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A person is sent back in time 30 years to 1993 and they still have their phone. The phone is an iphone 11. It is on a contract. The battery is fully charged. The phone has a number of apps on it including the most popular social media apps and some local apps such as a step counter, camera, voice recorder. The person does not have a charger. They do not have access to a modem. They are in a very remote area but can travel to a large city (eg London).

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  • $\begingroup$ Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on Worldbuilding Meta, or in Worldbuilding Chat. Comments continuing discussion may be removed. $\endgroup$
    – L.Dutch
    Commented Apr 18, 2023 at 17:07
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    $\begingroup$ The phone would look exactly like it would if the phone did not have cell service today. (..... No Service), link below: google.com/… $\endgroup$ Commented Apr 19, 2023 at 20:27
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    $\begingroup$ To expand on @DevelopingDeveloper's comment, assuming you're talking about a UK-based mobile phone (you mentioned London) your immediate problem with using it as a phone is that it wouldn't have a recognizeable number; all UK mobile numbers changed in 1997 so the number on your modern phone wouldn't be recognized by any network, $\endgroup$
    – Spratty
    Commented Apr 20, 2023 at 10:19
  • $\begingroup$ You realize the processor alone on this outclasses the fastest supercomputer in existence in 1993 $\endgroup$
    – lupe
    Commented Apr 20, 2023 at 16:03
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    $\begingroup$ Oh, sure, but that's not the worst problem to solve $\endgroup$
    – lupe
    Commented Apr 20, 2023 at 16:06

13 Answers 13

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”What would the screen display be”

I’m going to assume you’re asking here about what would the display show on your phone, as in the OS it would display. If that’s the case, it would be the last version of iOS that the phone was updated to. (It’s important to note here that you won’t be able to update the phone OS version while you’re back in time, because obviously iOS doesn’t even exist yet). Any files stored on the phone’s built-in storage should still be accessible, and things that don’t require internet like the camera app, calculator, clock, etc. should definitely still work. I’m going to say that Social Media apps will likely not work, because all of the infrastructure they use hasn’t even been invented yet, so there’s no server host for the app to contact. It would still show the app, but it would likely give you an error message something like “failed to connect to server” for trying to use any functionality that uses internet connection. For a good real-world test for how the phone would function, assuming you have an iPhone since you include a specific model type, test its functionality with Airplane Mode on. Make sure that both Cellular and WiFi are toggled off (you can do this in control center by toggling on Airplane Mode, though I like to also toggle off Wifi and Cellular in Control Center as well). If you try this, it will give you a very accurate idea of what your character would be able to do.

“The Person does not have a charger”

Just to clarify, they can’t get a charger no matter what city they go to. The lightning cord that the iPhone 11 uses for charging has not been invented yet. Neither has QI wireless charging. So your person will not be able to recharge this phone. Now, if they have a bit of electrical skill, they could possibly make a wireless charger for the phone, or possibly even a plug, but the wireless charger would actually be far simpler mechanically to build provided the character has the knowledge required. Alternatively, maybe a tech savvy person from that time period could make a wireless charger or charging cord for it provided they know some basic things like voltage and amperage limits.

I hope this helps you out! If you have any other questions related to this, feel free to comment and ask, and I can try to provide more ideas and info.

