Airbrush

A good example of sling shotting is the Cassini mission to Saturn. It went towards the Sun first and gained speed from the inner planets a couple of times before heading outwards. Then it got another boost from Jupiter. It was a once in a lifetime opportunity, since the planets would not be aligned that way for a long time. "The Cassini space probe performed two gravitational-assist fly-bys of Venus on April 26, 1998, and June 24, 1999. These fly-bys provided the space probe with enough momentum to travel all the way out to the asteroid belt. At that point, the Sun's gravity pulled the space probe back into the inner Solar System, where it made a gravitational-assist fly-by of the Earth. On August 18, 1999, at 03:28 UTC, the Cassini craft made a gravitational-assist flyby of the Earth." http://en.wikipedia.org/wiki/Cassini_mission

Any time we see a star orbiting something invisible, we can calculate the mass of the invisible object and if it is small in size, the only explanation is a very massive, small object. Only a black hole explains this.

Hello Urain. I wish I could comment but it will take too long for me to read and understand your question. Can you condense your question into a few paragraphs? I usually avoid complicated posts.

Yes, at one earth radius (about 4,000 miles) the acceleration is 1G and you are safe. The event horizon is the size of a walnut. To remain in orbit around the walnut you will need to travel as fast as a low-orbit satellite. To orbit the black hole at a distance of only 2,000 miles, for example, you will have to travel at a much higher speed to remain in orbit. The closer you get to the walnut, the more Gs are pulling on you. How fast do you need to be traveling to remain in an orbit of only 10 miles? It seems like some extreme Gs will be experienced when you are only a few miles from the walnut, and that will be enough to kill any human. At some point your technology will be inadequate to keep you in orbit, and you fall into it. How close can you safely get to such a mini black hole if the top speed of your spaceship is 20 miles per second?

Hahaha. Good answer. It all depends on how long we have to react to it. We can get blind-sided any day by a Tunguska sized object that is first discovered only days before impact. If you have only days to react, best thing to do is fire massive kinetic impactors to slam into it and try to deviate it slightly. I hope they have a plan. Recently I saw a TED talk by George Dyson who worked on the original project Orion. They proposed sending a giant spaceship using nuclear explosions as propulsion. It would be so heavy that it would take about 800 nukes to get it out of Earth's orbit. He said he thinks they can use that idea as a means to deliver a rocket to an asteroid in the shortest amount of time. "The original Project Orion was a secret project in the late '50s and early '60s funded by ARPA, the USAF and NASA to design Nuclear Pulse powered spacecraft. They were to be propelled by nuclear explosions. The expanding plasma would impact a cushioned "pusher plate" at the rear of the spacecraft and push it forward." Here is George Dyson:

MigL, I asked this question on a different topic. If we discovered a mini black hole with the mass of the Earth, it would be the size of a walnut. How close could we get to it with our current technology? We could orbit it safely from a distance comparable to the distance of the space station from Earth's center. But how close could we safely orbit this mini black hole? The closer you get to it, the faster your orbital speed needs to be to not fall into it. My guess is that we could not get much closer than 4 thousand miles from it.

On the same topic, but different conditions, suppose we discovered a mini black hole with the mass of the Earth. That would be the size of a walnut. How could we safely approach it? How close could we get to it without getting destroyed? The faster your speed in orbit around it, the closer you could get to it.

"Would crossing the event horizon of a black hole be instantly fatal?" It will be instantly fatal far outside the event horizon. The intense acceleration will kill you, about a Million G's well outside the event horizon. The event horizon only applies to light. Humans are more fragile and travel much slower. Long before you reach the event horizon you will be crushed by extreme G forces from instantaneous acceleration towards the singularity.

How long does it take to be crushed to the size of an atom after penetrating the event horizon for a supermassive black hole? It will not take "quite some time before hitting the singularity. Gettting accelerated to near light speed in a tiny fraction of a second will also cause you to disintegrate.

