## And the real reason for expansion is ....

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Ann
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### Re: And the real reason for expansion is ....

60moo wrote:
Something relevant to this topic that has always eluded me: When an object is accelerated towards the speed of light, how much of the applied energy goes into the increase in velocity of that object, and how much goes into increasing the object's mass?

All of it, and all of it. They're not competing. You will get an increase of mass according to KE = (m-m0)c^2. You will also get an increase in velocity according to KE = m0c^2 (c/sqrt(c^2-v^2) -1)
I found this extremely interesting, but I need a bit more clarification. I don't speak mathematese, sorry,although I do realize that mathematics is a language all of its own that can't really be translated into other languages. Even so, Chris, I'd like you to try.

This is how I understand the acceleration and increasing mass thing. In order to make a physical object accelerate, you need to impart a parcel of energy to it (you need to give it a "push"). In the world inhabited by us humans, dealing with speeds that are possible for us humans, almost all of the imparted energy with be transformed into increased speed for the object. In other words, step on the accelerator and you will go faster without putting on weight. (Or increasing your mass, sorry, because putting on weight and increasing your mass is not necessarily the same thing.)

But as your speed increases more and more, less and less of each additional "parcel of energy" will actually increase your speed. More and more of each added unit of energy will increase your mass instead.

The way I understand it, this relationship between mass and speed has something to do with the fact that it is impossible for a physical object to move faster than light, or even to move as fast as light. When you begin to approach the speed of light, most of each additional unit of energy will make you more massive than you were before, and less and less of each additional unit of energy will increase your speed. In the end more energy will just make you more massive without increasing your speed at all.

That is how I understand it. I totally believe you when you say that the mathematical formulae that you quoted makes this relationship between speed, mass and energy crystal clear. But I, who don't speak mathematese, find myself swimming in muddy waters.

Is it possible for you to explain these things in a more non-mathematical way?

Ann
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astrolabe
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### Re: And the real reason for expansion is ....

Hello Ann,

Interesting inquiry. Since mass is a function of density vs. volume one would maybe benefit by setting a criteria for the nature of the object. In other words, is this object accelerating under it's own power or not. If it is then the argument is valid but still opens the door to my usual nitpicking approach:

Nit #1) Since the composition of the object is unknown let's assume it is iron.

Nit #2) The ability for this object to maintain it's pre-accelerated size/density requires certain amount of internal energy/pressure or else it would collapse into itself.

Nit #3) If the object is a Black Hole then all bets are off!

Now if this object is accelerating under it's own steam then the Law of Conservation of Energy would require that energy contained within the body that is used for acceleration will reduce the amount left over to maintain size via internal pressure, such as electron movement, heat, and other normal atomic structural functions. That being said, energy loss given over to acceleration will result in an increase in mass/density until, at least IMHO,at the speed of c (or close to it) nearly all, if not all, of the internal energy will be given over to acceleration and the result will be that the object will have become a Black Hole with virtually no energy left to maintain any volume whatsoever.
Last edited by astrolabe on Thu Jun 03, 2010 11:49 am, edited 1 time in total.
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makc
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### Re: And the real reason for expansion is ....

Ann wrote:This is how I understand the acceleration and increasing mass thing. In order to make a physical object accelerate, you need to impart a parcel of energy to it (you need to give it a "push"). In the world inhabited by us humans, dealing with speeds that are possible for us humans, almost all of the imparted energy with be transformed into increased speed for the object. In other words, step on the accelerator and you will go faster without putting on weight. (Or increasing your mass, sorry, because putting on weight and increasing your mass is not necessarily the same thing.)

But as your speed increases more and more, less and less of each additional "parcel of energy" will actually increase your speed. More and more of each added unit of energy will increase your mass instead.
as Chris already said (I think), energy is not "spent" to increase your mass. no matter what speed you run at, same "parcel of energy" adds same "parcel of mass". the thing about high speed is that you need more "parcels" to get extra mph than you would need at low speed.

dougettinger
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### Re: And the real reason for expansion is ....

If we knew how to use our frontal lobe we could communicate anywhere in the universe without our cell phones. And it is far easier to communicate inwardly than outwardly. Our bodies are simply universes turned inside out. I am sorry that I cannot illustrate that concept. But I agree with you; an illustration would prabably be misleading.

DBE
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Ann
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### Re: And the real reason for expansion is ....