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    $\begingroup$ @AvengingEarth Based on my research I think it could work. GSM was rolled out late 80’s early 90’s, and by 1993, 2G was common GSM standard. Modern phones like the iPhone 11 that support LTE can fall back on 2G networks when that’s the only service available. (There are still some rural areas in Europe and third-world countries where 2G is the only available signal). This would imply that it could actually possibly work for Emergency Calls, though I don’t think you’d be able to use data because you wouldn’t be recognized by a cell service provider. en.m.wikipedia.org/wiki/2G $\endgroup$
    – Kal Madda
    Commented Apr 17, 2023 at 16:24
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    $\begingroup$ @KalMadda Modern browsers can: if a webpage doesn't start with <!DOCTYPE html>, the browser interprets it in "Quirks mode" (i.e., emulating old browser bugs). Anything with Java or Flash is off the table, though; the iPhone was revolutionary in not bothering to implement any of that. Your bigger problem will be the non-existence of Wi-Fi (or even MMS!): there's practically no way to get data onto the phone. $\endgroup$
    – wizzwizz4
    Commented Apr 17, 2023 at 19:18
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    $\begingroup$ QI charging requires a wireless "handshake" between the 'phone and charger, which would presumably make the charger far harder to replicate in '93. The handshake is partly a safety feature to stop the charger heating up any metal object that comes within range, so I don't know for sure that a 'phone would refuse to charge from a simple coil, but it seems likely. $\endgroup$ Commented Apr 18, 2023 at 9:11
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    $\begingroup$ Forget about wireless charging. A simple 5V DC powersupply and connecting it to the 2 leads in the USB plug is all you need for a 200 mA wired charger (takes about 15 hours to fully charge). Add a couple of resistors will get you 1A charging which will be a LOT faster (about 3 hours). Of course you'll do need the schematic so you better have that stored on the phone itself and transfer that to a piece of paper before the battery runs out. $\endgroup$
    – Tonny
    Commented Apr 18, 2023 at 13:46
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    $\begingroup$ I'd want a citation that local emergency numbers were accessible from an otherwise non-authorized phone in the 1990's. Having universally accessible 911 service is (I think) very new and still not fully functional in some places in the USA: "... The FCC set a deadline for 'two-thirds of all cellphone calls to be transmitted to 9-1-1 dispatchers by 2002'... [but] the deadline was pushed back again and again..." pbs.org/independentlens/blog/… $\endgroup$ Commented Apr 18, 2023 at 18:14
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Forget apps.

It can turn on the torch

The bright white LED is a miracle of science in 1993.

It can take photos and videos

The digital camera is also sci fi in 1993.

It may have some offline maps

Turns out you know what roads, stadiums, etc, are going to be built where. Maybe only in your part of Pennsylvania/Zagreb/Wellington, but still.

It can play music and videos

Maybe someone has sent you a whatsapp video that you downloaded. Congrats, you have that video.

If you're really, really lucky, it has Ricky Martin or the Macarena or OK Computer and you have next year's biggest hit. Failing that, there's still ringtones..

It can store 64GB of data

I had to download DOOM (or was it Wolfenstein) over 4 successive nights on my dad's 4800 baud modem. The split zip files were 1MB each. I had to delete some other games. Too bad USB hasn't been invented yet.

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    $\begingroup$ Digital cameras in phones weren't around until just before the millennium, but they were sold as separate machines in the late 80s. $\endgroup$
    – wizzwizz4
    Commented Apr 17, 2023 at 19:30
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    $\begingroup$ In 1993, white LEDs weren't "miracle of science"-level. Blue and trichromatic LEDs had been commercially available since 1989, although modern excited-phosphor white LEDs were still three years from commercial availability. $\endgroup$
    – Mark
    Commented Apr 18, 2023 at 1:07
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    $\begingroup$ Right up until the battery dies... then there's no way to charge it. USB wasn't even invented until 1996 and the power protocol used by the iPhone 11 didn't exist until the 2000s. $\endgroup$
    – JBH
    Commented Apr 18, 2023 at 3:25
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    $\begingroup$ @JBH If he has a cable (not a charger, just a cable), it's easy to put +5VDC across the two power wires. With no cable, he may be able to take the battery out. $\endgroup$
    – user86462
    Commented Apr 18, 2023 at 7:09
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    $\begingroup$ "It can store 64GB of data" - how are you going to get data onto the phone, or off of the phone? You can take 64GB back with you (and that can potentially net you billions of dollars, if you put the right things on there), but once you are in the past, accessing that storage is going to be a huge issue for a layperson. $\endgroup$
    – NotThatGuy
    Commented Apr 18, 2023 at 12:14
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In the history of mobile phones, 1993 had GSM networks in Europe.

