# Would a giant see our year as a second? [closed]

If there were an enormous being whose arm span is one light year across, how would that being perceive time? Wouldn't what we perceive as a year be virtually nothing to that being?

Explanation: "sintetico" had it right when he or she suggested that the question is about the perception of time.

The question is basically, "Does our size, and how we relate to distance (or length of time since they are relatively the same) define our perception of it?" And I asked, "part 2," because I have no scientific background. This is just something I feel, and so I also feel that some of you WITH adequate knowledge could instantly tell me I have a very poor and incorrect concept of relativity. But so, to explain my possibly idiotic thought process further:

When I see the light from a star 1 light year away, I'm seeing what happened 1 light year ago, but ALSO I'm seeing what happened "9.46 trillion km ago." Right? "Space-time." But so, regardless of the obvious fact that a being this large would have mass that would create an enormous black hole, let's just ask, if he COULD exist, how would he perceive a light year? He can see all of the light (and events) in what we refer to as a light-year, simultaneously, all of it in his immediate reach. To him, the distance we see as a year, or 9.46 trillion kilometers, is virtually nothing, so since that "year" to us can all be seen immediately by him, is our year for him merely an instant?

Hell, now I don't even know if I fully understand what I'm asking. I guess I'm hoping one of you can tell me where I'm confused.

Thanks for your time.

• Even for the tiny ant, one second is one second; so for a giant also, one second would be one second. Time interval doesn't change for varying bodies, no matter how large or small it may be:/ – user36790 Jul 14 '15 at 4:09
• I think the question is clearly asking about the "perception" of time, and not the time itself. In this sense the question is meaningful and I don't think it deserves downvoting – sintetico Jul 14 '15 at 9:02
• This question is all speculation. I'm voting to close it as primarily opinion-based – Jim Jul 14 '15 at 13:08
• I'm voting to close this question as off-topic because you are asking an open-ended, hypothetical question: “What if ______ happened?”. – ACuriousMind Jul 14 '15 at 14:07

## 3 Answers

If there were an enormous being whose arm span is one light year across, how would that being perceive time? Wouldn't what we perceive as a year be virtually nothing to that being?

It would probably have to have decenteralized brains spread throughout its volume here and there. Otherwise, yes, there is a distinct problem that a being with a single large brain wouldn't be able to form many judgements per unit of time (assuming that, at minimum a judgement must take in information from all regions of the brain -- note that if this isn't the case, we're back to decenteralized brains).

• FYI I edited the question, in case you'd like to edit your answer accordingly. – David Z Jul 14 '15 at 6:59

A being with 1 lightyear arms or even 1 lightyear across and density similar to flesh would be sufficiently dense to create an enormous black hole. Even planet sized, a being of that size runs into gravity problems, where, lifting it's arm would require significant energy to resist it's on gravitational attraction on it's limbs, so too big doesn't work. But say, really really big. Improbably big, like a two thousand foot tall elephant like animal (low gravity planet, thick atmosphere - who knows). Would it experience time more slowly, or even on an earthly scale, do Elephants experience time more slowly than ants.

Maybe. Muscular reflexes rely on sending a message from the point of contact to the brain and back to the point of contact, so there is a longer transfer time with a larger body. Speed of messages sent by nerves depends on the study and there's a fair bit of variability there (source: http://hypertextbook.com/facts/2002/DavidParizh.shtml) but if we use a speed of 300 feet per second, two thousand feet tall being who steps on a 15 foot tack wouldn't feel it for 6 seconds and wouldn't be able to move for another 6 seconds - so it's entirely possible that a large being would experience the world around it more slowly, but it's also possible that it could develop faster nerve fibers or more localized response systems.

How we experience time is probably more a factor of evolution than anything else. Quick reaction times and faster observation and recognition can improve the odds of survival, so, I don't think there's any guarantee that a large animal experiences time more slowly, but there might be a general truth to that theory. It has more to do with physiology and evolution than physics.

Another possibility is that our reaction time is related to gravitation and the rate of falling. In very low gravity, where you fall more slowly, reaction time to catch yourself, or adjust your body for the fall might be slower and in high G, reaction times might need to be faster, especially since in high G, beings would probably be shorter. My musings on this, are, of-course, purely theoretical but not really science.

It's a reasonable enough question though a being 1 light year across is hard to conceive, but I don't think there's a clear answer. By watching kittens, that they seem to be able to respond faster and do more in a second than larger animals are, so it seems at least, somewhat true that smaller animals experience a second to be longer than larger animals, but to what extent it's true in a grand sense - I'm not sure.

on the last part, let me quote Carl Sagan:

There are naive questions, tedious questions, ill-phrased questions, questions put after inadequate self-criticism. But every question is a cry to understand the world. There is no such thing as a dumb question

and this, from dear abby (of all places)

There is no such thing as a stupid question if it's sincere. Better to ask and risk appearing stupid than to continue on your ignorant way and make a stupid mistake

https://en.wikipedia.org/wiki/No_such_thing_as_a_stupid_question

I think other answers are insightful but I would like to elaborate them further.

In a nutshell, the question in about an hypothetical brain which has physical dimensions comparable with one light years, and about its perception of time. Since information cannot travel faster than light, the time in which information travel from one side of the brain to the other is comparable to one earthling years.

Well, though hypothetical and highly improbable, this living being does not appear to violate any physical laws, as long as its density is very low. As pointed in one of the answers, such an enormous living being would encounter severe gravitational problems, if its density is similar to that of a planet, or to human flesh. However, there are obviously large objects in the universe, but their densities are clearly much smaller than that...

So, in order to get a better insight about the problem, let us imagine a sentient being, a brain, which is scattered in small units over a whole galaxy. Imagine for example that each star of this galaxy have one of these small units, say neurons, orbiting around, and that these neurons can exchange informations via radio waves, for example. This brain would not violate any known fundamental physical law.

Now, how would these galaxy-scattered brain perceive time? Well, it is difficult to answer a question about something which is not likely to exists...but let us do a gedanken experiment. Imagine that these huge brain listens some music, e.g., Debussy's Clair de Lune, which is about 5 minutes (earthling time). We do perceive the Clair de Lune as a succession of time events with a granular structure (the notes) which build up to form large structures (musical phrases) which are in temporal succession. In some way our brain synchronizes with the music, and we do perceive being at the beginning of the piece, as different as of being at the ending. Does this makes sense for a galaxy-scattered brain? Obviously not. During the 5 minutes when the Clair de Lune plays, the information perceived has had not enough time to travel across even a minimal fraction of this huge brain. This brain can perceive a 5 minutes event similarly to the way we perceive an extremely short subnuclear particle decay. We can observe the decay, but we cannot perceive it as a temporal event.

Tentative answer

I think that at the end of the day, the time needed for information to travel from one side to the other of the giant's brain sets the minimal interval of time between events which can be perceived as temporally separated. This is a minimal bound, since a human brain is the size of fractions of light-nanoseconds, and we clearly cannot perceive time at that scale. In fact, information in the human brain travels way much slower than light.