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..Is there a limit (known) to how small something can be.....
...the smallest known particle/life form in existence is

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[+3] - Ionus - 12/02/2009[quote]..Is there a limit (known) to how small something can be.....[/quote] The smallest known 'thing' would be a string in string THEORY. Outside of theory, the smallest known thing is a photon....

@galactus,

protons maybe? its been a while since i study anything like this.

1 Reply

@Seed,

Electrons are much much smaller then protons in terms of atomic weight and size.

Quote:

Particle physicists try to understand the nature of nature at the smallest scales possible. Today, we know that atoms do not represent the smallest unit of matter. Particles called quarks and leptons seem to be the fundamental building blocks - but perhaps there is something even smaller. Physicists are still far from understanding why a proton has about 2,000 times more mass than an electron. And on top of it all, scientists suspect a whole new class of undiscovered supersymmetric particles to complete the subatomic family.

http://www.fnal.gov/pub/inquiring/matter/index.html

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@galactus,

galactus wrote:

...the smallest known particle/life form in existence is

the brain cells of just about any politician

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@tsarstepan,

they both revolve around the same thing.... you say potato i say proton....

1 Reply

@Seed,

you say tomato, i say neutrino Confused

maybe not

1 Reply

@djjd62,

thats not even a meat....

0 Replies

@galactus,

Interesting question may when you consider that all "particles" can be thought of as aspects of "waves" with no boundaries.

0 Replies

@galactus,

Quote:

..Is there a limit (known) to how small something can be.....

The smallest known 'thing' would be a string in string THEORY. Outside of theory, the smallest known thing is a photon.

Quote:

the smallest known particle

Quarks are similar in size to electrons and are held together by gluons, but quarks are the smallest found from experiments. The photon is even smaller but some argue whether it has mass or not, the majority saying it must have mass. The problem is the massive amounts of energy required to produce evidence of these aprticles apart from mathematical modelling

Quote:

the smallest known life form in existence is

Are viruses alive ? If they are then they are the smallest life form, with ones like AIDS being some of the smallest. If viruses are not life, then some bacteria are the smallest.

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@Ionus,

Quote:

Alternative definitions:

S Luria et al. AJ Cann

And EP Rybicki, ©2008:

A virus is an infectious acellular entity composed of compatible genomic components derived from a pool of genetic elements.

The concept of a virus as an organism challenges the way we define life:

viruses do not respire,
nor do they display irritability;
they do not move
and nor do they grow,
however, they do most certainly reproduce, and may adapt to new hosts.
By older, more zoologically and botanically biased criteria, then, viruses are not living. However, this sort of argument results from a "top down" sort of definition, which has been modified over years to take account of smaller and smaller things (with fewer and fewer legs, or leaves), until it has met the ultimate "molechisms" or "organules" - that is to say, viruses - and has proved inadequate.

If one defines life from the bottom up - that is, from the simplest forms capable of displaying the most essential attributes of a living thing - one very quickly realises that the only real criterion for life is:

The ability to replicate.

http://www.mcb.uct.ac.za/tutorial/virwhat.html#Viruses

1 Reply

@contrex,

It certainly seems that way, a planck length is probably the last thing in this universe in that direction.

In my post previously, perhaps I should have added that particle physics is reaching the end of its usefulness, as it has determined the existence of Quarks, which are considered to be strings. Possibly the smallest string would have the length of a planck, but they grow when they interact with other strings. Finding a string this small (1 Planck) with current theory would require almost unimaginable amounts of energy, but we have got as far down as Quarks, and have mathematical models of the energy binding Quarks together called Colour Force. This is so named to distinguish it from all other forces as it is quite different and seperate. In particle physics this colour force is mediated by a "particle" called a gluon. In string theory, there probably will not be such a particle as a gluon, it will be the interaction or even the joining together of strings directly to form a Quark.

Size and frequency are the main criteria that determine which string is actually a particle.

1 Reply

@Ionus,

THe smallest living organism is probably the nanobacter sp. Its about 50 nanometeers ( sizes are usually defined by microparticulate sieving where we take stuff down to 10 nanometers, where the sieves are actually defect crystal lattices with statistically accurate values). In 2007 it was finally determined that nanobacter were living , based upon their ability to accept uracil and convert it to uradine (a function of simple life metabolism).
Ive always been taught that the original smallest living thing was the Mycoplasma genitalium. That was until the nanobacter were found in the mars clinker and in several fossil deposits where , due to extremely calm waters, fine bacterial debris layers were formed over time, in almost tree ring like laminae. Inside these weve fpund the nanobacter and when some dude found living examples in boiling springs in NM and in Iceland, they went to work raising the little dears.

Seems they do everything wed ask living things to do, yet there still is some debate about whether they are ALIVE or are just efficient chemical "paleo-pre--protists, like viruses.

1 Reply

@farmerman,

An enjoyable read. Good one farmerman.

0 Replies

@tsarstepan,

The reason I said there was doubt for viruses is because some believe they are DNA fragments, others believe they were before DNA. Whichever, they require other organisms to survive and might be thought of as not independent life, though that doesnt mean they were always like this, they might have evolved this way.

0 Replies

Where do prions fit in all this?

2 Replies

@ossobuco,

Quote:

Prions, the agents of BSE or "mad cow disease", are even smaller than viruses and seem yet stranger. Neither viruses or prions, it seems, can exist without living organisms, but they do not themselves fulfill the common definitions for life.

http://earthguide.ucsd.edu/virtualmuseum/litu/01_2.shtml

1 Reply

@tsarstepan,

yes, but where does a Prius fit into all this?

1 Reply

@djjd62,

We can only answer that question once the engineering department develops a nano sized convertible of the Toyota branded hybrid car.

0 Replies

@ossobuco,

You like hard questions dont you ? Very Happy

There are four basic elements in living chenistry : carbon, hydrogen, oxygen and nitrogen.

These combine in various ways to form amino acids. Amino acids are used by life to perform fuctions just as they are, and also to build bigger and better life sustaining structures... proteins, for example.

Proteins are amino acids glued into one long chain - sideways thou shall not grow - but they have a secondary structure which is the way they curl and twist. Many proteins once they have assumed their secondary structure stay that way. If you are bitten by a snake, it will be a protein that causes the damage. Proteins account for the biggest single amount of compounds in your body after water is removed, probably about half of your dry weight.

Special proteins that can change shape (usually only once) are called prions. Prions are believed to cause some diseases, Mad Cow disease being one that comes to mind. Where the amino acids join, prions invade and use the mechanism to manufacture themselves.

By adding phosphorus to our four biggies mentioned above at the amino acids level, we can make nucleic acids which are very large molecules in a chain like structure. Two variants of nucleic acids are DNA and RNA. DNA is essential for cellular life, whereas RNA is the structure for viruses. Both DNA and RNA use amino acids in their housekeeping. This is where prions have an effect on life. And that is the connection.

1 Reply

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