In the 1990s, the 'second generation' mobile phone systems emerged. Two systems competed for supremacy in the global market: the European developed GSM standard and the U.S. developed CDMA standard. These differed from the previous generation by using digital instead of analog transmission, and also fast out-of-band phone-to-network signaling.

The iphone11 seems to be capable of using GSM network

Is the iPhone 11 a GSM Phone?

Yes, the iPhone 11 model A2221 is a GSM phone, also known as the Global Version. GSM stands for Global System for Mobile Communications and is a digital mobile network that allows users to make calls, send texts and access the internet. This type of network is used in most countries arond the world. The iPhone 11 model A2221 operates on GSM networks, meaning it will work with most cellular providers.

Therefore, maybe calls and SMS would be possible. However, the operator will need to recognize the SIM trying to access its services.

There will be no other working apps, I am afraid.

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    – L.Dutch
    Commented Apr 20, 2023 at 14:51
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1993 is not the Middle Ages and you could do a lot with such a phone provided you find people geeky enough. If you dropped by my university (in France) I could point you to a few people.

If you are yourself a techie you will make their life much easier but even without that they will find out.

Charging the phone is the easiest. You would either tell them about the voltage, or they would try slowly from 0V both ways and finally got the threshold.

Communicating with the phone is more difficult but doable. It would take time to reverse engineer, though. (EDIT: see @Abion74 comment below. As I mentioned, I was looking at my Android phone when replying and missed out thee iPhone part)

  • There was no WiFi so bad luck here.
  • Ethernet over USB is conceivable if Ethernet is present (it was rather the time of 10Base5, but at least the standard was in place - so who knows)
  • Data transfer via USB would be fine

If you would consider upping the game by also bringing USB documentation with you, you would open the gates of sleepless nights for these guys and gals. It would be Christmas coming early for us.

You may also consider having an Android phone, which will be easier to work with.

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    $\begingroup$ Breaking news: mankind shrinking technology over night $\endgroup$
    – Clockwork
    Commented Apr 18, 2023 at 6:55
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    $\begingroup$ without an original ucb cable - good luck $\endgroup$ Commented Apr 18, 2023 at 16:28
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    $\begingroup$ Charging/data transfer would only be realistically possible if OP brought a USB-to-Lightning cable with them. USB 2.0 would be a fairly doable challenge to reverse-engineer for a good techie in 1993 (power definitely, and data transfer might be doable with some difficulty), but the Lightning connector has an encryption and authentication module in the head of the plug so good luck getting your geeks to ever replicate that. $\endgroup$
    – Abion47
    Commented Apr 18, 2023 at 16:30
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    $\begingroup$ Showing up with a recent model Android in 1993 might put Apple out of business if you could sell the tech to the right people. They were struggling before the first iPhone came out, which resulted in a huge resurgence in their popularity. If you managed to scoop them by over a decade at that critical point in their history, it could have devastating effects on their already hurting business. $\endgroup$ Commented Apr 19, 2023 at 13:27
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    $\begingroup$ @Clockwork "Breaking news: mankind shrinking technology over night " <- Back in the early 90s, tech was already shrinking so quickly that there is very little you could do that would actually amaze people more than was already happening. In fact, there were plenty of people who honestly believed that tech was only advancing as fast as it did because some alien or future tech had somehow been acquired, and movies like Terminator and Independence Day turned this into a common trope. $\endgroup$
    – Nosajimiki
    Commented Apr 19, 2023 at 16:51
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I don't think the other answer is correct. the iphone supports GSM which was launched in 1991, so at least in metropolitan areas in Europe and asia it will be able to make emergency voice calls. The united states did not adopt GSM until 1995 so this will not work here. Making a charger out of stuff available in 1993 is trivial. 5v power supplies are easily available, and a knife and wires would be enough to physically connect the power pins. This is enough to charge at 0.5A. Getting it to register to a gsm network of the time my be hard, unless you take a sim with a valid contract. Although a sim of the time may be cut to fit, all sims at this time used 5v signaling, and I'd be surprised if the iphone supports this. Modern sims support 5, 3.3 and 1.8v. Nevertheless, making electronics for this voltage shift is doable, though probably not fitting inside the sim slot. Anything available in airplane mode will also work.

