130, and that meeting her is enough proof for you. Right before she punches you in the nose, you should hear her tell you what the correct day and year it is, after, of course, a few expletives.

Plot the location of Polaris vs magnetic north. In a few thousand years Polaris will no longer be "the north star" due to the movement of the magnetic north and the shifting of the night sky. I'm sure with an accurate sextant and some research you could estimate the year to within a century.

Following this, I would next look to the position of the planets. The specific locations of Mars, Saturn, Jupiter, Venus and Mercury should then give you a date almost to the exact day.

I understand that Polaris will be right on in 2017, and it changes 50.3 arc seconds per year.

You guys are way over thinking this one. If i go to the future/past, the first thing I want is a really hot babe, preferably European.

I will impress her with my knowledge of the future/past. We will live happily ever after, not caring of the date or time.

We will live happily ever after,

you will live happily, till you jump to some other time in search of new babe>

Good one, Then she will be smart enough to ASK someone what the date and time is!

Thought I have on time travel is that if you make a jump in July (for example) to December, the Earth is going to be on the far side of the sun when you come out, and there will be nothing around except lots of vacuum. How might we handle this??

Bill

See post #7

Frames of reference! (Think about it).

Life, even in time travel, is full of risk and consequence.

In that case, in your last 15 seconds, you might:

(1) ponder your life, your successes and failures

(2) try to remember if you shut off the water in your bathtub before you left

(3) calculate the exact time and date (wait, no time)

(4) search frantically for the "send me back quickly", button on the time machine (otherwise labeled as "OOPS!")

(5) scream ... remember, you've only got one, and no one will hear you anyway

(6) get really upset that Scotty forgot to calibrate the transporter

(7) wonder why this never happened in the movies

(8) ponder how many eons it will be before some passing spacecraft finds you as debris ... and uses you for target practice

(9) assume the crash position ... place your head between your knees ... and kiss your arse goodbye

Hello, bhankiii

If I were you being owner the Time Machine I rather came back in time moment when prices were pretty good just for nice shopping, maybe couple of canisters to get cheap petrol. I'm scaring the most of people would find out this kind of TM's using more preferable. BTW any supermarket receipt cheque contains full data and time records printed out for consumer.

Also here is some bad scenario's developing when time traveler might be caught the authorities (police) for ...umm.. for instance, possessing of fake dollars! It's so bad! The only soothe for you is to be informed in details about just what you've been interesting at your post: i.e. exact location, date, time and something else concerning your crime activity. They should represent this at filled police protocol during investigation.

Isn't it a time to be concerned asking anyone consumer looking strange: "What time is it? What year and date is it right now, sir/madam?" Or even: "What time are you from?" in order to cope with galloping inflation.

if happened you appeared in former Soviet Union I would advice you urgently to throw out all your stuff, dollars, laptop, canisters, optic instruments include and be pretended to be as a dumb person. In case of 197s-8s I could offer you my old phone number in hope I was a smart boy who adored Sci Fiction. So here is a great chance I would believe at your story and help you to get US embassy. Although, I am not sure about yours ambassador response .

If you get stuck in ancient time. There are two self exclude chances: you're staying a god for tribe people or...... In any case question: "Where is a nearest library here?" wouldn't be the best choice for you. Pretending to be a dumb person --- would be best kind of behavior here as well.

happy time journey, caramba

P.S. Do you bring up your pet to be your defender for such a risky adventure?

You could just ask your friendly time lord for directions!

Charles

Who are you talking about?

OK, smarty... What is Dr. Who's real name?

In the story where they were on the ship that accidentally created our Universe, where the people with Lasser's disease were being treated, the Dr. runs into an old school chum that remembers him and calls him by his real name.

OK Vermin I'll bite.

which Doctor Who are you talking about?

I have a few ideas David Tennant as the tenth doctor; or Colin Baker as the Sixth doctor;or Sylvester McCoy as the seventh doctor.

As much as I like the Doctor Who series late 70's to early 80's and the past few years

on Scifi channel and BBC American. There is a lot of the Doctor Who universe I have not had a chance to explore. I have listen to some of the audio stories and read a few of the books.

So enlighten me please?

Charles

That would be the infamous Tom Baker!

Again, I think your right! And your memory is a little better than mine!!!

In the episode I'm talking about, the Dr is played by the guy wearing the cricket outfit. And the Dr's first name is PHI (like the Greek symbol). Can't remember his last name, though. Shows you how much I know.

