I usually avoid commenting on the looks, clothing, and general appearance of politicians but I must say that I was startled to see photos this morning of Michele Bachmann’s outfit at yesterday’s debate. What with the gold buttons, Nehru jacket collar, and epaulets, she looked like she was auditioning to be the commander of the spaceship in the next film in the Star Trek series.
I am curious if people who are knowledgeable about such matters think it was a good choice for a presidential debate.
This chart from the Tax Policy Center shows that Herman Cain’s much publicized 9-9-9 plan will raise taxes on those earning less than $200,000 per year while lowering taxes for those above, with a huge windfall for the millionaire class. Matt Yglesias puts the numbers into a chart that show how incredibly regressive it is.
Cain’s plan got him attention because of its catchy title. But because it is his only concrete proposal, it is going to hurt badly as the reality of its impact sinks in. He can stave off the inevitable for a while by claiming that all his critics are wrong or have misunderstood it or by weirdly repeating the phrase ‘apples and oranges’, but when even rabid anti-tax nutcases like Rick Santorum says that this plan will raise taxes on 84% of the people, he is in trouble. There is no way that this turkey is going to fly.
I was amused by Cain in yesterday’s debate urging people to ignore all the analysts and do the math themselves. He must be depending on the poor math skills of the general public to save his plan.
Update: jpmeyer in the comments gives an even better graph by Jared Bernstein of the impact of Herman Cain’s plan.
(For previous posts in this series, see here.)
In the previous post in this series, I said that Einstein’s claim that the speed of light must be the same when measured by all observers irrespective of how they were moving led to the conclusion that the rate at which time elapsed must depend on the state of motion of the observer. But if time is not an invariant entity, then we need to be more precise about how we measure it for observers in relative motion to one another so that we can better determine how their measurements are related.
What we now postulate is that associated with each observer is a grid of rulers that spreads out into all space in all directions. At each point in space are also a clock and a recorder. It is assumed that all the rulers and clocks of all the observers are constructed to be identical to each other, the clocks are properly synchronized, and the recorders never make errors. When an event occurs anywhere at any time, the location and time of that event are those noted by that recorder who happens to be exactly at the location of the event and who notes the ruler and clock readings located at the place at the instant when the event occurred. This rules out the need to make corrections for the time that elapses for the light to travel from the location of the event to the recorder.
If there is another observer who is moving with respect to the first, that person too will have her own set of rulers and clocks and recorders spread out through all space, and the location and time of an event will be that noted by her recorder using her rulers and clocks at the location where the event occurs. This set up seems rather extravagant in its requirement of infinite numbers of rulers and clocks and recorders but of course all these rulers and clocks and recorders are merely hypothetical except for the ones we actually need in any given experiment. The key point to bear in mind is that the location and time of an event for any observer is now unambiguously defined to be that given by that observer’s ruler and clock readings at the location of the event, as noted by the observer’s recorder located right there.
What ‘Einstein causality’ says is that if event A causes event B, then event A must have occurred before event B and this must be true for all observers. If one observer said that one event caused another and thus the two events had a particular ordering in time, all observers would agree on that ordering. Thus causality was assumed to be a universal property.
What we mean by ’causes’ is that event B occurs because of some signal sent by A that reaches B. So when the person at B is shot by the person at A, the signal that caused the event is the bullet that traveled from A to B. Hence the clock reading at event A must be earlier than the clock reading at event B, and this muust be true for every observer’s clocks, irrespective of how that observer is moving, as long as (according to Einsteinian relativity) the observer is moving at a speed less than that of light. The magnitude of the time difference between the two events will vary according to the state of motion of the observer, but the sign will never be reversed. In other words, it will never be the case that any observer’s clocks will say that event B occurred at a clock reading that is earlier than the clock reading of event A.