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    $\begingroup$ Looking at other answers, the phone will operate as if it were in flight mode. Calls, even to emergency services in the UK are not possible under flight mode. But as the iphone 11 supports GSM you think that it would be able to make an emergency call? $\endgroup$ Commented Apr 17, 2023 at 15:25
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    $\begingroup$ @MichaelHarvey: OP specified in the question that it was an iPhone 11. $\endgroup$
    – Brian
    Commented Apr 17, 2023 at 20:28
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    $\begingroup$ @AvengingEarth there is no reason it ahould not make emergency calls. Gettiing a sim to work will be hard, and as for gsm data suggeated in one of the answers forget it. gsm data is a data call, ro modem at the other end $\endgroup$
    – camelccc
    Commented Apr 17, 2023 at 23:42
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    $\begingroup$ GSM has changed over the years along with cell technology. The fact that the iPhone 11 supports GSM in 2023 does not mean it's compatible with GSM in 1993. Getting this phone to be recongnized on a 1993 cell network would indeed be miraculous. $\endgroup$
    – JBH
    Commented Apr 18, 2023 at 3:27
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    $\begingroup$ @Joooeey no he cant. All sims prior to 1998 use 5V signaling. All phones manufactured much after about 2000 use 3.3 or 1.8v signaling. 1,8V sims support 3.3 and 5V so will work in an old phone, but a 5V sim can't operate with a 1.8V supply. IF you can get around the 1.8V 5V issue, the protocol is I think the same, but this is a rather big ask. As for using the internal sim, Europe never supported this, and the USA didn't use GSM at all until 1995. this voltage conversion is going to be a pain since 1.8V logic chips came later, so you would have to build a circuit of transistors or something. $\endgroup$
    – camelccc
    Commented Apr 18, 2023 at 12:20
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Who are you showing your phone to in 1993?

Suppose I worked for Sony. The had made the standard CRT video monitors for years. LCDs were not going to challenge them for dynamic range for another 15 years. If I were to see the display, I would want you to turn it off immediately. I would then arrange a microscope / spectrometer to get as much information as I could. You could tell me it was an OLED. I would know what an LED was, but the blue ones had not happened yet. We had not yet got to the point where CRTs would have rivals, but it would surely come. There was also a firm belief that semiconductor resolution was limited by the wavelength of near-visible light. But, once you are shown that the firm limits were not so firm, you can start thinking of alternatives.

When I was born, there were perhaps 48 Kbits of memory in the whole world, and 12 Kbits were in ENIAC. I remember clock speeds first going above 100 KHz, then 1 MHz. It is a huge leap of faith to make the first atom bomb, or the first hydrogen bomb. But when someone else has done it, and you know it is possible, figuring out how it might have been done is easier...

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    $\begingroup$ Blue LEDs were invented in 1989, and available commercially in 1993. $\endgroup$
    – Karl
    Commented Apr 18, 2023 at 6:16
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    $\begingroup$ and those guys at Sony would know very well that reverse engineering an integrated circuit like that isn't going to happen. They could get SOME information by taking x-ray photos of it, but that doesn't show the doping and other materials used. $\endgroup$
    – jwenting
    Commented Apr 18, 2023 at 7:01
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    $\begingroup$ Color LCD screens were already on the market in 1993. The passive-matrix Powerbook 165c came out Feb 1993 and the active-matrix Powerbook 180c came out in June 1993. The backlights were electroluminescent. They would not have been regarded as "magic" in 1993. $\endgroup$
    – DrSheldon
    Commented Apr 18, 2023 at 10:41
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    $\begingroup$ Yes, but they had a poor contrast ratio. We could not use them for film grading in 2010. The contrast ratio of an OLED screen would have beaten CRTs back then. $\endgroup$ Commented Apr 18, 2023 at 15:31
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    $\begingroup$ @RichardKirk 1989 saw the invention of the blue GaN LED, Nobel prize 2014. The SiC version is older, but never worked really well. Was it even commercialised? $\endgroup$
    – Karl
    Commented Apr 18, 2023 at 21:20
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Flip your phone to airplane mode.