Hello Vermin,

I believe that was Colin Baker as the Sixth doctor.

Charles

ps I agree with Tom Baker Doctor number 5.

That was who I had though of first, 'should have included in my list' but did not.

Thanks Anonymous Hero

Yeah, but Tom Baker was the coolest doctor! Did you know that Tom Baker and the little, blond Ramona were married (in real life) for a time. So at least he got to b#*g the little vixen!!!

That was from the last of the Key to Time episodes. Romana I meets Romana II (as Astra) in the Armageddon Factor. Drax was his old school buddy. I don't know the spelling of his (the Doctor's) name, but it sounded like Fief.

Very good!!!

Why not just check your GPS?

There is a school of thought developing that the human brain can "see" 7-15 seconds into the future anyway, thereby avoiding the worst of threatening events by instinct. If so, then why do so many people make a mess of The Weakest Link? And have road accidents, come to think of it?

Good morning PWS

I think Mr. Adams understood .

Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so.
-Douglas Adams

Oh s#*t!!! That truck is heading right fo........

I could tell you. But then I'd have to kill you.

Either that or induct us into your "He-Man Woman Haters" club...

<...Any other ideas?...>

Radio-carbon dating.

Lets assume you're in the northern hemisphere. I think your first step is to figure out the "North Star" of the time. Simply watch the sky for a night and see the point about which the other stars rotate around (roughly), this is your north star (or more likely your "North No Star". Due to precession, the north star changes. One cycle of precession lasts about 26,000 years.

I'm going to assume you at least know within 20,000 years what year it is, this is an Engineering Forum after all, some precision is expected.

So lets say that the above procedure gets you within roughly 500 years of your current year.

With that knowledge, as someone suggested earlier, use the respective planetary positions to determine the year. Higher precision may be possible using planetary alignments, but lets assume less precision, so now you've narrowed it down to the year.

Now to narrow things down further, use the spot you've identified in the sky as the north star/spot and calculate your latitude (do this by measuring the angle above the horizon that your north star/spot is in the sky above the horizon. If you're at the equator this angle is 0 degrees. At the north pole its 90 degrees. Yours will be somewhere in-between. (It's worth noting this procedure works equally well in the south, I just had to pick a hemisphere for the example).

Now that you know your latitude, measure the length of your day. This will tell you what day of the year it is within a few days or so. Build a sun dial to then know roughly what hour it is.

That's the rough approach. No real special tools needed. Just a book of planetary positions and a book of sunrises and sunsets.

Log on to CR4 and see how many responses Kris has had to the 'breaking a cast iron bath' thread?

Here is something that I always wonder about when it comes to time travel: Say you go back a hundred years. Pick a date, any date. Go back to that time. Now, when it is time to come forward in time, how do you ensure that the future that you are coming back to is actually the "now" that you left in the first place? I mean, isn't the future always in motion? What if something different happens during that century that you traveled through that never happened originally? Say, Pearl Harbor never happened, or the A bomb was never developed, the Nazi's developed the tech (and used it) to deliver the V2's love child(you know the one that could reach out to the east coast of our country) and then used it, the baby boom never happened what ever the scenario. The "future" would be changed in some way or another right? Would you even exist? The idea of time travel has always perplexed me for this reason.

Actually, most time-travel novels and movies use that paradox as a popular theme. One typical one was "The Sound of Thunder", which, although I didn't agree with the 'time waves' approach, did focus on tiny changes making huge changes in the future.

In my own opinion, what we know as reality is actually an infinite number of possibilities, one of which we happen to be 'in'. Like a chess game, each move has several 'next moves', and each of those several 'next moves', and so forth. Therefore, whatever we deem to be the 'future' isn't yet written ... at least there is not just 'one' future, but many.

Again, in my own theory, we can go back in our own timeline to our own version of the past, but going forward poses some interesting paradoxes, because from that past, then viewer's 'now', there are again many 'futures'.

One better way of looking at time travel may be to consider traveling 'between' these 'possibilities' of reality (also, very popularized in novels and books ... former TV series, "Sliders"). If we had choice over that travel, we could 'control' our destination ... then again, we would probably go totally NUTS seeing all the possibilities. (maybe THAT'S my problem )

One way we can KNOW that time travel will never happen, at least not as we are considering it in this thread ... is because it hasn't happened ... at least not in OUR timeline .

Take care ...