re: The mass of a supermassive black hole

quote:

---

How does that work, exactly?

---

How does what work?

Take it to the science fiction board. Black holes aren't real.

What would you weigh at the event horizon?

quote:

---

What would you weigh at the event horizon?

---

Edit: erased earlier post, I found the answer. The formatting on the formulas below are screwed up but can be found in this link. If you were able to stay stationary your weight approaches infinity. Otherwise you're in freefall so you'd be weightless (not massless remember).

LINK

Suppose you are carrying a large and heavy backpack. You can feel the gravitational force of the backpack weighing you down. However this only happens because you're staying a fixed distance from the centre of the Earth i.e. you're standing stationary on the Earth's surface. If you and the backpack were to leap from a cliff then (ignoring air resistance) you would feel no gravity as you plummeted downwards and the backpack wouldn't weigh anything.

If we now switch our attention to the black hole, if you attempt to stay a fixed distance from the black hole (presumably by firing the rocket motors on your spaceship) you'd feel the weight of the backpack, and the weight would get bigger and bigger as you approach the event horizon. In fact the weight is given by:

F=GMmr211-rsr-----v

where m
m
is the mass of the backpack, M
M
is the mass of the black hole, rs
r
s
is the event horizn radius and r
r
is your distance from the centre of the black hole. As you approach the event horizon, i.e. as r?rs
r
?
r
s
, equation (1) tells us that the force goes to infinity. That's why once you reach the event horizon it is impossible to resist falling inwards.

But you only feel this force because you're trying to resist the gravity of the black hole. If you just fling yourself off your spaceship towards the black hole then you will feel no weight at all. You would fall through the event horizon without noticing anything special. In fact you would see an apparent event horizon retreating before you and you would never actually cross anything that looks like a horizon to you.

quote:

---

They don't. Most of this shite is theoretical at best, completely made up at worst. Nobody knows what happens to things sucked into a black hole either. Scientist get together and come up with vague explanations to excite the masses so they will continue to get funding. Most of what happens farther away than Jupiters orbit is a complete guess. They are assuming that the laws of physics on earth apply throughout the galaxy. There is no way to confirm that

---

You're a frickin idiot.

Where were you guys when I asked the OT

quote:

---

1) If you are driving through space at the speed of light and turn on your headlights, does the light proceed forward or stay in the headlight mechanism? 2) What happens to the light from your tail lights? 3) If the cosmic police manage to catch up to you, how would the strobe lights on the officer's car appear to an observer traveling slightly slower than you in the other lane? Edit for those who took physics at community college: Obviously, the vehicles have no mass and are capable of driving in space. Otherwise this would be too easy.

---

Link to the answer, part of it quoted below.


Your question contradicts Einstein's Special Theory of Relativity which states that no object with mass CAN travel at, or above, the speed of light (c). As your car approaches c, its resistance to acceleration (mass) increases so that it would take an impossibly infinite force to actually reach c. Your question, then, is based on an impossible premise. It's like asking 'What would happen if I reached the North Pole and kept going north?'

As you approach the speed of light with your headlights on, however, you would still measure the light beam racing away from your car at 186,000 miles per second (c). A 'stationary' observer watching this happen, though, would not then measure the beam's speed at almost twice c. Relativity says that all observers always get the same measurement for c.

While that may not sound logical or plausible, it happens because what we normally think of as fixed concepts--length and time--are both variable at high speeds. If you observed a car travelling past you at close to c, its length in the direction of travel would appear shortened and the passage of time on board would appear slowed down.


Edit: Another link

The question might then be what would the situation be like if the car were going at 0.9999999 times the speed of light? If you are in the car, and look only at stuff which is traveling along with you at your speed, you would not notice the difference, and the headlights will work normally. If another car is ahead of you traveling at the same speed, then your headlights will light up that other car and you will see it normally. This happens because the laws of physics are the same in all inertial frames of reference (where "intertial" means "moving uniformly without accelerating". Rotating also involves acceleration, so the frame of reference cannot turn).

The road might look strange, however. It will appear to be shortened (Lorentz contracton), and the photons from your headlights will bounce off of the road and back at you with very large energies because of blueshifting. You may not see your taillights reflected on the road either (they will be redshifted), but the car behind you traveling at the same speed will be illuminated by your taillights in the normal way.

If you are not in the car but are standing at the side of the road, then the headlights of the car will make a beam of very high-energy photons (maybe x-rays, maybe gamma rays, depending on how fast the car is going). The light rays from the headlights will actually not spread out but will become more directed along the line of motion of the car because the component of the momentum of the photons along the car's direction will increase due to blueshifting but the transverse components will stay the same.

quote:

---

If you can't see it and touch it, how can you accurately observe and define something?

---

The easy answer to this is you observe it's effects on its surroundings.

quote:

---

I though I saw my dog walking across a field about a mile and a half away. Turns out it was a calf.

---

I guess you think you've made a point?

quote:

---

You think these scientist have any remote idea of what is happening light years away?

---

Much more so than you or I.

The questions I posed are just part of the hoax torture exam I give my interns on the first day of their rotation.