big = slow

[bo198214]

Has anyone an explanation, why big things seem to be very slow?
There are countless examples:

* Big animals live averagely longer than small animals.
* Earth around sun needs 1 year, electron around proton some nanoseconds (?).
* Avalanche seemed to happen in slow motion when seen from a distance (though not for the people running away from it).
* Big ships seems slower than boat.
* Elephants and giraffes seem to run in slow motion.
* Fixed stars seem to be fixed.
* humming bird and sparrow has faster flap than eagle
* etc etc

I know that big ships can be faster than boats, and that earth orbits around sun, faster than every transport on earth.
But in some way the frequency of things slow down.

Any explanations of this?

[moonlord]

Well, all I can say is Earth rotating around Sun in nanoseconds would have required a lot of energy to accelerate the planet... I've asked myself the same question, though...

[jinydu]

In my opinion, your comparison of the Earth moving around the Sun and the electron moving around the proton with big ships and small ships doesn't really make sense. The first comparison is a measure of frequency (Hz) while the second is a measure of speed (ms^-1).

But perhaps Kepler's Third Law can explain some of your questions. Kepler's Third Law (roughly, this is admittedly a simplified version of the real thing) states that for solar system with only one star whose mass is much larger than those of the planets (assumed to have approximately circular orbits), the period, T of a planet's orbit is related to its orbital radius, r, by:

T^2 is proportional to r^3

Thus, as r increases, so does T.

[bo198214]

In my opinion, your comparison of the Earth moving around the Sun and the electron moving around the proton with big ships and small ships doesn't really make sense.

Its up to you what do you want to explain.

[jinydu]

Well, the "fixed stars" and "avalanche" examples are easy enough to explain: parallax. A fixed displacement of an object looks smaller and smaller the farther you are away from that object. This is because the actual displacement of the object subtends a smaller angular displacement across your eye. It is the same reason why, if you are standing on a train looking out the window, nearby trees appear to zoom by while distant mountains appear to move much more slowly.

But perhaps the question you really wanted to ask is that:

Do there exist general scaling laws so that when you increase the physical size of all parts of a system by a constant factor, while keeping some quantity (such as density) fixed, the frequency of some process in the system increases?

I think you could go some way towards answering this question by choosing a simple system whose properties can be solved for analytically, and working out the details.

[bo198214]

Well, the "fixed stars" and "avalanche" examples are easy enough to explain: parallax

Hmm, is not completely satisfactory. If someone drops a stone, then the stone does not seem to fall slower only because i am standing more away from him, does it? But the phenomenon, that one seem to drive slower on a broad street also points to parallax.

But perhaps the question you really wanted to ask is that:
Do there exist general scaling laws ...

No, that would be your kind of question. I only made some observations and now gathering explanations. Maybe we can identify some laws, connections or explanations.

[Hugh]

Hi bo198214,

Elephants and giraffes seem to run in slow motion. humming bird and sparrow has faster flap than eagle

Well, larger body parts have more mass and inertia to keep them from changing direction quickly. Also, larger objects are normally viewed from a greater distance, so their movements seem slower than something small and close up. Parallax is a big factor.

Something I've always wondered about that is related to this topic is the idea of a fractal or liminocentric universe. I've thought that if our universe is fractal, then what is happening on the relatively smaller scale is occurring at a much faster rate than what is happening on the relatively larger one. Here is a link to the idea of a liminocentric universe and the higher dimension connection for those interested: A Conversation with Physicist Brian Greene

[Nick]

Don't bigger objects produce more friction?

[jinydu]

Not really; the sun orbits the center of the Milky Way with almost no friction at all.

[houserichichi]

The sun spins around the milky way at incredible speeds at that! There does exist this little detail called inertia though...

[Nick]

But there's still some friction.. space is not a total vacuum. And don't the planets need to overcome the force of gravity of other planets as well? Doesn't that slow them down too?

Then again, if a planet is bigger, it is less effected by the gravity of other planets.. but still, its something to consider.

right? :?

[houserichichi]

On minute scales the force of gravity from a star in a galaxy billions of light years away affects Earth's rotation around the sun. It just so happens that most of those outside forces are negligible.