Boom. You are in 1993.

By doing so, you just turned off the cellular data modem, WiFi and Bluetooth connectivity to other things, which are the key to everything that makes a phone a phone and not an iPod Touch, and none of which exist in 1993.

Whatever still works on the phone, will work in 1993. You can (at the risk of this turning into "how to use a phone"):

  • browse emails you already downloaded, but no new ones will come in
  • use files that are locally downloaded on the device (cloud will be unavailable) — use apps like notes and calendar that are able to work offline despite being unable to sync.
  • watch/listen to media in local phone storage, but not media "on the cloud"
  • play games that don't need to bang a server for anything

You can give social media apps and always-connected games like Diablo or Pokemon:GO a try, but you'll find they complain about "no internet" and that's that. If 10 of you brought your phones, Facebook and Tiktok will not work among you because the server infrastructure is not there.

The phone will not know what date it is, because the cellular data network and internet it gets the time from are not there. Speaking of that,

GPS will be extremely slow and less reliable, because phones use augmented GPS, which improves reach in complex geography and greatly speeds up GPS fixes, but reqires the cell towers be involved. Old GSM towers aren't set up for augmented GPS. GPS on phones (and embedding that in 911/112 calls) is a long, long way off.

Recharge

If you did not bring your charging block, the phone will deplete completely in 12-24 hours because every minute it is trying every generation of cellular it is capable of, notching up transmission power to max to try to reach a tower. If you have the foresight to switch to Airplane Mode almost immediately, you may get a week or two of standby time out of it, minus usage of course.

Supplying 5V to the port is simple enough, the problem is coming up with a workable substitute for the advanced USB-C or Tesla - I mean Lightning connector.

If you went to a competent lab and said "I know I can charge this by applying 5V to two pins of this heretofore undeveloped connector", they could probably X-ray it and figure out which pins from trace thickness and PCB markings. Disassembling a modern phone non-destructively is a PITA unless you know the tricks.

5V or 3.3V would be an easy guess, since PCs of that age are already using that. Any PC power supply will give you the 5V. So you could eventually develop a charging cord that goes "PC keyboard port to Lightning" with a T-connector so the keyboard could still be connected.

At that point you would get basic boring USB charging at 0.5 to 2.5 watts. No fast charge because no handshake.

But GSM, though

Maybe you could make that work. But you'd only get talk and TXT, they aren't really doing data over GSM yet, but it doesn't really matter. First, the system is not designed for the volume of data the phone would ordinarily use, and second, literally zero of the servers it would talk to are there yet. Most likely the Internet connection would be saturated by the phone's ordinary housekeeping traffic, and the carrier would get mad and turn it off. Also, GSM takes unbelievable amounts of battery power compared to G5; they've been shrinking battery sizes accordingly and the result is much shorter runtime when on older networks.

Also, if you hadn't already installed a telnet/ssh app, you won't even be connecting to MELVYL or Compuserve, or a shell provider like Netcom or WELL. That was how you did the Internet then. Hope you enjoy command line lol.

Here's a twist, though: if you can get someone to support Internet data on GSM, email will work. It should be able to talk to POP and SMTP servers of that age. Unbelievable. And that would be compatible with the constrictive data limits of GSM, since people weren't exactly mailing videos then.

