Negative Definition and 1000 Threads

In mathematics, a negative number represents an opposite. In the real number system, a negative number is a number that is less than zero. Negative numbers are often used to represent the magnitude of a loss or deficiency. A debt that is owed may be thought of as a negative asset, a decrease in some quantity may be thought of as a negative increase. If a quantity, such as the charge on an electron, may have either of two opposite senses, then one may choose to distinguish between those senses—perhaps arbitrarily—as positive and negative. Negative numbers are used to describe values on a scale that goes below zero, such as the Celsius and Fahrenheit scales for temperature. The laws of arithmetic for negative numbers ensure that the common-sense idea of an opposite is reflected in arithmetic. For example, −(−3) = 3 because the opposite of an opposite is the original value.
Negative numbers are usually written with a minus sign in front. For example, −3 represents a negative quantity with a magnitude of three, and is pronounced "minus three" or "negative three". To help tell the difference between a subtraction operation and a negative number, occasionally the negative sign is placed slightly higher than the minus sign (as a superscript). Conversely, a number that is greater than zero is called positive; zero is usually (but not always) thought of as neither positive nor negative. The positivity of a number may be emphasized by placing a plus sign before it, e.g. +3. In general, the negativity or positivity of a number is referred to as its sign.
Every real number other than zero is either positive or negative. The non-negative whole numbers are referred to as natural numbers (i.e., 0, 1, 2, 3...), while the positive and negative whole numbers (together with zero) are referred to as integers. (Some definitions of the natural numbers exclude zero.)
In bookkeeping, amounts owed are often represented by red numbers, or a number in parentheses, as an alternative notation to represent negative numbers.
Negative numbers appeared for the first time in history in the Nine Chapters on the Mathematical Art, which in its present form dates from the period of the Chinese Han Dynasty (202 BC – AD 220), but may well contain much older material. Liu Hui (c. 3rd century) established rules for adding and subtracting negative numbers. By the 7th century, Indian mathematicians such as Brahmagupta were describing the use of negative numbers. Islamic mathematicians further developed the rules of subtracting and multiplying negative numbers and solved problems with negative coefficients. Prior to the concept of negative numbers, mathematicians such as Diophantus considered negative solutions to problems "false" and equations requiring negative solutions were described as absurd. Western mathematicians like Leibniz (1646–1716) held that negative numbers were invalid, but still used them in calculations.

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  1. E

    How does Heat Death work in a universe with negative curvature?

    I'm assuming that the observer witnesses all other particles enter a horizon, be it an event horizon or the particle horizon. Thus the observer's observable universe would contain himself only. Is this understanding correct and can it happen in finite time? Also does such a universe have time...
  2. J

    Reflection in a mirror of negative curvature

    How Does Reflection Behave In Arbitrary Surfaces Hi I am interested to know how reflection would behave in a mirror on a surface of negative [gaussian] curvature. I tried googleing it and found nothing useful Thanks Edit: Reflection in a sphere behaves like inversion in a sphere...
  3. M

    Identify which of the ff. object will be positive or negative charge

    Identify which of the ff. object will be positive or negative charge 1) Hand and Hair 2) PVC and Tetlon 3) Glass and Poly ester 4) Rubber and rubber 5) Hand and wood
  4. S

    What is positive and negative eigenspaces? Can you recommend me a

    What is positive and negative eigenspaces? Can you recommend me a referance to know them?
  5. V

    Exploring Negative Time and its Effects

    Hello All I'm new to the forum and have a question. I was looking at the time dilation function and noticed that negative time would be described with imaginary numbers and be a kind of anti-time, albeit that rest mass can not be pushed faster than the speed of light but for the sake of...
  6. DevilsAvocado

    News S&P Downgrades US To AA+, Outlook Negative

    https://www.youtube.com/watch?v=jERhPMzqSaE http://www.cnbc.com/id/44039103" "More broadly, the downgrade reflects our view that the effectiveness, stability, and predictability of American policymaking and political institutions have weakened at a time of ongoing fiscal and economic...
  7. N