But according to Einstein’s theory of relativity, this holds only if the signal that causally connects event A to B travels at speeds less than that of light. If event B is caused by a signal that is sent from A at a speed V that is greater than that of light c (as was claimed to be the case with the neutrinos in the CERN-Gran Sasso experiment) then it can be shown (though I will not do so here) that an observer traveling at a speed of c2/V or greater (but still less than the speed of light) will find that the clock reading of when the signal reached B would actually be earlier than the clock reading of when the signal left A. This would be a true case of the effect preceding the cause. The idea that different observers would not be able to agree on the temporal ordering of events that some observers see as causally connected would violate Einstein causality and this is what the faster-than-light neutrino reports, if confirmed, would imply.
Note that this violation of Einstein causality occurs even though the observer is moving at speeds less than that of light. All it requires is that the signal that was sent from A to B to be traveling faster than light.
(If the observer herself can travel faster than the speed of light (which is far less likely to occur in reality than having an elementary particle like a neutrino doing so), then one can have other odd results. For example, if the speed of light is 1 m/s and I could travel at 2 m/s, then one can imagine the following scenario. I could (say) dance for five seconds. The light signals from the beginning of my dance would have traveled 5 meters away by the time my dance ended. If at the end of my five-second dance, I traveled at 2 m/s for 5 seconds, then I would reach a point 10 meters away at the same time as the light that was emitted at the beginning of my dance. So if I look back to where I came from, I could see me doing my own dance as the light from it reaches me. So I would be observing my own past in real time. This would be weird, no doubt, but in some sense would not be that much different from watching home movies of something I did before. It would not be, by itself, a violation of Einstein causality since there is no sense in which the time ordering of causal events has been reversed.)
So the violation of Einstein causality, not the theory of relativity itself, is really what is at stake in the claims that neutrinos traveling at speeds faster than light have been observed. This is still undoubtedly a major development, which is why the community is abuzz and somewhat wary of immediately accepting it is true.
Next: What could be other reasons for the CERN-Gran Sasso results?
A ball containing 36 cameras is programmed to take simultaneous photos when it reaches the highest point in its trajectory, providing an instantaneous panoramic view. This not only looks like it would be fun to use, it could have many practical uses, such as seeing over high barriers.
(Via Boing Boing.)
Science has a unique role in the growing recognition that it is the source of authoritative and reliable knowledge. But that carries with it a great burden to make sure that the public’s trust is not abused. Via Machines Like Us, I learned about the General Assembly of the International Council for Science (ICSU) issuing a statement last month on “The Principle of Universality (freedom and responsibility) of Science” that spelled out what the responsibilities of scientists are.
The free and responsible practice of science is fundamental to scientific advancement and human and environmental well-being. Such practice, in all its aspects, requires freedom of movement, association, expression and communication for scientists, as well as equitable access to data, information, and other resources for research. It requires responsibility at all levels to carry out and communicate scientific work with integrity, respect, fairness, trustworthiness, and transparency, recognising its benefits and possible harms.
This followed up on the second World Conference on Research Integrity held in Singapore in July 2010 that issued a statement that “emphasizes the need for honesty in all aspects of research, accountability in the conduct of scientific research, professional courtesy and fairness in working with others, and good stewardship of research on behalf of others.”
Scientists have to be vigilant in maintaining these standards.
There are those who criticize the Occupy Wall Street movement, complaining that they don’t have concrete demands and have not proposed any solutions to the problems. I disagree with that criticism. It seems to me a bit much to expect an unorganized group of people scattered over the globe to come up with solutions to big problems at a time when the US government is so dysfunctional, when it lurches from one crisis to another and is not even able to carry out its minimal function of passing a budget, and when the global economy seems to be so shaky that world leaders seem to be at a loss as to what to do.
[Read more…]
Some time ago I wrote about ultra-Orthodox Jews in Israel raining big gobs of spit on a reporter because she was using a tape recorder on the Sabbath and thus violating one of the numerous rules prohibiting work on that day.
Now we have another disgusting story of Ultra-Orthodox Jews throwing eggs and feces at young girls on their way to and from their school, accusing them of sluttishness. What makes this even more noteworthy is that the targets of this abuse, the girls and their families, are themselves Orthodox Jews but they are considered not conservative enough for these god-fearing people.
