diff --git a/interactions.py b/interactions.py
index f2dd313..8328444 100644
--- a/interactions.py
+++ b/interactions.py
@@ -100,13 +100,18 @@ ema_weight = 2/(frame_rate+1)
 
 inductance = 0.001
 
-therm_conduct = 0.001
+therm_conduct = 0.01
 
 drain = False
 drain_rate = 0.1
 
 # === phase space ===
 
+# heat equation
+temp = 30*[0]
+new_temp = 30*[0]
+
+# wave equation
 charge = 12*[0]
 current = 30*[0]
 
@@ -117,11 +122,13 @@ change_threshold = 0.15
 
 def heat_evolution():
   for e, f in cyc_edge_adj:
-    flow = therm_conduct*(current[e] - current[f])
-    current[e] -= flow
-    current[f] += flow
+    flow = therm_conduct*(temp[e] - temp[f])
+    new_temp[e] -= flow
+    new_temp[f] += flow
+  for e in range(30):
     if drain:
-      current[v] *= 1 - drain_rate
+      new_temp[e] *= 1 - drain_rate
+    temp[e] = max(new_temp[e], 0)
 
 def wave_evolution():
   # use verlet integration, first updating the currents and then using the new
@@ -137,6 +144,15 @@ def wave_evolution():
     for v in range(12):
       charge[v] *= 1 - drain_rate
 
+def set_heat_light(e, i):
+  new_litness = 1 - exp(-2*i)
+  if abs(new_litness - litness[e]) > change_threshold:
+    hit_bridge = True
+    litness[e] = new_litness
+  else:
+    hit_bridge = False
+  set_light_hsv(e, (0.167*litness[e], 1 - 0.5*litness[e]*litness[e], litness[e]), hit_bridge)
+
 def set_wave_light(e, i):
   new_litness = 1 - exp(-2*i*i)
   if abs(new_litness - litness[e]) > change_threshold:
@@ -146,6 +162,38 @@ def set_wave_light(e, i):
     hit_bridge = False
   set_light_hsv(e, (0.45 + litness[e]*0.25, 1 - 0.5*litness[e]*litness[e], litness[e]), hit_bridge)
 
+def handle_heat_events():
+  global drain
+  for event in pygame.event.get():
+    if event.type == pygame.KEYDOWN:
+      if event.key == pygame.K_j:
+        new_temp[0] += 10
+      elif event.key == pygame.K_SPACE:
+        drain = True
+    elif event.type == pygame.KEYUP:
+      if event.key == pygame.K_SPACE:
+        drain = False
+    elif event.type == pygame.QUIT:
+      quit()
+
+def handle_wave_events():
+  global drain
+  for event in pygame.event.get():
+    if event.type == pygame.KEYDOWN:
+      if event.key == pygame.K_j:
+        charge[0] += 100
+        charge[11] -= 100
+      elif event.key == pygame.K_k:
+        charge[5] += 100
+        charge[7] -= 100
+      elif event.key == pygame.K_SPACE:
+        drain = True
+    elif event.type == pygame.KEYUP:
+      if event.key == pygame.K_SPACE:
+        drain = False
+    elif event.type == pygame.QUIT:
+      quit()
+
 def show_data(screen):
   # light updates
   global updates, new_updates
@@ -157,23 +205,27 @@ def show_data(screen):
   screen.blit(text, (120, viewsize))
   
   # energy
-  energy = 0.5*(sum(q*q for q in charge) + inductance*sum(i*i for i in current))
+  ##energy = 0.5*(sum(q*q for q in charge) + inductance*sum(i*i for i in current))
+  energy = sum(temp)
   text = font.render('energy', True, (255, 255, 255))
   screen.blit(text, (20, 30 + viewsize))
   text = font.render(str(energy), True, (255, 255, 255))
   screen.blit(text, (120, 30 + viewsize))
   
   # charge[0]
-  text = font.render('charge[0]', True, (255, 255, 255))
+  ##text = font.render('charge[0]', True, (255, 255, 255))
+  text = font.render('temp[0]', True, (255, 255, 255))
   screen.blit(text, (20, 60 + viewsize))
-  text = font.render(str(charge[0]), True, (255, 255, 255))
+  ##text = font.render(str(charge[0]), True, (255, 255, 255))
+  text = font.render(str(temp[0]), True, (255, 255, 255))
   screen.blit(text, (120, 60 + viewsize))
 
 if __name__ == '__main__':
   # set up background
   background = pygame.Surface(screen.get_size()).convert()
   background.fill((32, 32, 32))
-  text = font.render('press [j] or [k] to pluck', True, (255, 255, 255))
+  ##text = font.render('press [j] or [k] to pluck', True, (255, 255, 255))
+  text = font.render('press [j] to pluck', True, (255, 255, 255))
   background.blit(text, (340, viewsize))
   text = font.render('hold [space] to drain', True, (255, 255, 255))
   background.blit(text, (340, 30 + viewsize))
@@ -181,22 +233,8 @@ if __name__ == '__main__':
   to_light = 0
   while True:
     # handle events
-    for event in pygame.event.get():
-      if event.type == pygame.KEYDOWN:
-        if event.key == pygame.K_j:
-          charge[0] += 100
-          charge[11] -= 100
-        elif event.key == pygame.K_k:
-          charge[5] += 100
-          charge[7] -= 100
-        elif event.key == pygame.K_SPACE:
-          drain = True
-        pygame.draw.aaline(screen, (255, 255, 255), (0, 0), (viewsize, viewsize))
-      elif event.type == pygame.KEYUP:
-        if event.key == pygame.K_SPACE:
-          drain = False
-      elif event.type == pygame.QUIT:
-        quit()
+    ##handle_wave_events()
+    handle_heat_events()
     
     # clear screen
     screen.blit(background, (0, 0))
@@ -206,11 +244,12 @@ if __name__ == '__main__':
     
     # show state
     for e in range(30):
-      set_wave_light(e, current[e])
+      ##set_wave_light(e, current[e])
+      set_heat_light(e, temp[e])
     
     # evolve state
-    wave_evolution()
-    ##heat_evolution()
+    ##wave_evolution()
+    heat_evolution()
     
     # step
     pygame.display.flip()