# What if you fall through space time?

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That which isn't possible unless you are smaller than space time. What would happen?

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What does “fall through” mean?

What does “s﻿ma﻿ller﻿ than space time” mean?

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You can't fall through spacetime regardless of how small the object is spacetime is still present.

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That which isn't possible unless you are smaller than space time. What would happen?

I guess you are thinking of spacetime as some sort of "grid" (perhaps due to drawings that try to represent curvature). It isn't. It is, necessarily, continuous.

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5 hours ago, Strange said:

I guess you are thinking of spacetime as some sort of "grid" (perhaps due to drawings that try to represent curvature). It isn't. It is, necessarily, continuous.

Can you fall through a box? Yes, box are composed of atoms, if you are smaller than an atom you can fall through a box. Space time should technically be composed of some type of structure, like a dough. It is logical to think you can fall through a dough, or space time.

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Space time should technically be composed of some type of structure, like a dough.

Should be? Why? (There is no evidence for this.)

Our model of space-time depends on it being continuous.

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Can you fall through a box? Yes, box are composed of atoms, if you are smaller than an atom you can fall through a box. Space time should technically be composed of some type of structure, like a dough. It is logical to think you can fall through a dough, or space time.

Can you fall through a stage without a trapdoor?

It doesn't matter what the stage is made of.

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Can you fall through a box? Yes, box are composed of atoms, if you are smaller than an atom you can fall through a box. Space time should technically be composed of some type of structure, like a dough. It is logical to think you can fall through a dough, or space time.

No. Space-time should not be comprised of anything like dough.  It is not substance-like at all.   The concept of space-time is just the recognition that the measurements of space and time are frame dependent and not absolute.    The analogy is that in Newtonian physics, space and time are treated like North/South vs. East/West. In such a situation everyone, no matter what direction they are facing, all agree on these directions.  Everyone, for example, agrees that  town A is 40 miles North and 30 miles East of town B.   However the Space-time manner of treating this is that each person uses his own sense of Left/Right and Front/Back.   Thus one person facing one direction will say that town A is 30 miles to the left of and 40 miles in front of town B, while someone facing in another direction would say that town A is 50 miles directly to the right of town B.

It makes no more sense to think of space-time as being "substance-like" than it would to think of Left/Right-Front/Back as being "substance like".    Now I also realize that in GR, it is said that Space-time "curves" in the presence of mass.  And to many people this implies space-time being a "structure or substance".  This is not what this means.  "Curvature" of space-time really just means that the geometry rules governing it are non-Euclidean.  In other words, the rules of plane, Euclidean geometry just don't hold.

Edited by Janus
typo fix

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18 hours ago, Strange said:

Should be? Why? (There is no evidence for this.)

Our model of space-time depends on it being continuous.

Like a chain maybe, radio wave can pass through a box.

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Like a chain maybe, radio wave can pass through a box.

As Janus says, space-time is not a "thing", it is just a set of measurements.

(If radio waves can pass through a box because of the nature of the atoms it is made of; they can't pass through a metal box, for example.)

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22 hours ago, Strange said:

As Janus says, space-time is not a "thing", it is just a set of measurements.

Can the same statement be made about a magnetic field (and any other  field)?

More generally ,can we distinguish between any object and the measurement (=perception?) of it? **

(if we can't ,does Janus'  distinction redundant   except to perhaps say that we can only perceive one object at a time and only extrapolate  subjectively to assume that the "object"  has extent in space and time -and also perhaps to guard against some people's wish to re-etablish an ether?)

**so that we cannot rigorously avoid conflating the external which we perceive  and the internal mechanism with which we seem to interpret.

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On 7/14/2019 at 5:57 PM, Strange said:

As Janus says, space-time is not a "thing", it is just a set of measurements.

(If radio waves can pass through a box because of the nature of the atoms it is made of; they can't pass through a metal box, for example.)

Not if I make myself invisible :D.

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Not if I make myself invisible :D.

!

Moderator Note

...and we're done here.

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