Telescope Reviews: Do you accept anything as impossible?

Wow, a lot of interesting points here in this thread.

Do you accept anything as impossible?

Yes! It is not possible that I won the lottery last year. I did not enter. Even if they gave me the money they would be doing so in error because I did not legally enter. I am comfortable with the notion that this is impossible.

If the word impossible is to have meaning then something must actually be impossible. The word is however constrained by a set of assumptions that are usually unstated.

When asked is something possible as a physicist, my answer is constrained by my understanding of physics. For example I find it amusing to tell people that I know how to build a time machine. Later I tell them that it only works in the forward direction and I have no theoretical basis for a machine to go in the reverse direction.

If I am asked if it is possible to do something as an engineer. I use a different set of criteria. No longer am I allowed to use unobtainable materials or scandalous amounts of energy. From an engineering prospective I can build a Starship Enterprise that would have many of the key features of the version D used in the TV show called TNG. However, I can find no practical way to fuel the thing. To go from stationary to c/2 would require about 80 times the mass of the ship in H2. To do a one way trip to anywhere would require 80 squared and a round trip requires 80 to the 4th power times the mass of the ship in fuel. These are not achievable by any technology I can imagine and we have not yet turned on the warp drive.

I compare this to the fate of the old NASA jet packs. Yes they work and 4 were built. We do not use them because of the fueling problem. They could only fly for about 35 seconds. The weight of the fuel must be lifted with the payload prior to use. Adding more fuel added to the weight and did not add to the flying time. A point of diminishing returns was reached and development ceased. Like my time machine the jet pack was possible but not useful.

I do not agree with the assessment of the TV show that it is impossible to get to nearby stars as I have been aware of an architecture for this for many years. I assert that solar sailing will allow a large ship to travel to a handful of nearby stars within a human life span ( 30 -40 years round trip.) One can imagine that we will do this within the next 200 years. It is certainly not impossible in principle. Neither physics nor engineering prohibits such travel.

For many years I have heard the lamentation of those who hang their hopes on some theoretical break through that will sweep away the speed of light limit. To those I suggest more reading. While the natural speed limit does make long distance travel seem to be precluded one must read the rest of the theory. The time dilation works in favor of the traveler. If one can travel near the speed of light this dilation effect slows the passage of time for the traveler relative to a stationary point such as the origin and the target. This means that our range is very much larger than we at first imagine at the expense of loss of relationships with those who do not travel.

If a 20 year old traveler takes a trip at near light speed that last for 1 year, it is possible that the travelers parents will have died of old age upon his or her return at the age of 21. In fact the world may change in some substantial way which my be displeasing to the returning traveler. This is the risk taken by the relativistic traveler. But the traveler is not prohibited by relativity from visiting the center of the galaxy. Such things are possible and the effects have been observed in the laboratory.

To the original question we do have to admit that nature seems to have handed us some fundamental limitations. We must face these. A large part of my interest in physics is about drawing lines between what nature allows us to do and what it does not. It is always possible that our understanding will change but I do not find this productive. New theories are generally developed by those who are dedicated to understanding what is there. Einstein did not just say what if measurements of c were always the same. He was responding to the observed fact that all measurements of c came out the same. He asked what else must be true if that is true. This lead him to relativity. The attitude is what is nature. Many are motivated simply by the fact that they do not like the answers we have so far. I fall among those who want to imagine everything that can be done with the understanding we now have. This is why I have little interest in new theories. I am not waiting for anything. I just would like to understand what we do have and push that to the limits.

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Michael

ATM: 6" F/9 Newtonian Travel Scope
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