I am sure that the people indulging in this appalling behavior are convinced that they are doing the will of god. This is what religious devotion can lead to. Deeply religious people can act like jerks or criminals or thugs or even murderers and actually feel virtuous about doing so, because they think that god commanded them to act in this way.
Richard Dawkins was due to speak at a function hosted by the Center for Inquiry that was to be held at the Wyndgate Country Club in the Detroit area. But some official of the club saw Dawkins interviewed by Bill O’Reilly and decided that he/she did not want to have an atheist soiling their premises so the club canceled the event at the last minute forcing the organizers to find an alternative venue for the sold-out event. The CFI is considering suing the country club for its actions.
Of course, what the country club achieved is to give a huge amount of publicity to an event that otherwise only CFI members and supporters would have known about.
(For previous posts in this series, see here.)
In the previous post in this series, I posed the situation where, seated in my office, I observe two events on the sidewalk outside my window and measure the locations and time of two events and deduce the distance between them and the time interval according to the rules for using my own ruler and watch. Now suppose another person is moving with respect to me (say in a train that passes right by where the two events occur) and sees the same two events as I do and measures the locations and times of the two events and deduces the distance and time interval between them using her ruler and watch. Will her measurements agree with mine?
When it comes to location and distance measurements, it is not hard to see that the two results will be different. When I take ruler readings of the two events, the ruler is not moving compared to the two events. But because the person in the moving train’s ruler will be moving along with her in the train, the ruler readings of where the two events occurred will be affected by her motion. After the person in the train takes the reading on her ruler at the location where event A occurred, by the time the later event B occurs, she and her ruler would have moved along with her train and so the ruler reading for event B would be different from what would have been obtained if the ruler had been stationary. So the locations and the measured distance between the two events based on her two ruler readings will be different from those based on my two ruler readings.
What about the time interval between events A and B? It used to be thought that even though the two observers used different clocks and they were moving relative to each other, as long as the clocks were identical and synchronized properly, the two observers would at least agree on this because it seemed so commonsensical that time was some sort of universal property, independent of the observer measuring them or her state of motion. Time measurements were said to be invariants.
These relationships between the location and time measurements made by observers moving with respect to one another were first postulated by Galileo. It is now known as ‘Galilean relativity’. Galileo used these relations to show why, even though the Earth was moving quite fast through space (a seemingly absurd idea at that time), a ball thrown vertically upwards would fall back down to the same point from where it was thrown, and not be displaced because the Earth had moved during the time that elapsed. This everyday observation had previously been used to argue that the Earth must be stationary but Galileo turned it around to show that it was consistent with the Earth moving.
But one consequence of the assumption that time is an invariant is that if you measure the speed of light (by taking two events, one consisting of light being emitted at one point and the other of it being detected at another point and dividing the difference in ruler readings between the two events by the time interval between the events), you would get different values for two observers in relative motion to each other, since the distances traveled (i.e., the differences in the ruler readings) would be different for the two observers but the time interval would be the same. In other words, the measured speed of light was not an invariant but depended on the speed with which the observer was moving.
What Einstein postulated (based on several reasons that I will not get into here) was that the speed of light was the same for all observers. In other words, it is the measured speed of light that is an invariant, the same for all observers irrespective of how they are moving. One important consequence of this is that the elapsed time between two events is no longer an invariant, and depends on the observer. Time is no longer a universal property but depends on who is measuring it. The difference in measured times is tiny for the normal speeds we encounter in everyday life, which is why we don’t perceive it. But it does leads to things like the celebrated ‘twin paradox’ where if you have a pair of identical twins, one remaining on Earth and the other going in a rocket at high speed to a distant star and returning, the traveling twin would have aged much less than the one who stayed home.
Needless to say, this caused some consternation and it took some time for people to be persuaded that this seemingly bizarre result was correct. What Einstein did was force us to be more precise about how we measure the location and time at which events occur, so that we can meaningfully compare the results of different observers viewing the same events.
Next: Measuring time and space more precisely.
Or so this baby seems to think.