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  • $\begingroup$ I'm pretty sure you are wrong about GPS. Augmented GPS is used to speed up GPS lock but if you want to get a lock without a cell phone connection / wifi connection to assist you, you just need to wait 5-15 minutes to get it. $\endgroup$ Commented Apr 20, 2023 at 8:46
  • $\begingroup$ NTS was around long before 1993. $\endgroup$
    – fdomn-m
    Commented Apr 20, 2023 at 9:58
  • $\begingroup$ I'm really curious now: What would it take to get GSM to work beyond emergency calls? $\endgroup$
    – Joooeey
    Commented Apr 20, 2023 at 11:25
  • $\begingroup$ @Joooeey you will need a valid simcard of an active services provider. And I am not sure if simcards back then will be compatible with the current technology. $\endgroup$ Commented Apr 20, 2023 at 12:24
  • $\begingroup$ I think AGPS essentially uses the internet to download a file saying where the GPS satellites are today. It's not some passive listening thing. There is a passive listening thing though - the GPS satellites themselves are constantly broadcasting this data... very slowly. It takes 12.5 minutes to get a whole copy. 25 minutes if you missed some the first time, which is why we prefer to get it from the internet. $\endgroup$ Commented Apr 20, 2023 at 12:25
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To me, it sounds like you would pretty much have a pocket-sized fancy calculator/computer that can also play music and media stored on the phone, and has a working torch, a camera, a voice recorder, and can play games! It would impress the hell out of anyone encountering it. It would look (and be) superior to the Game Boy, the Walkman, Cd Players, portable TVs, etc.

But I don't think it would function as a phone as it would not be compatible with the networks of the time. Maybe if you took it to a research university and explained what it was, then maybe someone could figure out ways to make it work. But it's a big maybe.

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Also consider that if the phone can't find a cell to successfully connect to, it will turn up the transmit power and "yell harder" in case its just out of range.

The phone will use up the battery's store of power much quicker than normal. If the phone lasts 24 hours of "normal" usage you might expect it to be flat in half that time.

This could be a plot point where the device turns off unexpectedly at a critical moment.


In airplane mode, the battery lasts a lot longer. However the time-traveller would have to remember to change into this mode, and it may or may not allow GPS reception still.

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    $\begingroup$ In airplane mode, the battery lasts a lot longer. $\endgroup$
    – Karl
    Commented Apr 18, 2023 at 6:18
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    $\begingroup$ @Karl Excellent point - added. $\endgroup$
    – Criggie
    Commented Apr 18, 2023 at 6:55
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    $\begingroup$ You can activate GPS separately, but it's also quite energy-hungry. $\endgroup$
    – Karl
    Commented Apr 19, 2023 at 18:00
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At first you won't be able to read any emails. But with some work you could read everyone's

The iphone 11 comfortably outclasses the largest supercomputer of the era, at about 6 times faster (690GFlops, vs 100Gflops). In addition, the NSA had mandated a relatively low strength encryption standard (DES 56), which would later be trivially cracked. You can break into pretty much anything. Of course, you'd need to be decent at computing, but once you're there, the world is pretty much your oyster. Try and make sure you download the wikipedia article on the dotcom bubble before you go.

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If you're in a major city, finding an electronic repair store like Radio Shack might be able to rig you up a rudimentary charger. They'd likely charge an arm and a leg, but it'd be doable; especially if you have a replaceable battery that lists its information.

Lucky for you, the full first constellation of GPS for the US military finished in 1993, and this is a send-only system. In other words, your phone would still pick up GPS (that said, government might have significant interest if they got whiff as you used it, because the first public use didn't come till later).

Between these two, you could get an instant job aboard any public seaship of the era.

Social media apps are mostly toast. Your only use from them will be some cached article headlines and messages. The former could be useful for knowing a handful of future events.

If you have local storage for your email, this could be a treasure trove of knowledge on the times of various major events, and guide predicting some things a bit more precisely than your memory.

Wireless calling:

1G and 2G actually existed in some cities at this time, but since your sim card is likely to an account that doesn't exist (and sim cards don't exist yet so you can't replace it). You'll be limited to 911 calls. This could be useful for emergency response, but that's about it. It could be a lifesaver though.

Cameras and Voice recorders of various kinds existed in this time, but they were big and bulky. Might be good for spy work since noone would expect.