Even though you may survive crossing the event horizon for a supermassive black hole, you will get accelerated to near light speed in a tiny instant moving towards the singularity, which will make it very hard to see anything. Our brains don't work that fast.

An episode of The Universe stated that upon crossing the event horizon for a supermassive black hole, you would survive until you got close to the center (which seems to me will take less than a microsecond) then you would be killed. Only a stellar black hole spaghettifies. Anyone remember that episode?

I cannot answer any of your questions. All I know is: (1) something allowed the big bang to happen, and (2) that something existed before the big bang. "Big Bang Potential Energy" is just a suggested term to describe the indescribable, and I have no idea what it is. How about calling it "dark potential"? Everything else is empty speculation.

Yes, some prior epoch not connected to our space-time. Our space-time obliterated and superseded, or sprang out of, branched off, whatever pre-existed it.

Then I will try to convince you that there had to be something before the big bang, simply because conditions allowed a big bang to happen. Let's call it "big bang potential energy". I am certain that something like that existed before the big bang. And that is not speculation, that is logic.

Thanks for the interesting discussion above. So what do y'all think there was before the big bang? And answer the question without using the word "nothing" please.

Thanks for the info Arch. Would you say that plutonium is the heaviest element created in a supernova that has a long enough life for us to discover it on Earth?

Can all the other elements found in nature be created by one massive supernova? Or does it take several supernovas to create all the heavier elements? Is it possible that the first stars that formed after the big bang could have been so massive that they created all the elements found in nature when they exploded? Is is possible that there are even heavier elements we are not aware of that could be created by a supernova massive enough? Maybe in some regions of the universe there are found elements heavier than uranium or plutonium.

That is a new definition to me. Can anyone give us a more precise definition of the universe? I don't believe any reputable scientists would agree with your words quoted above. The Big Bang says nothing about the conditions before it. That means anything could have existed before the creation of our universe, even another universe. Why can one universe not be created on top of a previous universe? Maybe another Big Bang will occur in our neighborhood. Or there could be another Big Bang that occurred so far away we haven't seen it yet, not until we are destroyed by it.

If scientists know nothing about what existed before the Big Bang, then it is NOT correct to assume the universe came from nothing. "Nothing" is a very poor term to use, BTW, but it keeps getting repeated above. It is an idiotic term to use in cosmology. The universe as we know it originated with the Big Bang, but the condition(s) that allowed a Big Bang to occur was not "nothing" but rather a profound potential.

You cannot say there was nothing before the big bang, since we know nothing about it. There could have been anything before the big bang.

Welcome aboard. Wow! That all whizzed over my head. Can anyone explain this in 200 words of less using plain English?

Interesting discussion. So I was also thinking that could a nearby supernova "push" hydrogen of the interstellar regions into the area where our solar system formed, and our solar system formed from a mixture of heavy elements from the supernova plus hydrogen that was either blasted off or that was pushed into our area?

"...matter can neither be created nor destroyed...think about that..." "What about matter/anti-matter annihilation?" When matter and anti-matter come in contact they are annihilated, but they release a tremendous amount of energy in doing so. Matter and anti-matter are not destroyed, they are converted into energy.

You can approach the black hole if you are going very, very fast, orbiting a safe distance outside the event horizon, and your clock will slow down. You cannot go inside the event horizon and then return to Earth.

The probability of death by gamma ray burst is very, very small. Smaller than asteroid hits, supervolcanos, and almost any other disaster you can think of. But, over the lifespan of Earth, there is a possibility that one deadly GRB hit the Earth sometime during the past 4.5 Billion years. But for most of that time, nobody would have noticed, except perhaps for some bacteria. "....Now it seems that gamma ray bursts may not pose as much a danger to Earth or any other potential life in the universe, either, since they are unlikely to occur where life would develop...." Thanks for the link Swansont. Interesting article. We are safer than I thought.