I'm curious what you mean by "less effected" in your second paragraph. As gravity is nothing more than the warping of spacetime all things, big and small, will undergo the same "force" when they pass through warpings caused by the small planet. What makes things appear strange, though, is that the larger planet's mass warps space as well so when it approaches the smaller one the smaller little planet "sinks" into the warp rather than the big into the little's. Did that make sense?

Anyway, think simple wave mechanics and you'll know what I mean (interference and combining waves)

[Nick]

What makes things appear strange, though, is that the larger planet's mass warps space as well so when it approaches the smaller one the smaller little planet "sinks" into the warp rather than the big into the little's. Did that make sense?

That was actually what I was trying to say in my second paragraph! :wink:

btw, i've always wondered, houserichichi, how do you prounounce houserichichi?

[DenijsD]

As usually on this forum, there is a lack of common sense in this discussion. :twisted:

Big things to seem slow, but when you measure the actual speed of things, there not really slow.
That is because you have to be at some distance to see big things move (Parallax)(Boat, star, avalanche)(Why don't ask the people in Thailand that got washed away by the Boxing day tsunami how fast it was), or you have no references (Earth, imagine the Earth being on the M25, spinning 'round London at the same speed as it does spin around the sun) or long legs travel more distance (elephant/giraffes (Horses in ancient time had short legs and flat feet, but in order to make them faster the grew and stood upon their tows, now they are fast even in a gentle trot) or big wings move more air (Eagle).
Big dogs usually life shorter than small dogs as well. Parrot can get very old, Turtles as well, even they smaller ones

There are many logical explanations for these things. Why don't you guys (and girls) use some common sense!!!
Big things that are slow though are them big lorries on the Motorway to work, causing all those traffic jams around Amsterdam in the morning….

[moonlord]

The alive things cannot be discussed objectively. The way they move is part of the evolution. As for the planet/electron comparison, take into account the energy required to get a planet moving from 0 to 22 km/s and the energy an electron needs to reach 99%*c.

[pat]

F = m a

??

[Nick]

Hey, I just realized.. this is the Relativity forum, right?
Maybe we could use relativity to answer this; something like:
"The speed of an object is determined by the distance of your frame of reference"

Or something like that.

[jinydu]

"The speed of an object is determined by the distance of your frame of reference"

That doesn't make any sense. The speed of an object does depend on your frame of reference, and if you an object's velocity in one frame of reference, you can calculate its velocity in another frame of reference, provided that you know the relative velocities of the two frames.

You don't even have to know Einstein's relativity to understand that; it is apparent from Galilean relativity.

[Nick]

Yeah, I know it sounded stupid.. that's why I added "or something like that" at the end, hoping someone else could make sense of it.. :wink:.

Guess not!

[houserichichi]

btw, i've always wondered, houserichichi, how do you prounounce houserichichi?

House (like the word) rih-key-key. Way to let the cat out of the bag!

[Nick]

House (like the word) rih-key-key. Way to let the cat out of the bag!

Woops! I didn't know it was supposed to be a secret! :0

[papernuke]

another object that is larger than one smaller than is would obviously be slower. it would be because even though an object with more mass has a greater gravitational pull, a small object like an electron and a proton would only have a very small amount of gravity but it dosent need a lot to pull itself around

[moonlord]

Your post doesn't make sense.

[Keiji]

I think he means a heavier object has more inertia, thus, it is more difficult to accelerate it. That doesn't necessarily make the object slow, however.

[Nick]

I think he means a heavier object has more inertia, thus, it is more difficult to accelerate it. That doesn't necessarily make the object slow, however.

...just requires more force to accelerate and de-accelerate

[batmanmg]

if the earth attempted to speed up the trip around the sun... wouldn't it just pull further away?

[moonlord]

How (on Earth ) would the Earth try to "speed up the trip around the sun" !? We ain't got nitrous oxyde installed yet .

[bo198214]

if the earth attempted to speed up the trip around the sun... wouldn't it just pull further away?

The orbit velocity becomes faster the *nearer* the object is to the sun.

[Hugh]

if the earth attempted to speed up the trip around the sun... wouldn't it just pull further away?

The orbit velocity becomes faster the *nearer* the object is to the sun.

But if the Earth got hit by a HUGE meteor in the same direction that it was going around the Sun, it would speed up, and would move further away from the Sun wouldn't it?

[bo198214]

Am not quite sure, I suppose it goes into a wider orbit.
But its average velocity is slower there.
(If it goes into an orbit at all, but not just flies away.)