Astrolabe wrote:
Since mass is a function of density vs. volume
This doesn't sound right to me. I thought that mass is mass, regardless of the volume containing this mass. When I was a kid, we used to asked each other this question: Which is heaviest, a pound of iron or a pound of cotton? The answer is that they weigh the same. To put it differently: Imagine that you somehow managed to sqeeze the Earth so small that it collapsed into a black hole, since the concentration of the Earth's mass into such a small volume (say, the head of a pin) would punch a hole right through the fabric of spacetime. Or maybe the only thing that would happen is that the escape velocity at the surface of the head of this Earth-mass pin would be larger than the speed of light. So in theory you could turn the Earth into a black hole. But that in itself wouldn't increase the mass of the Earth, would it?

Makc wrote:
no matter what speed you run at, same "parcel of energy" adds same "parcel of mass".
That makes sense to me. However, does that also mean that you always increase your mass when you increase your speed? So if you are driving your car and increase your speed from 30 mph to 50 mph, does that mean that your mass increases along with your speed, however small the increase of your mass may be?

Makc also wrote:
the thing about high speed is that you need more "parcels" to get extra mph than you would need at low speed.
Yes, that makes a lot of sense. It may indeed be harder to increase your speed from 200 mph to 210 mph than it is to increase your speed from 20 mph to 30 mph.

So you need a lot of extra energy to increase your speed further when you are moving at speeds close to the speed of light. In fact, you probably need a lot of extra energy to even maintain such a very high speed for any length of time. In order to increase your speed at all when you are already moving extremely fast you have to add a huge helping of energy just to maintain your speed, and on top of that you have to add even more energy to actually increase it. But as you keep adding that much energy, you will increase your mass all the time.

It seems clearer to me now. Thank you.

Ann
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rstevenson
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### Re: And the real reason for expansion is ....

It might be difficult to imagine a self-propelled vehicle trying to reach the speed of light, because there's the added complication of using fuel and therefore changing the mass of the vehicle for mundane reasons while you're trying to calculate its increase in mass due to Relativity.

Instead, think of an outside agency propelling the thing -- the best example we have at hand is a particle accelerator such as the Large Hadron Collider. The particles in such an accelerator are pushed up to near the speed of light by magnetic fields, and when they've reached their top speed they can have masses which are thousands of times greater than their rest mass. But it took a huge amount of electrical energy to run the magnets to push them to that speed.

Rob

Chris Peterson
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### Re: And the real reason for expansion is ....

Ann wrote:So you need a lot of extra energy to increase your speed further when you are moving at speeds close to the speed of light. In fact, you probably need a lot of extra energy to even maintain such a very high speed for any length of time. In order to increase your speed at all when you are already moving extremely fast you have to add a huge helping of energy just to maintain your speed, and on top of that you have to add even more energy to actually increase it.
Your first assessment is the right way to look at the issue- the faster you are moving, the more energy it takes to get going a little faster (an effect that becomes more extreme as you approach c). But it doesn't require any energy to maintain your speed. Even at relativistic speeds, Newton's First Law still holds.
Chris

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Beta
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### Re: And the real reason for expansion is ....

Ann wrote:
When an object is accelerated towards the speed of light, how much of the applied energy goes into the increase in velocity of that object, and how much goes into increasing the object's mass?
All of it, and all of it. They're not competing. You will get an increase of mass according to KE = (m-m0)c^2. You will also get an increase in velocity according to KE = m0c^2 (c/sqrt(c^2-v^2) -1)
Is it possible for you to explain these things in a more non-mathematical way?

Q: When I track dirt into the house, how much of that dirt goes into making the floor dirty, and how much into making the house heavier?
A: Well, all of it makes the floor dirty, and all of it makes the house heavy, it doesn't divide up.
Q: But as I understand it, if I track dirt into a clean house, it'll make the floors dirty without making the house heavier. But when the house is really dirty, I mean dirt piled up almost to the ceiling everywhere, then when I track in dirt most of it goes to making the house heavier and very little of it goes to making the floor dirtier, and that's why a house can't get dirtier than dirt-to-the-ceiling.
A: No, when you track dirt into a clean house it makes the house heavier, just not very much, you tend to notice the dirty floor more. And when you bring more dirt into a dirty house it does make the floor dirtier, but it takes a lot of extra dirt to make a noticeable difference. Either way, the new dirt makes the floor dirtier and makes the house heavier.

Beta
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### Re: And the real reason for expansion is ....

astrolabe wrote:The ability for [an] object to maintain it's pre-accelerated size/density requires certain amount of internal energy/pressure or else it would collapse into itself.
Where on Earth are you getting your information?

When, say, a candle burns, it just gets smaller and smaller until it's gone (in the ideal case). Internal pressure and "collapsing in on itself" have nothing to do with it. A caseless solid-fuel rocket with no payload works the same way.

Ann
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### Re: And the real reason for expansion is ....

Astrolabe, I've been thinking a bit more about what you said. It could be that you are absolutely right about what you said about volume and density, or at least that you and I mean the same thing!

