What is a scientific analysis, and why should we understand and do it?
- Science is a process, not a collection of facts
- Science can be driven by curiosity or the need to know about observed
phenomena: often, curiousity leads to practical knowledge!
- Scientific analysis relies on observations, i.e. measurements, or data
- Observational measures always have some level of uncertainty associated with them:
without knowledge of this uncertainty, it is difficult, if not impossible, to interpret them.
All measurements should include an estimate of their uncertainties!
- A basic level of uncertainty comes from the apparatus used to make the measurement.
- Additional uncertainty may come from intrinsic statistical variation of the
thing being measured.
- Additional uncertainty may come from variations within a population, if
an average quantity is being measured
- observational data may be incomplete, or biased
- Sometimes errors are small compared to what you're trying to measure, sometimes
they are large. You need to know!
- Improvement in the ability to measure things (i.e. with smaller errors), or clever,
creative new ways to measure things often leads to advances in understanding.
Astronomy example:
- Example: shape of the Earth
- Sometimes new data makes old questions obvious
- Still, shape of Earth was known more than two thousand years ago! This was
because of some clever, creative, ideas: shadows (sticks and eclipses)
- Note that this question, which was probably very curiousity-driven originally, had
great practical consequences
- While you may not feel you have the expertise to comment on issues that you haven't studied,
you can still judge whether claims have considered errors in measurement
- Just because there are errors in measurement doesn't mean you can't ever determine anything: if
differences are measured that are larger than errors, they are believable!
- observations often lead to scientific models, or interpretations/hypotheses
- Sometimes multiple models may be consistent with observed data
- New, or better (lower errors!), data can sometimes resolve problems
- Example: Earth/Sun motion and parallax
- Scientific theories or laws are proposed to explain scientific models
- Theories address the question: "Why?" and often explain multiple
models with a single unifying theory. Example: the Earth moves around the Sun
because of a force called gravity, which also explains motions of
objects on Earth!
- Use of the word "theory" is the scientific sense may be a bit different
from how it is commonly used: in science, a theory means a very carefully
tested (see next point!) concept, not a wild idea!
- the term ``law'' seems to usually be reserved for theories that
have a quantitative mathematical formulation
- The validity of scientific models and theories
- It is very difficult to prove that a model or theory is absolutely true
- It is often easier to prove that a model or theory is false!
- To be a good theory, many people have to attempt to prove it
false, but fail to do so
- A good theory will also make predictions for observations
beyond those which motivated the theory, predictions that can
be verified or falsified
- A good theory is often simple; given two acceptable theories,
the simpler one, or one that explains more phenomena, is generally
preferred
- Models that are backed up by a theory are preferred those that are not
- Science in the real world!
- Although the scientific process is well defined, in practice things
are sometimes harder than it seems to figure out!
- Because of measurement errors, it is not always trivial to decide whether
new measurements are inconsistent with existing models or theories
- People are often reluctant to give up long-held beliefs!
- Even many things we take for granted as common knowledge now
were not always believed, and the transition from older, incorrect
ideas to newer ones was not instantaneous!
- often applied to complex systems, e.g. weather, human body, etc.,
where we don't know enough to understand how things work from most basic
physical laws
- The scientific process has a lot of applications in
improving our understanding and our lives: e.g., medical, sanitation,
weather, technology, etc.
- some science issues require decisions or action before complete knowledge is
obtained. Example: climate change
- Science and journalism. Given lots of people, there are often
multiple opinions. Are they all equally valid? What is "balanced" coverage?
- Science and politics. Many people have strongly held opinions
based on political principles or associations
Judge the data for yourself? Science by consensus of experts?
- In many cases, people make decisions based on information provided
by others; the answer to the question "how do we know" is
that someone else told us. While in some cases it is possible to
try to determine the data upon which these opinions were based and
draw your own conclusions, in some cases you just need to try to
assess what sources are most reliable
- Hallmarks of good science
- Reasonable assessment of errors
- Skepticism and qualification of opinions
- Ironically, this qualification is often interpreted
as indicating invalidity of conclusions!
- Although skepticism is good, skepticism must eventually be backed up by
measurement and their associated errors
- Lack of vested interest in the results
- Peer review, reproducibility of results
- Willingness to reconsider
- States not only what is known, but what is not known
- Problem: bad science?
- problem of fradulent science: rare
- problem of self-proclaimed scientists: the information age, institutional names,
and peer review.
- problem of vested interests: not rare
- Pseudoscience: ideas to explain phenomena which may sound scientific, but have
been rejected by studies using scientific methodology
- Examples: "paranormal" phenomena, psychics, astrology
- Increasingly popular, perhaps driven by the increasing
complexity of the modern world
- Existence of pseudoscience makes it harder to benefit from
science, because some people have a hard time distinguishing them
- Some pseudoscience is very profitable for its proponents
- Hallmarks of pseudoscience
- Unwillingness to relinquish theory even after observations
fail to support it, often by continuing to add revisions
- Not peer reviewed
- often claims to understand things completely, rarely discusses
what it doesn't explain
- Astronomy and astrology
- At least an awareness of astrology is very widespread
- Astrology is something which purports that the position of the planets
and the stars at the time of your birth determines the course of your
future life.