The biggest benefit is going to happen if you're running Android and can get a Serial-to-serial connect juryrigged (doable, but a pain - again, a lot of time in radio shack - USB [Universal Serial Bus] is a descendant of older Serial Bus standards, and is surprisingly still backwards compatible - for example, I have a USB-to-Serial cable for my older printer - matchup could pretty much be figured out with a multimeter). Android is open source and Linux-based, and Linux already exists in this era, which means if you can get at the code, there may be chunks that could jump waaayyyy ahead in computer software development. Being closed source though, an iPhone will provide no benefit, as there's little to no chance that any of the code will be accessible. If the time traveller is a cell phone firmware developer, this will be the best bet to maximize use of the cellphone.

This last one is huge, because with that tech, because Linux relies on a small kernal that can still be installed on 90's computers today. You could crush Microsoft & Apple and prevent the rise of Google. The OS code syntaxes would reveal ARM architecture, so you could also overpower AMD and Intel. Now, they won't be able to replicate the chips themselves, because modern boards use chemical pressing techniques that weren't nearly as precise back then - that march of time will still have to repeat because that precision came from better computers & sensors which allowed better precision tools which allowed better computers & sensors, etc, and the sensors on a cellphone aren't nearly the quality used for production & develoment. (Though your phone's processing capabilities may be able to bump them forward a few years - or a lot of other industries for that matter - it's basically a handheld supercomputer for the time).

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What you couldn't do

Charge the phone The USB standard hasn't been invented yet so you can't charge it via micro-USB or USB-C

Transfer files to the phone The phone either connects via USB or by reading the micro-sd card (if it has one). Neither of those exist in '93.

Call someone The operators in '93 wouldn't be able to recognize the standard the SIM card in your phone uses.

Access the internet Both mobile data or wifi and both are non-existant at this time in history.

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    $\begingroup$ Charging would be much easier with a different brand of phone. Foe example, many modern Android phones still have a removable battery, so you can use any laboratory power supply with an amperage limit to charge it. $\endgroup$
    – vsz
    Commented Apr 18, 2023 at 19:40
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    $\begingroup$ @vsz every battery is removable if you have a screwdriver and soldering iron $\endgroup$ Commented Apr 19, 2023 at 10:35
  • $\begingroup$ Although the micro-SD form factor didn't exist in 1993, you can trivially create a electrical connector with pogo-pins and talk to in using the SPI protocol, which dates from the 1970s. You'd then have to work out what commands to send via the protocol, but it would be doable. $\endgroup$ Commented Apr 19, 2023 at 11:19
  • $\begingroup$ also lithium batteries were rarer in 1993, but still around. I'm sure any laboratory would have no problem getting their hands on a suitable charger. $\endgroup$ Commented Apr 20, 2023 at 12:30
  • $\begingroup$ @user253751 : or you charge the battery manually, with a current-limited power supply, and carefully monitor it yourself, disconnecting it before it goes too close to 4.2 Volts. That should be possible even with common laboratory equipment from over a hundred years ago. $\endgroup$
    – vsz
    Commented Apr 21, 2023 at 20:00
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Difficult to say without testing but the Lightning connector (wiring of that can be found here) has one pin for power (pin 5) and another for the ground (pin 1). Unless Apple has done something to require the digital communication, a good laboratory of the time may be able to make a custom connector to charge device. It is not that miniature:

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I think that a good laboratory of 1993 should be capable of making this connector (image credit). This can be done, for instance, by etching the narrow printed circuit board (technology appeared in about 1956). Mind that only two contact plates need to be drawn to implement the charger, not all 8.

Being able to charge opens more scenarios for prolonged usage, unless you need a tension for your story with the battery running out.

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  • $\begingroup$ The connector is not needed if you dismantle the phone and solder to the wiring inside. Or if the time traveller luckily brought a Lightning cable with them (not necessarily a charging cable) $\endgroup$ Commented Apr 20, 2023 at 12:31
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    $\begingroup$ @user253751 The problem is, a user unfamiliar with all the iFixIt.com tricks required to get into a phone, is all but guaranteed to smash the glass trying. That's the digitizer, so game over. Far safer course would be to X-ray it and look at the PCB. If there's no handshake and just +5V on the port, the phone should charge at a limited speed. $\endgroup$ Commented Apr 20, 2023 at 19:22

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