    Exploring Negative Energy: What Makes It So?

    can a matter have negative energy? or more appropriately what makes some energy as negative?
  8. R

    Electric field of a loop with one positive halve and one negative halve

    Homework Statement Given a circular wire with radius R. Choose the origin in the center of the circle, the z-axis perpendicular to the circle. One halve of the circle contains a positive line charge \lambda, the other halve a negative line charge of the same magnitude. (a) Sketch the electric...
  9. R

    Positive and Negative 5v from 2 AA Batteries

    I'm designing a portable device running off of 2 AA batteries that requires positive both positive and negative 5v power at the same time. What is the best/cheapest way to achieve this?
  10. M

    What if a black hole had a negative size ?

    If maths tells us 1 * -1 = -1 and it takes a positive cell to repel a positive cell ... could in theory a negative black hole never be reversed ?
  11. C

    Should work done be written as negative value?

    For example: i) Someone lifts 2kg flowerpot 1m vertically upward. The work done by the gravity is -19.62 J? Then, if ii) A 3kg box on the floor is lifted vertically up onto the head and then lowered down to the shoulder. The shoulder is 150cm while the top of the head is 175cm measured...
  12. S

    Negative voltage on emitter follower

    Hi, Iam reading horowitz and hill and came through this paragraph in section 2.03 Emitter follower : Notice (Section 2.01, rule 4) that in an emitter follower the npn transistor can only "source" current. For instance, in the loaded circuit shown in Figure 2.8 the output can swing to...
  13. jfy4

    Is a (-,-,-,-) metric signature meaningful?

    Hi, Is a metric signature of (-,-,-,-) unphysical? Thanks,
  14. N

    Finding EMF - why we ignore the negative sign in Faraday's law

    Hi all, I've been using Faraday's law to find the EMF in a coil of wire in a changing magnetic field. EMF = -N (change in mag flux/change in time) for N loops I'm finding that the EMF is always positive regardless of whether the change in flux is positive or negative. I'm wondering at...
  15. Z

    What is a negative magnetic moment?

    Protons have a magnetic moment of 2.8 μN, Neutrons have a magnetic moment of −1.9 μN. What is the meaning of the negative sign? Does the Neutron go a different direction in a magnetic field? How do they know it isn't just upside down? Is there any kind of a visual picture of a magnet that...
  16. H

    Why is the Time component in the Space Time Interval negative?

    Why is the Time component in the Space Time Interval negative? The space time interval is defined to be: ds^2=dt^2-dx^2-dy^2-dz^2 or depending on the convention used it may also be: ds^2=-dt+dx^2+dy^2+dz^2 The equation is defining distance using the pythagorean theorem. This results...
  17. F

    Electrostatics: can a positive charge induce negative potential?

    Can a charge, brought into a chargeless world filled with some geometry of conductors and dielectrics, induce a negative potential anywhere in that world? I feel the answer is no. But I cannot think of a good way to prove it, or even attack the problem. More explicitly, imagine a world...
  18. A

    Why can a velocity of a wave be negative?

    Hi yall, Im trying to understand waves and I am wondering why the velocities are negative sometimes and or positive. I think that the velocities are negative because of the slope of the wave as it is coming down? I just want to completely understand it and am a little confused. Like...
  19. N

    Negative Resistance in Resonant Tunneling

    Hi, I am a student who's learning about quantum mechanics. I was reading about the RTD (Resonant tunneling diode) and I got the general idea. However, I was looking at a I vs V graph and came up with a question. Since Resistance = V/I, the inverse slope of the I vs V graph has to be the...
  20. S

    Positive & Negative charge of Tungsten

    Homework Statement How much positive and negative charge are in a 50g Tungsten ring? Homework Equations Standard atomic weight 183.84 The Attempt at a Solution
  21. AJKing

    [Intro Chemisty] Positive and negative charges.

