# Biological systems in relativistic effects?

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Not by my sums I wonder where we are differing. I have the time factor between fast ticking very distant observer as t = t_fast *[sqrt (1-r_0/r)] . When r is close to r_0 then you get a rapid change in the time factor with small changes in r

You may be right. That is the same relationship I was using. I was trying to work out what r_0 needs to be, in relation to the length of the arm, in order for the effects to be noticeable (a significant fraction of a second, for example). But I'm not that is the right way to go about it.

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I wasn't looking for a calculation, just a general answer. I don't care what non-zero and non negative length you use. The person could be 100000000000 lightyears large for all I care.

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As mentioned previously in the thread, consider that light travels at around 300,000,000 m/s while nerve impulses from the hand travel closer to 60 m/s. Thus, even without taking time dilation and such into account, the light from a person's hand touching an object always reaches the eyes "long" before the nerve signal from the hand reaches the brain. At normal human scales, the difference isn't great enough to be really noticeable, especially since there are probably differences in how long the brain takes to register sight versus touch.

The effect would, of course, be magnified in the case of a person 100 billion light-years tall. Assume each arm would then be something like 50 billion light-years long, and we get the light from the tip of the hand taking about 50 billion light-years to reach the eye, with the nerve impulse taking closer to 250 quadrillion years to reach the brain.

Edited by John
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I wasn't looking for a calculation, just a general answer. I don't care what non-zero and non negative length you use. The person could be 100000000000 lightyears large for all I care.

A thousand light year larger person would see their arm touching things long before they felt them even without time dilation coming into play because light travels much, much faster than nerve impulses. Over very small distances (like the length of your arm) the difference in arrival time is negligible to the point of being undetectable to your brain. Over very long differences, the amount of time that your nerve impulses would lag behind the light accumulates and would become very noticeable in short order.

Time dilation could, in principle, create a similar effect to distance in this case. If you have a signal moving at light speed racing a signal racing at nerve speed out of an extreme gravity well, time dilation could increase the amount of lag between when you receive the light speed signal versus the nerve speed signal as compared with the same distance traveled without the gravity well.

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It's still wildly beside the point, still copout answers because the focus obviously isn't the natural inertial delay they already have, its any extra delay they might have due to time dilation.

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I wasn't looking for a calculation, just a general answer.

The general answer is: it depends.

You have rejected every answer given. I don't know what you want. Nor why.

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It's still wildly beside the point, still copout answers because the focus obviously isn't the natural inertial delay they already have, its any extra delay they might have due to time dilation.

And the "natural" delay can be extended by time dilation in the same way that it can be extended by distance.

I'm really not sure what more you're looking for.

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The delay is extended, that's it, that's all I was looking for. Obviously, I was in no way looking for answers involving someone's arm getting ripped off (which I specified at the start) and obviously saying there's a natural delay has no intrinsic connection to time dilation whatsoever. All of these issues could have been solved simply by slowing down and taking the time to accurately read what I said.

The answer is not "it depends," this is not a series of multiple scenarios, this is one very very specific scenario. You originally stated you had no answer after posting material which did not follow the parameters I set, then you said the answer was the violations of the parameters I set, and now you're saying it depends. If you don't know the answer, then please don't unnecessarily convolute my threads.

Edited by MWresearch
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The general answer depends because you haven't said:

- The mass of the black hole

- The distance from the black hole

- Whether the black hole is spinning or has charge

- Whether the person is falling or orbiting (or using magic to hover)

So: yes there will be a delay. It might be large enough to notice. Or it might not. The situation might be physically impossible (in which case all answers are meaningless). Choose whichever answer that makes you happy, if you are not prepared to ask a specific question.

Don't ask, "what would happen in this poorly defined and probably impossible situation" and then get upset when you get a variety of unhelpful and contradictory answers. The problem isn't with those trying to help you.

Perhaps you could explain why you think the question is interesting and then we might be able to address that.

