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[SniHjen]

0 mass * 100000000000% increase in mass?

don't give me relativity crap.


light isn't affected by gravity, in fact, nothing is.

Gravity bends space-time, and like marbles rolling over a slated surface, light (or an object with mass) will change direction.

[Starver]

Generate a tiny, tiny PRETTY FREAKING tiny black hole, something of such a little volume its attraction would only make up the gravity of earth, i guess.. but we will never have such technology.

Much apart from the problem of tides[1], how are you going to keep the black hole where you want it?  Bolt it to a bulkhead?

And if it's the mass of the Earth (which it won't be, you'd go for something smaller, which you sit nearer, as in the footnote, but it's still going to be hyper-massive) you're now trying to propulse a ship with a total mass certainly no less than that of Earth.  Away from whatever point it is that you had just managed to bring at least one Earth-mass of material into in order to form the black hole and ship itself.

Best bet: find a way to shove black holes around, grab a handy one and build a Dyson Sphere-style ship around it, expending most of your energy moving the black hole around but keeping some spare to make sure the relatively featherlight Dyson Ship around it maintains positional parity with it, lest it go all eccentric and Bad Stuff happens.  But by the time you can shove BHs around, in the first place, the rest should be fairly simple.



[1] Lay on the floor.  Now get up and lay on your table.  The inverse square law means that you're getting a small (but essentially negligible) difference in the amount of gravity you're feeling at each distance from the earth's barycentre.

Try the same with any blackhole-like mass designed to sit a hundred metres away and give you 1G at your current position.  Moving a metre "up" would (if my mental arithmetic is holding up) give you an 0.98G gravity.  50 Metres down (not so difficult to do proportions) you'd be experiencing 4G, being 25m away from the source means 16G, 12.5m away is 32G.  (Ignoring all kinds of stranger effects, that I'll miss out of these in-the-head calculations.)  And the 'sweet-spot' for this black-hole is quite narrow.  To fit sizeable amounts of accommodation and workspace without undue discomfort at the lower levels or heading into inconventiently low gravity at the upper levels demands a larger black hole, set at a greater distance, such that the zone if 1G+/-10% (say) is enough to contain everything one would want.  (Perhaps as a spherical 'world' around the point source of gravity.)[/1]

[Durin Stronginthearm]

But then something moving at light speed DOESN'T increase in mass at all, so the whole argument is pointless.

Yes, it does - it's one of the implications of Einstein's famous E=mc² equation.

[GlyphGryph]

Yes, it does - it's one of the implications of Einstein's famous E=mc2 equation.

I don't usually do this, but... this is idiotic. Your statement. Mostly because it ignores the portion of my post THAT DIRECTLY ADRESSES IT. Einsteins equation ONLY applies to relativistic mass! The comment you are responding to EXPLICITLY stated it was operating under the assumption of classical mass.

I'll repeat this again - if your using relativistic mass, light has mass. But it's not common to use relative mass. It is a fundamentally different concept than classical mass, but it is the one Einstein used in some of his papers and where people arrive at faster objects having more mass. If this is the type of mass we're discussing, photons have mass.

So for the rest of this conversation, why don't we distinguish? Say rest mass or rel mass to indicate which you're talking about, and maybe we can say something meaningful.

[Durin Stronginthearm]

Yes, it does - it's one of the implications of Einstein's famous E=mc2 equation.

I don't usually do this, but... this is idiotic. Your statement. Mostly because it ignores the portion of my post THAT DIRECTLY ADRESSES IT. Einsteins equation ONLY applies to relativistic mass! The comment you are responding to EXPLICITLY stated it was operating under the assumption of classical mass.

relativistic mass

Please explain what you think this means, as I don't think you have the slightest clue.

[GlyphGryph]

Here, have the first google link:
http://math.ucr.edu/home/baez/physics/Relativity/SR/mass.html

I just skimmed it, so I have no idea how accurate it is, but it seems to provide the basic info you'll need.

