Tag Archives: system

History of the Solar System by Minute Physics

I’ve only recently discovered Minute Physics, a production of Embry-Riddle Aeronautical University. They state, quite correctly in my mind, that if you can’t explain it in a minute, you don’t understand it. This echoes a statement by Bob Doms, of the University of Pennsylvania, who once said to our class, “You need to always be able to explain your work in one sentence so your mother can understand.”

This is close enough, from Minute Physics, ‘Why is the Solar System Flat?”:

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Posted by on January 10, 2014 in Uncategorized


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ImageLast week’s Science magazine had a pair of articles about Voyager 1’s arrival at the heliopause and the fluctuations of particles it has encountered. For about a year astronomers have been talking about the limits of the solar system.  An idea that I admit I had never entertained in any absolute way. Instead, my image of the extent of the solar system is mostly shaped by the most distant planets’ orbital paths. Sometime in the past decade or two, I became aware of plutoid objects, among which Pluto is one and that there is an Oort Cloud beyond that. I’ve always been a bit hazy about the details of what comprises the Oort cloud and how this differs from the plutoid objects.

Sometime during the conversation ignited by Pluto’s demotion to a dwarf planet, I head a good description of the solar system that described it as: four small, rocky planets close to the sun, then a belt of asteroids, followed by four large, gas planets, then another ring of small objects.


The edge of the solar system

I really am looking for someone to explain this in terms that a reasonably intelligent person without much astronomy background can comprehend. That is, I don’t want too much left out, but I’m not necessarily ready for an overly technical explanation.

With respect to local suns, what is the position of our solar system? What forces interact between the suns? What do we know of the space between solar systems (or between galaxies?)


A simplistic view of nine balls circling a star

That’s a pretty tidy description, but I think it leaves out a lot.

The interest now is in defining the edges, the limitation of the sun’s influence on space in favor of extra-solar forces. From what I gather, this is referring to both ‘solar wind’ and magnetic field.

I can understand this from the inside (although I need correcting here too) ,  but what I don’t fully grasp are what the forces are outside of the solar system. What dominates those forces? One thing I notice in the illustrations I’ve seen is a teardrop shape to the system resulting from a unidirectional current. What is this current? Is it emanating from other solar systems? Some local influence of nearby stars? Or a galactic force?


Heliosphere warping under external pressure

I hope someone out there can help me understand this better.

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Posted by on July 20, 2013 in Uncategorized


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Cancer and the immune system (briefly)

Macrophage engulfing bacteria

 What a breath of fresh air! A good old friend of mine, who I met while in graduate school and is now living in Mexico city has been working on a couple of papers that he is submitting to some English language journals. I’ve only read one of them so far – it’s an interesting review of work that suggests that tumors actively co-opt processes of the immune system to their own advantage. His spoken English is quite good, but it’s another thing altogether to write well for a scientific publication. Lucky for me, I guess, because it gives me a way to be involved.

It is well established that the immune system functions to prevent tumor formation known as immunosurveillance. This is pretty consistent with the basic role of defending the self against any non-self target it encounters. If you’re unfamiliar with immunology and want one thing to learn, that’s it: The immune system is there to recognize a black and white world of self vs non-self. The details are complicated, but it’s fairly well worked out that through a series of positive and negative selection events you can train your immune cells to be tolerant of you (self), but reactive against anything new (non-self).

With respect to cancer, it’s important to recognize that these cells start out as self and are ignored by the immune system, but they change in a way that they are not acting the way they should. The problem for the immune system is that these changes typically just mean that the cells are acting abnormally, but they don’t necessarily look foreign. Despite this, we know that animals that lack a functional immune system will succumb to tumors at higher frequency earlier in life than those with competent immunity.

My friend’s article extends this relationship beyond immunosurvellience and suggests that the tumor cells undergo a selection process by the immune system that will eliminate weaker cells, leaving only cells that either escape the notice of the immune system entirely or are extraordinarily resistant to attacks. Further, he describes that the remaining cells will often co-opt signals of the immune system to advance their own function and survival. 

I look forward to finishing up this paper and hope to be able to point you toward a journal that it is published in sometime in the near future. Until then, it’s so refreshing to think about immunology again. I miss it.


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Posted by on November 3, 2012 in Uncategorized


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