[Tycho?]

There's something I'm puzzling about regarding black holes:

 

I think it's reasonable to assume that black holes exist. But we know from GPS and other evidence that clocks run slower here on earth than they do up in space. It's not an optical illusion or some kind of observer effect, it's something real, and it's down to gravity. This means time "runs slower" as you near an event horizon, whereupon it stops. Which suggests to me that collapsing stars are collapsing so slowly as far as our time experience is concerned, that they haven't finished collapsing yet. This means there can't be any actual singularities, because as far as we're concerned, the collapse takes an infinite length of time. And if Hawking Radiation is true, the black hole will evaporate before the collapse is complete.

 

Can anybody clear this up for me?

I can add a few comments, other things I dont know too much about. But ignore jackson33, he has no idea what he is talking about.

I dont think time "stops" at the event horizon. Time dilation is related (in some way) to the strength of the gravitational field. The event horizon is just the limit where light can't quite escape. But gravity there is still finite, and so when talking about time dilation effects, I dont think the event horizon is different from anywhere else (except the singularity of course).

As another note, Hawking radiation will not cause most black holes to evaporate. It does mean that black holes radiate energy, but the cosmic microwave background radiation alone is enough to counteract this, so a steller black hole will not have a net loss of mass.

But for the meat of your point though, I dont think I can help you. Ive heard descriptions similar to yours and I'm none too sure what to make of them. Martin might be able to help you here, although I havn't seen him around for a while.

A bit off-topic, but why in the world should NASA be all over this one? NASA gets less than 1% of the federal budget. They are already stretched beyond the limit doing what the President and Congress asks them to do now. Last I checked, developing new power generation techniques is not under NASA's purview.

If this technology were actually cheap, easy and clean then NASA would be all over for its use in spacetravel. NASA is always looking for new tech, and this would be extremely useful to them.

there is no way we fully understand or can manipulate graverty in the same was we understand and can manipulate magnatism or static electrisity, any advances are a good thing :¬)

When you post, please take a moment to read over what you wrote to make sure it makes sense.

Here's the thing. If he was right, and cheap clean fusion was indeed this easy....... where the hell is it? Why has nobody built one? Why is NASA not all over this? Why are scientists around the world not shouting with joy that someone figured it out?

I remain highly skpetical, I doubt this will come through.

then what burns up in space and becomes mass, either falls as acid rain or exits earths atmosphere and is lost mass. the those altitudes I'll pick the latter.

Is english not your native language? You make very strange gramatical mistakes in your posts, it makes me think I am not understanding you.

If a meteor burns up in the atmosphere, the mass is not lost. Most of it will fall to the earth (as dust, not as acid rain). A tiny amount will remain in the atmosphere. Either way, no mass is "lost". It all contributes to the mass of the earth.

I can see why whats-his-face got irritated.

Light is a particle.

Light is a wave.

If you say one of these statements is incorrect, you are wrong, period. In his "pissed off today" post, I saw no errors in physics.

Are you all considering the 21 grams of mass lost by people who die? That is unrecoverable mass. Perhaps you should calculate the number of dead in the world and subtract that from your growth rate.

21 grams lost by people who die? ....what? The mass couldn't possibly be lost. If it were converted into energy it would be like a fusion bomb going off. Even if you got the number wrong, how can any mass just be lost?

i said i suggested it and me-myself-my mind, is not convinced this is not a possibility. my response was to a hypothetical post inferring gravity change was a possible event over time.

 

if your saying all that burns up in space stays there, maybe we should revisit the global warming nonsense with 100 or 200 tons of potentially very damaging materials and discount the non-harmful 98% of atmosphere that is; nitrogen and oxygen.

What in the world are you talking about? I never said anything stays in the atmosphere.

Have you tried wikipedia?

Woah, why sinusodal? I rather doubt the mass of the earth would change periodically.

I think it would be hard to just make up a non-linear function for the growth of the earth in very early days. You'd have to know a fair amount about how planets actually formed to be able to estimate these things. I dont know if anyone has such details on the early formation of the earth.

I was looking for a Science Fiction forum though, a place to discuss science fiction concepts (the science behind sci-fi sorta thing). I stumbled into here, and saw the physics section, and decided to stay.

Check your calculation again, of you would. The earth's mass is 6x10^24 kg, so the increase is less than a part in 10^8, and the acceleration changes linearly with the mass, for constant radius.

 

Actual mass gained is a little less than 100 tons/day (<25,000 tons/year) according to http://www.talkorigins.org/faqs/moon-dust.html

Thanks for seeing the mistake. I thought 1.5% seemed big, but I didn't get around to checking the numbers (or checking the math).

i should research some figures, but the earth is really a heavy place. i do feel you figures are a little high and what reaches the ground is maybe a ton a year. now, quite a few meteors are made up of ice and rock combinations. these burn up quickly and add some to the atmosphere, hydrogen, oxygen and carbon by products from the burn.

It doesn't matter if it burns up or not, its still adding mass to the earth.

And are you saying you think the extinction of the dinosaurs had something to do with a change in earth's gravity?