And Chris, thank you for your answer. Yes, you are right of course: Assuming there is no friction in space, an object would need no extra energy to maintain its speed.

Thanks again to everyone who answered!

Ann
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Beta
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### Re: And the real reason for expansion is ....

Ann wrote:So if you are driving your car and increase your speed from 30 mph to 50 mph, does that mean that your mass increases along with your speed, however small the increase of your mass may be?
Yes, if you drive a mid-size sedan the mass increases by a couple of nanograms, comparable to the mass of a grain of pollen.

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### Re: And the real reason for expansion is ....

Ann wrote:
Yet the whole universe is connected in a form of space time grid.

What does that mean? Most of the Universe is not connected to the rest.
Ah, Chris. The danger of illustrations.

I've just tried to convince you that the Sun ins't yellow. Stubbornly, you have refused to acknowledge that I'm right.

Yet the most important reason why people think that the Sun is yellow is that we keep saying that it is yellow, and that we keep "painting" it yellow in our illustrations and photographs.

A space shuttle is seen transiting the Sun. What color is the Sun? It's yellow. Not because it is yellow, but because it was made to look yellow. In this image, too.

Why would people believe that there is a huge space grid connecting everything in space with everything else? Because our illustrations make it look as if there was such a grid.

That's why illustrations are so dangerous! Because we don't know what we see, we see what we think we know. Our thought processes and ideas are shaped by the illustrations we have seen. Hence the supposed yellow color of the Sun and the supposed all-encompassing space grid that keeps everything in the universe cosily connected. Well, it would make the universe a great place to make cell phone calls - you'd never be in a place where you wouldn't be able to call anyone else anywhere in the universe, would you?

Ann
If A photon can effect Gravity, Then a Photon is directly connected to Time. The space/time Grid is very real. If a mass at rest and a Zero mass at light speed are connected, It would of course direct us to the vast distances of the universe.

You may find this interesting
Click to play embedded YouTube video.
Mark
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makc
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### Re: And the real reason for expansion is ....

LOL @Beta, dirt analogy is both correct and amusing

astrolabe
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### Re: And the real reason for expansion is ....

Hello Beta
Beta wrote:When, say, a candle burns, it just gets smaller and smaller until it's gone (in the ideal case). Internal pressure and "collapsing in on itself" have nothing to do with it. A caseless solid-fuel rocket with no payload works the same way.
True, but your candle will never accelerate and, as a result never gain mass. Also, without the energy of it's matter structured at the atomic level it will collapse- wick burning or not.. Suppose one adds energy in the form of heat to air, or iron, what happens? Of course expansion will take place Remove that energy and those two elements will collapse back to normal. Now start removing even more energy in the form of heat or whatever to use as an accelerant and the atomic structure will become more and more compacted as movement (even at the atomic level) slows all the way to say, nearly zero. Now use up the energy of the leftover matter itself, which in order to attain the speed of light will require all of it, and still the object gains mass. And so on until it's mass is so great it goes beyond the neutron stage and becomes a Black Hole at c. Coldest, darkest, deadest, at-rest place in the Universe- the result of trying to go 186,000 miles in one second.

A caseless solid fuel rocket with no payload is actually a perfect case in point. Again, it's about gaining mass through acceleration. So as it approaches the Speed of Light any so far unburned fuel will become more compacted as it's mass increases and, IMHO, the result will be the same as above.
"Everything matters.....So may the facts be with you"-astrolabe

dougettinger
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### Re: And the real reason for expansion is ....

rstevenson wrote:It might be difficult to imagine a self-propelled vehicle trying to reach the speed of light, because there's the added complication of using fuel and therefore changing the mass of the vehicle for mundane reasons while you're trying to calculate its increase in mass due to Relativity.

Instead, think of an outside agency propelling the thing -- the best example we have at hand is a particle accelerator such as the Large Hadron Collider. The particles in such an accelerator are pushed up to near the speed of light by magnetic fields, and when they've reached their top speed they can have masses which are thousands of times greater than their rest mass. But it took a huge amount of electrical energy to run the magnets to push them to that speed.
RStevenson makes an excellent point. So what is the expectation for the percentage of the speed of light that the Large Hadron Collider can achieve ?

So in order to find the proposed very massive Higgs Boson, the LHC will both increase the speed AND the mass of small particles before colliding them ?

Doug Ettinger
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rstevenson
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### Re: And the real reason for expansion is ....

I believe the current generation of colliders can push particles to essentially the speed of light -- if they need to for a particular experiment. And the mass will increase as the particle is accelerated.

Rob

makc
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### Re: And the real reason for expansion is ....

