Airbrush

Once you accelerate, but whatever means, to any speed in outer space, you will continue at that speed indefinitely, until you crash into something. The rarified atoms in outer space will very slightly slow you down with a tiny amount of friction, but the stopping distance will be very, very long. So how do you dodge a bullet on your way to another star traveling at 10%C?

"...The telescope doesn't seem to expend any energy, or do any "work", in the Physics sense of the word. The telescope (in its simplest form) is just two pieces of unmoving glass: the object glass and the eyepiece. Which just passively transmit light." The lenses of a telescope bend light rays and focus them. You look through the eye piece, expending energy doing so. The telescope does a little work and you also work to see Saturn. Both you and the telescope do a little work, applying a little force through a little distance.

"...Moore's law state a doubling of computer power every 18 to 24 months and as 100 years equals 50 doublings as 24 months or 1,125,899,906,842,624 times the computing power now..." Does anyone take this optimistic estimate seriously? If computer power is doubling every 2 years (or less as you state) that does not mean it will remain at that rate indefinitely. Not even for several decades. Anyone else as optimistic about doubling computer power?

"Galaxies are "anchored by a ...what-turns-the-super-galaxies-on/Super-Massive Black Hole..." (SMBH). The word "anchored" makes it sound like SMBH are what holds a galaxy together. Their mass is relatively tiny in relation to the total mass of the central region of a galaxy. What "anchors" a galaxy is dark matter.

Spyman: "AFAIK the Kerr solution have a limit of maximum angular momentum for rotating Black Holes which sets a maximum spin speed for a certain mass, but different mass affects both the Event Horizon radius and the angular momentum. The Black Hole GRS1915+105 with roughly 14 solar mass have a theoretical rotation limit of 1 150 spins a second but I don't think that is an absolute maximum spin rate regarding all Black Holes independent of their mass." Yes, I just found that also by Googling: "This black hole is about 14 solar masses. At the point of the event horizon, the black hole is spinning at over 950 times per second…. or 50 percent the speed of light. "According to theory, the absolute maximum rate at which this black hole could possibly spin, essentially the speed of light, is 1,150 times per second." http://www.nasa.gov/vision/universe/starsgalaxies/spinning_blackhole.html

Exactly. It doesn't make sense. Can someone please explain it? Did someone make a mistake entering that in Wikipedia? Thanks for commenting but I think you are not correct. Black holes have event horizons which should be visible as a dark circle over a stary field. The volume inside the event horizon is empty space, but the boundaries of this should be very tangible. Also the singularity at the center of a black hole takes up no space. A black hole is all empty space except for the singularity, if there is no accretion disk remaining. The mass of any body is not annihilated. It's mass adds to the mass of the black hole (not much because most of it flies off in energetic sparks that don't go into the black hole). This additional mass will increase the size of the event horizon sphere slightly.

Doesn't a black hole need to be rotating at relativistic speed in order for the singularity to be flattened? The highest rotation possible is under 1,000 revolutions per second. Why a ring shape and not a flattened disc shape? How can a black hole have a ring shaped singularity? This defies reason it seems to me because the center of a ring is empty space. How can the very center of a black hole be empty space? A black hole that is not feeding would appear like a flat black sphere. If the Earth could be crushed down into a black hole it would appear like a flat black marble only an INCH in diameter!

You're only concerned about iron? There are all kinds of particles, from tiny to giant boulders flying around out there at tens of miles per second. The good news is most of that stuff is inside our solar system. The bad news is we have no idea what you might run into while cruising at high speed towards another star system. How quickly can your starship dodge a bullet?

Nice You Tube, thanks for that. It is about "dark flow" so I don't know what "brown dwarfs negate..." has to do with that? Is dark flow something outside our Big Bang? That model seems like another Big Bang is bumping up against the edge of our Big Bang. From Wiki: "Dark flow is a term from astrophysics describing a peculiar velocity of galaxy clusters. The actual measured velocity is the sum of the velocity predicted by Hubble's Law plus a small and unexplained (or dark) velocity flowing in a common direction. According to standard cosmological models, the motion of galaxy clusters with respect to the cosmic microwave background should be randomly distributed in all directions. However, analyzing the three-year WMAP data using the kinematic Sunyaev-Zel'dovich effect, the authors of the study found evidence of a "surprisingly coherent" 600–1000 km/s flow of clusters toward a 20-degree patch of sky between the constellations of Centaurus and Vela. The authors (Alexander Kashlinsky, etc) suggest that the motion may be a remnant of the influence of no-longer-visible regions of the universe prior to inflation. Telescopes cannot see events earlier than about 380,000 years after the big bang, when the universe became transparent (the Cosmic Microwave Background); this corresponds to the particle horizon at a distance of about 46 billion (4.6×1010) light years. Since the matter causing the net motion in this proposal is outside this range, it would in a certain sense be outside our visible universe; however, it would still be in our past light cone...." That seems interesting. How else can something "outside our visible universe" still be in our past light cone? The Great Attractor however, is more localized, between 150 and 250 Million light years away. And even the Great Attractor is getting pulled in the direction of dark flow. Suggestion to moderators, perhaps rename this post with a descriptive title, like "Dark Flow"?