- Is astrology a science? There is nothing about this hypothesis
which is directly non-scientific; scientists are free to come up with
whatever crazy ideas they want. However, the process of science is
asking questions about hypotheses, so any good scientist will ask the
questions: does the hypothesis of astrology work, i.e. is it supported
by observations? Is there any known physical mechanism/theory by which
we expect astrology to work?
- There is no evidence that astrology actually works. Note that the
predictions of astrology may work sometimes; almost certainly,
some of these predictions will work sometimes by chance! Certainly,
astrology is not a fully deterministic theory; if it claimed to be
so, even a single example of a failed astrological prediction would
invalidate the theory. But even as a statistical theory, astrology
fails to be validated by experiment. Here is a
link to some studies
on the predictions of astrology.
- There is no physical mechanism for astrology to work. It turns out
that all of the phenomena that we see in the universe around us can be
explained with only four basic forces: gravity, electromagnetism, and
two nuclear forces known as the strong and weak forces. Via these forces,
the location of planets and stars at the moment of birth are not relevant,
and besides the whole idea is a bit strange since we know that humans
develop over a nine month period before they are born.
- Certainly, the widespread practice of astrology, namely horoscopes, is
incredibly suspect. One only needs to look at the
different horoscopes for a given day
predicted by a variety of astrologers!
- Here
is a nice article and discussion about astrology.
- Astrology is an examle of what is known as a pseudo-science,
or a superstition. There is a real and fundamental difference between
a science and a pseudo-science. This lies in the degree of scrutiny to
which hypotheses are subjected. In sciences, people try hard to
disprove theories.
- Some information on various astronomical pseudoscience
- Is it ok to regard pseudo-sciences are harmless
entertainment? Maybe, depends how far you take them. When elected
officials consult astrologers, I think there is some cause for concern!
Lots of money is spent on astrology! Peoples' lives are impacted!
- Question: why is astrology, and other pseudosciences/superstitions, so widespread?
- As the world becomes increasingly technologically
sophisticated, perhaps more people are looking for ``simplicity'',
and have difficulties assessing the validity of the different things they
are told.
- Perhaps it's driven by a few people, e.g., media. Or horoscope
writers!
- As populations grow, the number of rare events increases, and, if
these are well-publicized, this can give people an erroneous impression
of the frequency of such events. People are impressed by coincidences!
What is astronomy and what do astronomers do?
- Astronomy is the science of studying objects seen in the
sky. Astronomers try to understand the nature of astronomical objects,
figuring out what is out there, details about the physical nature of the
objects, and try to develop an understanding of why the objects look
what they look like, how they got there, and how they might change
with time.
- Jobs
- astronomy doesn't have too many immediate applications
which provide profit, so many astronomers are hired by the public
sector: universities and government research centers. However,
increasingly, astronomical missions are being built by the private
sector, so there's a growing number of astronomers hired by aerospace
industry.
- Skills learned in astronomy, e.g., scientific process and
critical thinking, are useful and in demand by many employers.
- Jobs in astronomy, science, engineering, technology are
numerous, pay fairly well, and often are interesting, have larger
schedule flexibility, and/or allow for some travelling.
- Research. Generally, there are three main types of research
activity that astronomers might do.
- observational research: collection and analyze data, namely light,
from astronomical objects.
- Collection of light usually requires staying up at night at a
telescope. However, in this day and age, the analysis of the data takes a
lot longer than the collection, so even purely observational astronomers
don't observe that many nights; typically, an astronomer might spend a few
to a dozen nights per year at the telescope. These days, most information
is recorded electronically, and observing at the telescope usually means
sitting in a warm room controlling the telescope and instrument with a
computer, looking at the data as it comes in to judge whether more data
is needed, listening to music, eating cookies, etc.
- Astronomers try to interpret what they are seeing in the light of
some model of what is going on in their objects, or try to come up with
some model of what is going on which other scientists can try to shoot
down! Computers usually play a large role in astronomical research
these days, as single pictures consist of LOTS of individual pieces
of information.
- theoretical research, where astronomers try to predict what objects
in the sky will look like based on the laws of physics. This may involve
lots of analytical work or computer modelling.
- Instrumentation, where tools are developed for use at the telescope.
- Many astronomers teach, and do public outreach
- There are some direct applications of astronomy: space mission support,
global positioning, etc., etc.
What is going on with astronomy at NMSU?
- We have an astronomy department which consists of 10 faculty
members plus some research faculty. We offer a graduate PhD program,
but we don't offer an undergraduate major, partly because we feel that
astronomers should have a firm basis, e.g. an undergraduate degree, in
physics, and partly because we wouldn't get enough majors. We have
about 25 graduate students.
- NMSU operates a large observatory at
Apache Point, about 2 hours
of Las Cruces.
There are several telescopes at this site. The largest is
3.5m diameter,
and is shared with University of Washington, Univ. of Chicago, Princeton,
Washington State, and Johns Hopkins; NMSU gets about 15% of the time.
We also have a 1m telescope. There is also a
2.5m telescope
that is doing an a survey of all objects in a big piece of the sky; NMSU is a
partner in this project.
- Apache Point is ``next door'' to the National Solar Observatory
in Sunspot NM. There is a joint visitor's center in Sunspot.
- In the department at NMSU, we do a wide variety of research: solar system,
stars, galaxies, observation and theory.
- Something I've been involved in: new camera
on the
Hubble Space Telescope
