A Barrier to Understanding

Most people have heard of Chuck Yeager.

This guy was the test pilot for the Bell X1-A and he was the first person to "break the sound barrier".

What that actually means is that his craft went faster than the speed of sound in air.

A lot of people who do not understand much physics ask the same question about light.

"Is there not a light barrier to break also?" they cry.

The answer is no, for the reasons specified below.

Sound travels in air, and is a vibration of air molecules.

Light travels in a vacuum.

There is no reason why an aircraft can surpass the speed of sound in air, as the effect largely is governed by the doppler effect, which is the same effect that police sirens seem to sound differently when they pass you.

But Einstein produced equations that clearly showed that anything travelling at the speed of light (except photons, which are massless) will end up with infinite mass. try pushing an infinite mass beyond the speed of light and I think it will be found that it is quite difficult.

The thing about space speed is that because mass increases the faster you go, it gets ever harder to push it. The technical way to say this is that the energy from the push goes to increase the mass, not the speed.

The more you push, the more of your push goes into the mass increase.

Oh, and another thing, if your craft gets very near the speed of light, time stops for it.

The Death Star is real ! ! !

Which image seems more familiar? The one on the left or the one on the right?

Well, we all know the Death Star, as invented by George Lucas in Star Wars in 1977, the left image, but what is the right-hand image all about?

The right-hand image is, in fact, a real photograph of one of Saturn's moons, and her name is Mimas. This moon was unknown in 1977 when Star Wars came out, and was not discovered until 1981 when the Voyager spacecraft (launched in 1977!) visited the Saturnian system.

When scientists first saw the huge crater, now named Herschel, they were quite literally astonished out of their shoes. Had George Lucas some prior knowledge? Was he, in fact, an alien himself?

This image of Mimas was taken with the Cassini craft's cameras and is the best we have. The angle by which the camera has caught Mimas is no accident.

Notice how, in the photo of Mimas, there is no "star-background", like the Death Star has. This is because the light from the "star-background" is so faint, AND out of focus, you cannot see it in the image.

Sometimes science kicks up something which almost defies description in terms of surprise and wonderment. This is just one of them, and one of the reasons why I love my physics.

"I have a really bad feeling about this"

It has been reported that the Space Shuttle Discovery is missing some tiles from the heat shield.

This is the worst possible news the astronauts up there can receive. Bearing in mind that I have intermittent Internet access, and I only learned this from CNN on tv, I may be mistaken into thinking they are in grave danger.

But in the last post but one I expressed my fear that they may be in real trouble.

Seems I was right.

I wonder what NASA will do now? Effect repairs? Order them to stay at the Space Station until further notice?

These last series of postings after "Hold That Thought" were written over a period of about 10 days, but will all have similar posting dates, as I have had to write and then save to FD.

I Have a Bad Feeling About This....

February 1st, 2003....Columbia Space Shuttle destroyed upon re-entry (Yes, Q, we know you said that!) due to debris from an SRB removing a heat-shield tile from the wing.

July 27th, 2005... Discovery Space Shuttle filmed having the same problem of debris falling off the SRB.

July 28th, 2005... All Space Shuttle flights grounded indefinitely, whilst the crew of Discovery are still in orbit attached to the International Space Station.

NASA say that is all ok as all aspects of the Shuttle in question have been "digitally photographed" and have been found to be "acceptable".

They have been given the go-ahead to try re-entry (Q-squared).

NASA have played it down, but I think these guys (Captained by a GIRL!) are in real trouble.

Just my opinion.

Got your Space-Sickness pills?

Eposode IV : A Distant Hope .

(please note that all the scientific stuff in this post is factual, surrounded by my verbosity)

Space travel huh? Yeah, well, ok, we have allegedly done it between here and the moon. Takes three days and nights to go each way.

Pretty slow by most standards, but it is the fastest we can attain at present.

The science writers would like to believe that one day we will travel along with light at more or less the same speed. (nothing can accelerate to beyond the speed of light, but you can come as close to it as physics will allow).

If we were to do this, they say, interstellar space travel would be a reality.

Most scientists agree that this may well come about. Just a matter of engineering. It would still take the craft 4.2 years to get to the nearest star, but hey, that's physics!

But there is a more burning problem, not even realised by most people. Interstellar space is not empty. In fact it is populated by at least one proton per liter. Buzzing through this "density" at near light speed would mean that even a single proton would go straight through a normal hull, not to mention any passengers.

And travelling so fast would mean you would get a lot of them since you travel so far in a short space of time.

Simply put, if the ship did not fall apart from hull breaches, the passengers would be dead from radiation poisoning long before they had gone a light month!

Given that attaining super velocities is an incredible hurdle to overcome, the problems don't end there. Some way has to be found to deflect these "protons" from our desired trajectory before they fry us. It has been suggested that an enormous dipole magnetic field facing forward would be of help.

Theoretically, yes, as Brent Spiner would say.

But there is still a problem. The dust. Cosmic specks of matter that are uncharged and hence cannot be deflected by a magnet. it is known to exist in vast quantities from the pictures taken of distant galaxies. Even one of these, at such extreme velocities, would destroy the ship.

It has been conjectured that an ion gun, forward facing, could put a charge on these specks, and our dipole magnet could deflect them.

Problem solved? No way. The ship is travelling at near light-speed, and the effects of having a forward-pointing ion cannon, whose ions travel at near the same speed, will have to involve relatavistic dynamics, and the equations for these calculations are formidable to say the least. And then there are the equations for the deflecting magnetic field, which also travels forward at the speed of light....

My point is, that the road to "Stardom" is not just beset by the "speed" problem.

This is why I love my physics. I get to understand, for free, a lot more than I actually set out to do.