So all we can say about the speed of an electron is that it moves less than the speed of light? How about an approximation? About half light speed? Or very much slower? It doesn't have a very great distance to travel to be high revs per second.

Thanks for the info. I was thinking of the speed of the electron in orbit around a nucleus. How many revolutions per second? What is the average circumpherence of an electron's orbit? Then I can calculate the speed in orbit.

Anyone know what the average speed of an electron? For example, the speed of electrons in the atoms of some common solids, liquids, and gases at room temperature?

One day on Mercury is equal to 176 Earth days.

What speed does an electron move around a nucleus?

It takes a disaster, like what we see in Japan, to get the industry to fix safeguards so even with a great earthquake and tsunami, a nuclear reactor should be isolated and insulated enough to not cause any problems. New reactors will be built from these lessons learned. Nuclear power is here to stay, we should learn to live with it safely.

I think the answer to all your questions is yes. Ceres is the largest asteroid in the asteroid belt. It is now called a dwarf planet. It is less than 600 miles in diameter and contains 32% of the mass of the entire asteroid belt. There are not many large objects in the asteroid belt. http://en.wikipedia.org/wiki/Ceres_(dwarf_planet)

Are nuclear reactors isolated on rollers to allow the earth to move under the reactor during an earthquake? If not, why not? Major skyscrapers are built on rollers or springs, or whatever means to isolate the building from harmful shaking.

Maybe the proportions of a balloon are not realistic. You envision, as I did, an empty central region, or perhaps a super-supermassive black hole created the way a supernova creates black holes, with an expanding shell with a thickness greater than our visual horizon (which is how far? about 50 Billion light years?). The central void would be Trillions of light years across. And our Big Bang is just one of many, a speck on an enormous shell which is much older than 13.7 Billion years? I'm afraid we are on the verg of getting sent to the speculations department.

owl: "...the "age" of the cosmos we can see is fairly well estimated, based on... well... what we can see... This should address your objection, airbrush...." I'm sorry but this does not answer my objection. Remember, I was in agreement with you about the "thick-skinned-balloon-analogy" until I realized this created a model that was far too big to have expanded that size in only 13.7 Billion years. If the thick skin is thicker than our visual horizon then the diameter of the balloon is Trillions or Quadrillions of light years across (if not millions of time larger than that). How could the balloon grow so big in only 13.7 Billion years?

I like that title "Space". My mind chatter wants to add "...the final frontier. These are the voyages of..." "...Is there a distinction between the "universe" and "space"? I see the two terms used interchangeably quite a lot." The universe includes space and matter. Space is only a medium between atoms of matter, with virtual particles popping in and out.

The problem now is your "large enough scale" is too large for a Big Bang that originated only 13.7 Billion or so years ago. That kind of large scale is too large for the amount of time the universe existed. I hadn't noticed this until now, sorry. And cosmic inflation was supposed to have lasted only at the beginning before the universe was much larger than a basket ball.

Your worst case scenario will defeat a watertight car, but in less severe conditions an ordinary car that is watertight with a few simple ventilation features, could provide the difference between life and death. The car would be designed bottom heavy to automatically right itself if tumbling over and over, and it will float indefinitely. Air ventilation will be re-established automatically after snorkel is clear. Of course occupants in car should wear seat belts to survive tumbling. I agree that a waterproof bunker is a better solution. Maybe a community shelter on the highest ground available and quickly accessible to the neighborhood. It could have multiple redundant snorkel air intakes and one or more exits designed to facilite exit thru mounds of debris (sliding door).

What expands is the space between matter. There has to be matter in space. To say only space expands is meaningless. If there is no matter there is no space-time and no expansion.

Larger countries have more area for quakes to happen. Countries with a lot of coastline will have more tsunamis.

Spyman: "It is not only the best theory we have, it is totally without competition, there is currently no other model that can explain our observations. "Do you like Owl also reject Relativity and have your own personal diverging variant of that theory too?" I don't reject relativity of any sort. Thanks for posting the observational evidence above. And yet after reading it I don't see how it rules out what I will call the "Revised Balloon Analogy (RBA)". How does the observational evidence show that our region of space is not comparable to a tiny area inside the giant expanding skin of the balloon, and the skin of the balloon is over 50 Billion light years thick?