[Durin Stronginthearm]

Here, have the first google link:
http://math.ucr.edu/home/baez/physics/Relativity/SR/mass.html

I just skimmed it, so I have no idea how accurate it is, but it seems to provide the basic info you'll need.

No, explain it in your own words. Anyone can quote a page, it doesn't mean they understand it.

[lemon10]

It doesn't matter if he understands it. What matter is if he is right.

[GlyphGryph]

Are you going to make some sort of point?
Relativistic mass is mass as a value proportional to an objects total energy. In this framework, light has mass, since it has energy.

So here's the question for you:

No, anything moving at lightspeed has infinite mass

From where do you derive this statement? I'm not saying your wrong, I'm just wondering if you understand what that actually means.

[Il Palazzo]

O.k., I'll bite, because throwing snarky comments at arrogant youth has only so much appeal.

Classical mass is a special case of the more general term, known as relativistic mass.
It's special, because it's only applicable to those problems, where the system is not moving at a speed high enough for the relativistic factor to cause noticeable difference in results.
That's why you can only use classical mass(treating it as equal to rest mass of an object), if you are not going to consider speeds approaching c(for V<0.3c the difference is small enough to be neglected, unless you want a very precise answer to the problem at hand).
And that's why, whenever you're going to think of something going real fast, you can't use the classical mass.

Now, relativistic mass is just the rest mass multiplied by the relativistic factor(γ = (1–v^2/c^2)^–1/2), so when you have a particle with no rest mass(a photon), it being multiplied by that factor still nets 0.

Also, any object with non-zero rest mass gets more massive as it approaches c, asymptotically approaching infinity at V=c.

Once again: you can't freely choose to use classical or relativistic mass on a whim. You can only make your life(i.e.calculations) easier by disregarding the γ factor, if your velocities are also classical, and even then you should keep in mind that you're sacrificing some precision there.

[GlyphGryph]

Welp, I was wrong. I forgot that E=mc2 isn't the general equation (which has more factors) and several other important bits, and I was operating under a definition of relativistic mass that is fairly obselete, and different from the common definition of the same phenomena. I lose.

[Virex]

O.k., I'll bite, because throwing snarky comments at arrogant youth has only so much appeal.

Classical mass is a special case of the more general term, known as relativistic mass.
It's special, because it's only applicable to those problems, where the system is not moving at a speed high enough for the relativistic factor to cause noticeable difference in results.

Wait, I thought the speed of the system as a whole was not of importance, but only the relative speeds of the components?

[Sean Mirrsen]

Why the differentiation, exactly? Just because we're faced with an odd-behaving particle-waveform thing, we have to invent special clauses for laws? A Star Trek science officer would figure it out in less than ten minutes.

Seriously though, the whole thing with relativity reminds me of a particularly devious crossword puzzle. You can get seriously stuck by incorrectly answering a question early on, especially if you chance upon lucky matching letters in the other answers you derive from it. If our assumptions about the nature of light are wrong, but still right enough to allow us to "fit words into the puzzle", we could become stuck unless we care to look deeper into the basis of things. Light could just be a 3D representation of a 4D waveform, possessing the odd properties we see it display, like changing "velocity" in time (changing frequency) instead of changing velocity in space, etc.

[Il Palazzo]

O.k., I'll bite, because throwing snarky comments at arrogant youth has only so much appeal.

Classical mass is a special case of the more general term, known as relativistic mass.
It's special, because it's only applicable to those problems, where the system is not moving at a speed high enough for the relativistic factor to cause noticeable difference in results.

Wait, I thought the speed of the system as a whole was not of importance, but only the relative speeds of the components?

I appologize, bad wording. Indeed I meant the components within the system.

[Lagslayer]

The theory of relativity treats time as a dimension or force that can be munipulated and traveled through, and this has problems with it. I redirect you to my argument on another thread.

http://www.bay12forums.com/smf/index.php?topic=79862.0