# How actually probable is to "meet" other people in No Man's Sky?

I know the game is not really multiplayer so I mean "meet" as in standing on the same point/Planet/System, even though there is no interaction involved. I thought the odds of this happening were really thin (from several interviews with the developer) but as it happens the other day I arrived at the same Planet/System my girlfriend discovered the day before. We made no effort for this to happen:

So, is this just a really odd phenomenon or the probabilities are not as thin as they made us believe in the first place?

Edit: So I'll add more data for clarification…

• We are effectively on the same planet, we just didn't log in simultaneously because we only have one gaming PC that we share. And I read this so I know we are not gonna be able to see/interact with each other and people seem to have no more interest in the "meeting each other" thing.
• We obviously knew each other beforehand and played about 1 or 2hs each every day since launch, with no effort or hope to meet each other.
• There are about 400,000 NMS PC players, according to steamspy.
• There are about 100 billion planets per galaxy, and we all start in the same one (out of ~18 quintillion planets total).

I can't figure the math but it seems like a really odd occurrence to even be mitigated by the Birthday Paradox.

Edit 2: So, to be even more clear, this is not a duplicate of "Is No Man's Sky actually multiplayer?". I've read that one very carefully and I understand that you can't see/interact with other players in it's current state. It's just the shared "Discoveries" feature that makes it "multiplayer".

I'm asking a different thing: the actual odds of running into the same Planet that another person is right now (again, even though you can only tell by the name/location), because every time Sean Murray got interviewed he stated that those odds are really, really low, close to none. Yet, I'm in the same planet as my girlfriend after only a couple hours of gameplay. So, my question being, which one is it? what are the real probabilities of this happening?

• Possible duplicate of Is No Man's Sky actually multiplayer? If your question is specifically about the maths, then perhaps your question needs clarification. Or you need to ask the good folks at math.stackexchange.com Aug 15, 2016 at 18:31
• @DavidYell I'm not purely interested in a math answer, I'm just really confused as to wether I should feel lucky about this or it's just plain common, since the devs says the possibility is nearly impossible yet people here claim it's "actually pretty high" (yet with no source). Which one is it? :/
– lima
Aug 15, 2016 at 19:24
• Also, why the downvotes? It's really puzzling.
– lima
Aug 15, 2016 at 19:25

The odds are actually pretty high that you will eventually "meet" somebody, as you can see. The odds of you being on the same planet at the same time and in the same place are where the odds drop like a rock unless you put in the effort and materials.

This is actually a version of the Birthday Paradox. With enough people involved the odds of two people having seen the same planet goes up VERY quickly.

• I should've clarified, that was the last planet she visited so if she just relogs we would be in the same planet. But we have one gaming PC and we share it so that's not doable. I've read about the Birthday Paradox applied here, but those odds are actually small enough for two random people to discover the same planet, let alone two people who knew each other beforehand in a 100 billion planets pool. I am no mathematician so I don't know the hard-data probability, but seems odd.
– lima
Aug 15, 2016 at 18:04
• The odds of you both knowing each other are lower. But if you are on the same computer there is probably something in the install that keeps your spawn points closer together than you would see on two different computers. Aug 15, 2016 at 18:18
• You as a player need something that determines where you start in the world called a "seed." It is possible that since you are using the same computer as your g.f that you are both sharing the same seed. This could potentially start you in very similar sectors of the universe/galaxy. It is all speculation though. I honestly don't know. Aug 15, 2016 at 18:24
• @fandelost The seed has to be generated locally, otherwise people playing offline would have nothing to explore. How that seed is determined is anyone's guess; however, there does seem to be a strong possibility that using the same device as another player will give you similar spawns. Aug 15, 2016 at 18:50
• @fandelost Steam requires you to be online in order to authenticate with their own servers (user validation and DRM and such). NMS does not require online connectivity to play, however. If you have the GoG version, you can play completely offline. Aug 15, 2016 at 20:09

On PS4, the 4th system I visited had already been discovered and named by another player. I sent him a message on PSN and he told me that the 2nd system he visited happened to be the 2nd system I had visited. (We were not previously acquainted.)

I have not read anything online about how frequently this is happening, but my suspicion is that the developers decided to make encounters more likely by deciding on a few million possible starting "areas" (i.e. clusters of 100-1000 stars) and then assigning each new player to one of those areas randomly. Either that or they badly screwed up their randomizer. :)

Note that in this case the birthday paradox is not too helpful; sure, the principle is the same, but 1/365 is a massive number compared to 1/18,000,000,000,000,000,000. Every time you place one birthdate on the calendar, you're taking away a sizeable chunk of the possible dates for other people. In No Man's Sky, on the other hand, you could place 10 million (or 100 million, or 1 billion) players on the map and not even notice them. It's like finding the probability of two among 30 people born at the same picosecond.

Now, the fact that players can travel around definitely makes meeting folks way more likely. But this early in the game it still seems weird to me. That's why I feel the developers must have manipulated the starting locations on purpose (or screwed up :).

::edit:: Ok, I missed one of your points about how we're apparently starting in a galaxy that's much much smaller than the total star count. I didn't know that, and if true then it changes the math quite a bit. If there are only 100 billion stars in the starting galaxy then the birthday paradox definitely begins to matter.