@astrolabe you should _not_ be able to form a black hole by simply accelerating some amount of matter. from the math it follows that time slows down for moving spaceship - thus, if it would form a black hole as seen from outside at t = 10 (from common time sync event), in its own time this should happen at t < 10. on the other hand, on spaceship board you don't see any mass gain, so it basically never turns into black hole, at least not until t ~ +∞, which is >> 10. so, our idea that moving object turns into black hole leads to contradiction and, therefore, must be false. also keep in mind that well-known solutions by kerr and that swartzschield (or whatever it is spelled) guys are for black holes that exist forever, so you can't really use them to back your argument up.

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### Re: And the real reason for expansion is ....

astrolabe wrote: ...your candle will never accelerate and, as a result never gain mass.
No, my candle will burn, and therefore never gain mass.
astrolabe wrote: Also, without the energy of it's matter structured at the atomic level it will collapse- wick burning or not.
With zero energy content, it will not exist. "Collapse" has nothing to do with it.
astrolabe wrote: A caseless solid fuel rocket with no payload is actually a perfect case in point. Again, it's about gaining mass through acceleration. So as it approaches the Speed of Light any so far unburned fuel will become more compacted as it's mass increases...
The mass of the rocket will decrease. The mass of fuel (which is all the rocket is) will decrease. Honestly, this is why we like to use non-self-propelled objects in our thought experiments. By introducing self-propulsion when it is not necessary to the point you've simply confused the issue.

makc
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### Re: And the real reason for expansion is ....

makc wrote:...so you can't really use them to back your argument up.
and even if you really can, I think length contraction in the direction of movement will compensate for mass gain (i.e., you have more mass, but also have to compress it much more to reach event horizon)

astrolabe
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### Re: And the real reason for expansion is ....

Hello Beta and makc,

Thank you both for your comments. At 185,999.9 MPH it would be a real bear to gain that .1 MPH, eh? Beta, the self propulsion idea was not mine initially but my comment about the solid fuel gaining mass only refered to the assumption that there would be solid fuel left over in order for any increase in mass to be possible. And yes, self propulsion in these thought exercises DO absolutely confuse issues and so I'm glad I'm not the one anyone in the real world calls for the calculations!
"Everything matters.....So may the facts be with you"-astrolabe

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### Re: And the real reason for expansion is ....

An interesting read. I wonder what else shape shifts, or disappears and reappears else where?

Physicists spot shape-shifting neutrinos
"PARIS: Scientists in Italy are 98% certain that they observed 'neutrino oscillation', a phenomenon that proves the mysterious sub-atomic particles have mass and will modify the Standard Model of Physics.

The finding could have major implications for our understanding of matter in the universe, the researchers said,
Mark
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bystander
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### Re: And the real reason for expansion is ....

Neutrino oscillation: OPERA sees first tau-neutrino

This probably has nothing at all to do with expansion. While it might have some implications for Dark Matter, expansion is driven by Dark Energy.

BMAONE23
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### Hawking program

I saw an interesting program on the Science Channel where Stephen Hawking was talking about gravity and time travel. In the program e stated that If you were to travel in close proximity to a large gravity source (orbiting a black hole) that Time would be sufficiently slowed down for you to age significantly slower than others elsewhere. The Subject was broached by discussing what happens to Clocks in space vs. clocks on the ground. Basically, the farther away from Earth (the gravity source) you get, the faster the clocks and therefore time runs. This started me wondering (a danger I know), that If the farther you get from your localized source of gravity (Earth, Sun, MW Galaxy, Galactic Local Group), the lessening of the influence of gravity on time there is, then this would give rise to the appearance of things moving faster as they moved farther away from your frame of reference WRT your local gravity source.
Could this Time Dilation effect be the cause of the perceived expansion?

Chris Peterson
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### Re: Hawking program

BMAONE23 wrote:This started me wondering (a danger I know), that If the farther you get from your localized source of gravity (Earth, Sun, MW Galaxy, Galactic Local Group), the lessening of the influence of gravity on time there is, then this would give rise to the appearance of things moving faster as they moved farther away from your frame of reference WRT your local gravity source.
Could this Time Dilation effect be the cause of the perceived expansion?
No. The effect of gravitational fields on time is very non-linear. The effect is only significant when the fields become very large- as when you are near a black hole's event horizon. For all practical purposes, there is no effect for ordinary fields such as we experience here, or some point in deep space experiences. All that matters is the difference in gravitational potential between two points- and that difference is small between here and the edge of the observable universe.
Chris

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### Re: Hawking program

And somebody else saw the same program as me and came up with the same conclusion. You want to link this bystander? or shell I do it tomorrow?

tc