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Except you obviously didn't read the first post because then you'd see how nothing you said actually matters for this thread

There is some amount of time dilation regardless of the black hole's mass

There is some amount of time dilation regardless of the black hole's charge

There is some amount of time dilation regardless of the black hole's spin

There is some amount of time dilation regardless of whether or an object is falling or orbiting

You stated you had no answer and then flip flopped after convoluting the thread and purposely ignoring the parameters I set, making your posts strictly off topic and against forum rules.

Mordred indirectly brought up a good point that was actually helpful in simplifying the problem which is the question of whether or not the hand and the brain are in the same frame. Since the signal needs to travel distance over time to get to the brain from the hand, there's a pretty fair chance that they aren't, which would mean that there would be an extended delay in the amount of time it takes for someone to perceive the touching of an object through feeling.

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Except you obviously didn't read the first post because then you'd see how nothing you said actually matters for this thread

There is some amount of time dilation regardless of the black hole's mass

There is some amount of time dilation regardless of the black hole's charge

There is some amount of time dilation regardless of the black hole's spin

There is some amount of time dilation regardless of whether or an object is falling or orbiting

Agreed (see my first response). But the amount of dilation is unknown if none of those factors are known. So one possible answer is that the effect of time dilation would be too small to notice. Another possible answer is that there would be a noticeable delay so touch and sight would be out of sync (like watching a movie with the audio and video out of sync). My calculations suggest the latter is impossible because of the tidal forces, but imatfaal says otherwise so I assume I was wrong about that.

purposely ignoring the parameters I set

But you didn't set any parameters! That is why I suggested it would only be possible to answer if you did.

Since the signal needs to travel distance over time to get to the brain from the hand, there's a pretty fair chance that they aren't, which would mean that there would be an extended delay in the amount of time it takes for someone to perceive the touching of an object through feeling.

Agreed. But whether that is significant or noticeable is unknown. (Without more information).

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I don't care about the exact amount of time dilation, as I said I only wanted a general answer. Does it get delayed due to time dilation, yes or no? That's it, that's all you need to think about and yet you managed to ruin that simple question and turn it into an entire convoluted section of nothing but babble. I specifically specified that I was neglecting harmful effects of tidal forces and harmful effects of force due gravity against what they would be hovering on (which would answer your orbital question anyway) that would harm the person, those are the parameters, a person or a structure resembling person with the ability to withstand up to gravitational force near the surface of a black hole to allow an electrical signal to pass through it from end to end with the focus solely on the general amount of time it would take for the signal to be perceived through the sense of feeling after observing it optically. Would there generally be an increase in the amount of time it would take to feel something? Yes or no? That's it.

Edited by MWresearch
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But Strange answered that question in post 16 (see his first three words), and you just said that was "a copout answer".

Of course, maybe you just meant that the "in practice" part was a copout, though I don't see why you'd say that; but in any case, you didn't indicate that his answer was what you were looking for, though now it seems to have been just that. That's probably why other members assumed you were looking for something different, which seems to have led to some confusion.

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Saying there's a delay because the arm gets torn off isn't the same as a delay due to time dilation which makes it not what I'm looking for. Even though mathematically you could technically have infinite time dilation at the relative boundary of the black hole which would in practice be the same as never having an arm since in either scenario you wouldn't be able to feel anything, I am specifically talking about above the event horizon, not at or inside it.

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I think you may be misreading his post. The relevant thread of conversation is as follows:

But that's what I mean, would time dilation actually create a delay in the nerve signals?

followed by

In principle, yes.

In practice your arm would be torn off before you noticed.

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To me it sounds like he is making a snide remark by saying there's a delay because someone's arm gets ripped off.

In either case, the lack of an answer doesn't excuse purposely adding clearly irrelevant convolutions. Obviously the charge of a black hole isn't remotely related to this problem.

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I don't care about the exact amount of time dilation, as I said I only wanted a general answer. Does it get delayed due to time dilation, yes or no?

Yes.

Happy now.

Yes, thank you.

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