Quick calculation:

Assume the earth has been adding 200 tons of mass every day, for say 200 000 000 years. This is a mass of 1.46x10^16 kg. This amount wouldn't affect the radius of the earth by a large amount, so we will take that to be constant. This results in 0.15m/s^2 difference back 200 million years ago. Current acceleration due to gravity at sea level is 9.8m/s^2, so thats a change of about 1.5%. Which is pretty large actually. I'm going to go look up some numbers on how much mass the earth gains to see if this number is actually accurate.

Oh! So, Tycho he's like Einstein?

Are you an idiot, or just being a troll?

Social Entropy -- its one of the Penny Arcade subforums. Notoriously rough, although its mellowed out a ton in recent years. Just general conversation and joke making for the most part. Not for serious discussion.

Debate and Discourse --another Penny Arcade subforum, for on-topic conversation.

Ministry of Free Thought -- a subforum of Macaddict, a macintosh computer magazine. Its for discussion politics, religion and other things like that. Only 15 people regularly post there at one time, but I've been a member since I was 14, and I still like it.

Totse forums --- a hive of stupidity for the most part, I spend most of my time there ripping into people who make things up about science.

Has he been this way since birth or did it develop over time? I'm reading a book on string theory and I'm starting to see his name pop up more as I get further along. Is he revered in the science world or is he just another player who happened to get the ball?

Revered really isn't the right word. He's famous, mostly because of his medical condition and the popular books that he has written. As physicists go he is important, but probably not as important as you would think. There are plenty of influential physicists who arn't known in the mainstream at all.

Hawking. Not Hawkings.

Probably not much.

http://www.wikipedia.com

isn't the accretion disk generally a plasma anyways? the collisions betwen atoms(ions if i'm right) would knock electrons off anyway at the temps found in accretion disks before the x-rays did.

Yeah, if something is hot enough to be emiting x-rays its safe to say its a plasma.

swansont: it could make sense to say that SR deserved it but not GR. It all depends on timing. Maybe the Nobel Committe thought that that year GR was good but something else was better. SR and Brownwian recieved no credit as the committe did not want to cause a controversy, with a Jewish man in an anti semetic society. GR, during World War 1, would have been even worse.

Uhhh no. Nobel prizes are given out years after the initial work was done, so time can be taken to properly verify it. His prize for the photoelectric effect came in 1921, 16 years after he wrote the paper. Any prize he got for GR would have been in the 30s or 40s.

I always wondered about this as well, charge seemed like an odd property for a black hole to have.

There are a few disadvantages to a system like that.

1) You have two things to reload. Ammo, and propellant. Two is more akward than a single contained package.

2) Your gun, even with not ammo in it, is now quite explosive.

Quote:How is the earth held at a central point? And how does this provide earth with an intertia?

 

Tycho, imagine a tug-ofwar between two absolutely equal team with each rope tied to a ring that we will use to represent our earth. We are simplifying the problem by using only two team instead of an n-number of teams. Since each team uses identical pulling forces, the ring cannot move. It can be said to have inertia. It is held stationary at one point with a total force that is could be interpreted as a mass.

 

Quote: Mass does not have an apostraphe in it. How is the magnitude of the force the matter/energy relationship of the earth to the rest of the universe? What does matter/energy relationship mean? How does this mean mass?

 

We know that mass does not have an apostrophe in it–I was using the apostrophe as a comical point. Returning to our tug-of-war. If we increase the amount of matter in the earth object, the tug-of-war has an increased amount of pulling teams. This increased n+ number of teams, which is solely due to the increased amount of matter in the earth object, now feels a much greater force. This increase in force represents increased mass which in turn is of a magnitude relationship to the amount of matter in the rest of the universe.

 

What we know as matter is really the sum of the matter in an object plus all it’s internal/external forces which is energy. This, the use of the term matter/enery.

 

Quote: Gravitational force has a fixed limit? What does this mean, what sort of limit?

 

This phrase is part of the statement (If the universe is infinite, then the fixed mass of the earth also tell us that the gravitational force has a fixed limit). This statement is a bit strong. It was meant to imply that the combination an infinite universe and a gravitational that was also unlimited would sort of provide us with an inertia value for the earth that would also be infinite. How many levels of infinities can exist? TreborS

I dont think you know what you are talking about. That first point, about the external forces being equivilant to inertia and mass, or something. Can you back this up numerically? A property of intertia is that an object resists change in motion, but just because something resists a change in motion certainly does not insure that it is intertia. You'll need some equations here to back you up.

I dont follow your analogy with these pulling teams, and increasing the matter/force on the earth, or whatever you are talking about. You'll need to make this explanation far more technical, or go straight to equations.

This omni-directional pulling attraction has the effect of holding the earth at a universal central point which provided the earth with an inertia.

How is the earth held at a central point? And how does this provide earth with an intertia?

The magnitude of this force is in effect the matter/energy relationship of the earth to the rest of the universe and we call it m’ass.

Mass does not have an apostraphe in it. How is the magnitude of the force the matter/energy relationship of the earth to the rest of the universe? What does matter/energy relationship mean? How does this mean mass?

While this is probably true, why does it follow from the previous statement?

If the universe is infinite, then the fixed mass of the earth also tell us that the gravitational force has a fixed limit.

Gravitational force has a fixed limit? What does this mean, what sort of limit?