    I'm just learning but I can almost SWEAR that this is right, just reassure me?
  22. T

    Β+ decay: voiding conservation of mass or creating something with negative mass

    From Wikipedia: "Positron emission or beta plus decay (β+ decay) is a type of beta decay in which a proton is converted, via the weak force, to a neutron, releasing a positron (the antimatter counterpart of an electron) and a neutrino. Isotopes which undergo this decay and thereby emit...
  23. H

    Negative sign in hopping amplitude

    Might be a naive question. In many places, specially in the Hubbard model, people use a minus sign before the tight-binding hopping amplitude. What does the negative sign signify for? Any special intention? Thanks.
  24. A

    Negative maximum kinetic energy in Millikan's data?

    What am I finding to be confusing.. The graphs of Millikan's data were straight lines with equal slopes. The graph was plotted maimum kinetic energy (eV) versus the frequency of the wave. This was the graph that produced the linear relationship from the photoelectric effect. What does it mean...
  25. N

    Understanding Negative Quantum States: A Simplified Explanation by Dirac

    can somebody simply explain what is meant by NEGATIVE QUANTUM STATES , as given by dirac in his theory?i know its not as SIMPLE as i want it to be , but still I would like to know its significance in the most basic way!
  26. E

    What Causes Negative Work in Physics?

    Hello everyone. I understand the concept of work in general, but the concept of negative work still somewhat baffles me. One of my main problems is this: according to my textbook, 3 conditions must be met in order for work to be done, and one of them is "at least part of the force must be in...
  27. N

    May I suggest an experiment concerning negative energy?

    Sometimes to understand things I need to come up with ideas and have them shot down. This is what I am doing here. I have been informed that the Cashmeir effect may not be due to negative energy so I have an idea for an additional experiment. Suppose we were to make a "box" with little...
  28. J

    When Should 'g' Be Negative in Physics Equations?

    Hi PF, just a quick question that always seems to confuse me.. when should 'g' be negative in equations? Intuitively, I tend to always substitute -9.81 m/s into equations but it seems that this can be incorrect in special cases. Are there certain situations where 'g' should be or shouldn't be...
  29. A

    What is mass? and is negative matter really possible

    what is mass? and is negative matter really possible i wasnt sure if i should post it in this forum or not but i thought the second part of the title refers to particle physics so i posted this here. so as the title suggests i was wondering what is mass. i have heard answeres like it is a...
  30. B

    Proving Negative G-Forces with an Example

    Hi, nice forum. I was thinking how I would go about proving with an example, that negative Gs are occurring? Homework Statement Say a stunt pilot is doing a maneuver that will expose him to negative Gs. It could look like this...
  31. Femme_physics

    Circuit can supply negative voltages ?

    Circuit can supply "negative voltages"? I read an article trying to understand voltage dividers better. I then read this quote that threw me off! Now, what does it mean that a circuit is designed to supply both positive and negative voltages? I'm pretty new to electricity. All I need is...
  32. N

    How much negative energy is that space between two non-conducting plates?

    The negative pressure generated in the Cashmeir effect suggest that negative energy can exist in small spaces between non-conducting plates. How much negative energy exist in a given amount of space as measured in units that refer to energy (as opposed to units of force created by the Cashmeir...
  33. R

    Potential Energy of a Liquid - Why is it Negative for Small Molar Volumes?

    I was just reading a book on low-temperature physics and stumbled upon a graph that shows the energy of liquid Helium-4 in relation to its molar volume. The graph includes both zero-point energy and the potential energy of the liquid, and the latter goes steeply (basically a vertical line) from...
  34. O

    How to divide positive and negative charges from each other

    How to divide positive and negative charges from each other without them interacting with other matter or charge patterns. ,please answer I only need this to make my ultimate machine
  35. B

    Solving algebraic equations with negative exponents

    solve for x: x^-2 = 1/9 solve for x: x^-2 - 13x^-1 +36 = 0 I don't understand how to solve either equations.
  36. B

    Getting Rid of Negative Exponent

    Getting Rid of Negative Exponent! Homework Statement So I am solving a Diff Eq ( separable equation) and I am down the the last step. After integrating both sives and solving for y I am left with y^(-2) on the left hand side. How do I finalize it and get rid of negative 2 expononent...
  37. D

    Negative pressure & Hydrostatic paradox

    2 parts: 1. What does it mean if you get a negative gauge pressure value when calculating from manometer containing compound liquid? When calculating absolute pressure how does atmospheric pressure affect this negative pressure ie. atmospheric pressure opposes the direction of force? 2...
  38. H

    Can Negative Speed of Light Allow Time Travel?

    i am only a year 11 student so i don't know much about the Theory of relativity i just heard that if we can travel at the speed of light our time will be slower than the other so i am just wondering if we can travel at a negative speed of light that means that we can go back in time?
  39. P

    How can negative potential difference be achieved in an electric circuit?

    I've heard about this over and over again, but i don't how this(negative pd) can be achieved in an electric circuit.
  40. J

    Negative binomail distribution and its variance

    Hi, I am trying to estimate variance for negative Binomial distribution using maximum likelihood estimation and Expected (Fisher's) information to determine its variance. I know what variance is for this distrubution but I cannot derive it. Here is my solution. Any comments and...
  41. S

    Integral of 1/(1-x) is -ln(abs(1-x)). why negative?

    Why is int(1/(1-x))=-ln(abs(1-x))? If you substitute u=1-x then int(u)=ln(abs(u))=ln(abs(1-x)) Also, in this question you're trying to find the particular solution y=f(x) to the given differential euqation with initial conditions f(-1)=2 dy/dx=6x^2-x^2y d^2y/dx^2=-12. So i get to...
  42. B

    Exploring the Hypothetical Possibilities of Negative Mass

    Let's say that negative mass existed, what might it look like? Could it look like an ordinary rock stuck in the ground? If so, what would happen if you tried to move it around? If it moves in the opposite direction it is push then wouldn't it be impossible to move it in any direction? Would it...
  43. N

    Statistics: Probability of False Negative during Measurement

    Hello Everyone, My statistics is terribly rusty so I am turning to all of you for assistance! I am in the process of reviewing my old text but I figured this may be quite a bit quicker. Homework Statement Suppose "x" is normally distributed with "mu_1" and "sigma_1." Now suppose x is measured...
  44. S

    Gamma Function on negative Fractions

    Gamma Function on negative Fractions! If we take a look at the Gamma Function and evaluate the integral by parts then we will get infinity in the first step of Integration by Parts eg: Integral e^-1*x^-5/3 Limits being 0 to Infinity as usual! If we try to integrate this we will get...
  45. G

    The Klein Paradox - Exploring Beyond the Negative Coefficient of Transmission

    The Klein Paradox is the name given to the following prediction of Klein Gordon's equations. If you send a current of electrons against a potential barrier of height V such that the energy of the incident electrons is less then V - m, you should observe a current of positrons coming out of the...
  46. S

    Why Is dz/dt Negative in Cosmology?

    Homework Statement I am working with cosmology and expansion. Obtain dz/dt as a function of z and H_o only. What is the sign for dz/dt and why? z is the redshift and H_o is the Hubble constant. Homework Equations The Attempt at a Solution So I found the equation for dz/dt =...
  47. T

    Proving the Positivity of Negative Times Negative: An Algebraic Approach

    What's the proof for a negative number times another negative number gives a positive number? Thank you
  48. C

    Understanding Virtual Objects and Negative Do Values in Lenses

    I would appreciate some clarification on working with lenses and virtual objects (when the object distance do is negative). I'm not sure what happens when the do is negative and you get a positive value for di. On which side of the lens does the image go? Normally, for a lens, if di is...
  49. A

    Relative humidity at negative temperature

    as we know at zero degree temp. water condense to form ice. so what will be the relative humidity of a chamber at a temperature below zero degree temp.? will it be nagative or what?
  50. S

    Restrictions of denominators with negative exponents.

    what are the restrictions (if any) on y=1/x^(-2)? is it equal to just x^2 so no restrictions or what it is have hole at x=0? or do you change too all positive exponents before looking at restrictions? what exactly are the exponents rules that govern this stuff so confused
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